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Can one bit of light bounce off another bit of light? | Yes, one bit of light can bounce off another bit of light, but not directly, and the effect is very rare. Light is made out of small quantum objects called photons. When you turn on a lamp, the light bulb begins creating and emitting trillions upon trillions of photons. Photons are in a class of quantum particles know... | tag/antimatter/ | context: tag/antimatter/ question: Can one bit of light bounce off another bit of light? | Yes, one bit of light can bounce off another bit of light, but not directly, and the effect is very rare. Light is made out of small quantum objects called photons. When you turn on a lamp, the light bulb begins creating and emitting trillions upon trillions of photons. Photons are in a class of quantum particles know... |
Does the negative mass of antimatter mean that it's gravitationally repelled from stars? | Antimatter does not have negative mass. In our universe, there is no such thing as negative mass. Mass only comes in positive form. In contrast, electric charge can be positive or negative. The nonexistence of negative mass has profound consequences. First, gravity is always attractive and never repulsive. Presumably,... | tag/antimatter/ | context: tag/antimatter/ question: Does the negative mass of antimatter mean that it's gravitationally repelled from stars? | Antimatter does not have negative mass. In our universe, there is no such thing as negative mass. Mass only comes in positive form. In contrast, electric charge can be positive or negative. The nonexistence of negative mass has profound consequences. First, gravity is always attractive and never repulsive. Presumably,... |
How can you tell a black hole made out of antimatter from a black hole made out of matter? | According to our current understanding, there is no way to distinguish an antimatter black hole from a regular-matter black hole. In fact, there is no difference between an antimatter black hole and a regular-matter black hole if they have the same mass, charge, and angular-momentum. First of all, antimatter is just l... | tag/antimatter/ | context: tag/antimatter/ question: How can you tell a black hole made out of antimatter from a black hole made out of matter? | According to our current understanding, there is no way to distinguish an antimatter black hole from a regular-matter black hole. In fact, there is no difference between an antimatter black hole and a regular-matter black hole if they have the same mass, charge, and angular-momentum. First of all, antimatter is just l... |
Is there any difference between antimatter, dark matter, dark energy, and degenerate matter? | Yes. Although the names sound vague and almost fictional, the types of matter called antimatter, dark matter, dark energy, and degenerate matter are all different, specific entities that really exist in our universe. Antimatter is just regular matter with a few properties flipped, such as the electric charge. For exam... | tag/antimatter/ | context: tag/antimatter/ question: Is there any difference between antimatter, dark matter, dark energy, and degenerate matter? | Yes. Although the names sound vague and almost fictional, the types of matter called antimatter, dark matter, dark energy, and degenerate matter are all different, specific entities that really exist in our universe. Antimatter is just regular matter with a few properties flipped, such as the electric charge. For exam... |
Are there nuclear reactions going on in our bodies? | Yes, there are nuclear reactions constantly occurring in our bodies, but there are very few of them compared to the chemical reactions, and they do not affect our bodies much. All physical objects are made of molecules. A molecule is a series of atoms linked together by chemical (electromagnetic) bonds. Inside each at... | tag/atom/ | context: tag/atom/ question: Are there nuclear reactions going on in our bodies? | Yes, there are nuclear reactions constantly occurring in our bodies, but there are very few of them compared to the chemical reactions, and they do not affect our bodies much. All physical objects are made of molecules. A molecule is a series of atoms linked together by chemical (electromagnetic) bonds. Inside each at... |
Are two atoms of the same element identical? | No. Two atoms of the same chemical element are typically not identical. First of all, there is a range of possible states that the electrons of an atom can occupy. Two atoms of the same element can be different if their electrons are in different states. If one copper atom has an electron in an excited state and anoth... | tag/atom/ | context: tag/atom/ question: Are two atoms of the same element identical? | No. Two atoms of the same chemical element are typically not identical. First of all, there is a range of possible states that the electrons of an atom can occupy. Two atoms of the same element can be different if their electrons are in different states. If one copper atom has an electron in an excited state and anoth... |
Can sound waves generate heat? | Yes, sound waves can generate heat. In fact, sound waves almost always generate a little bit of heat as they travel and almost always end up as heat when they are absorbed. Sound and heat are both macroscopic descriptions of the movement of atoms and molecules. Sound is the ordered movement of atoms and molecules in r... | tag/atom/ | context: tag/atom/ question: Can sound waves generate heat? | Yes, sound waves can generate heat. In fact, sound waves almost always generate a little bit of heat as they travel and almost always end up as heat when they are absorbed. Sound and heat are both macroscopic descriptions of the movement of atoms and molecules. Sound is the ordered movement of atoms and molecules in r... |
Can the decay half-life of a radioactive material be changed? | Yes, the decay half-life of a radioactive material can be changed. Radioactive decay happens when an unstable atomic nucleus spontaneously changes to a lower-energy state and spits out a bit of radiation. This process changes the atom to a different element or a different isotope. Since radioactive decay is a spontane... | tag/atom/ | context: tag/atom/ question: Can the decay half-life of a radioactive material be changed? | Yes, the decay half-life of a radioactive material can be changed. Radioactive decay happens when an unstable atomic nucleus spontaneously changes to a lower-energy state and spits out a bit of radiation. This process changes the atom to a different element or a different isotope. Since radioactive decay is a spontane... |
Do atoms ever actually touch each other? | The answer depends on what you mean by "touch". There are three possible meanings of touch at the atomic level: 1) two objects influence each other, 2) two objects influence each other significantly, or 3) two objects reside in the exact same location. Note that the everday concept of touch (i.e the hard boundaries of... | tag/atom/ | context: tag/atom/ question: Do atoms ever actually touch each other? | The answer depends on what you mean by "touch". There are three possible meanings of touch at the atomic level: 1) two objects influence each other, 2) two objects influence each other significantly, or 3) two objects reside in the exact same location. Note that the everday concept of touch (i.e the hard boundaries of... |
Does an atom have a color? | The answer really depends on how you define "having a color". The term "color" refers to visible light with a certain frequency, or a mixture of visible light frequencies. Therefore, the word "color" describes the frequency content of any type of visible light. Anytime visible light is present, we can describe it as h... | tag/atom/ | context: tag/atom/ question: Does an atom have a color? | The answer really depends on how you define "having a color". The term "color" refers to visible light with a certain frequency, or a mixture of visible light frequencies. Therefore, the word "color" describes the frequency content of any type of visible light. Anytime visible light is present, we can describe it as h... |
Does an electron in an atom move at all? | First of all, I assume you meant to ask the question, "Does an electron in a stable (non-transitioning) atomic state experience any movement?" Obviously, an electron that is transitioning between states is moving from one state to the other. But for an electron that is just staying in one stable state in an atom, the ... | tag/atom/ | context: tag/atom/ question: Does an electron in an atom move at all? | First of all, I assume you meant to ask the question, "Does an electron in a stable (non-transitioning) atomic state experience any movement?" Obviously, an electron that is transitioning between states is moving from one state to the other. But for an electron that is just staying in one stable state in an atom, the ... |
Does the human body contain minerals? | For the most part, the human body does not contain minerals. Scientifically speaking, a mineral is a naturally-occurring inorganic crystalline solid with a single chemical formula. Rocks are aggregates of minerals and organic materials. Except for in bones and teeth, the atoms and molecules making up a healthy body ar... | tag/atom/ | context: tag/atom/ question: Does the human body contain minerals? | For the most part, the human body does not contain minerals. Scientifically speaking, a mineral is a naturally-occurring inorganic crystalline solid with a single chemical formula. Rocks are aggregates of minerals and organic materials. Except for in bones and teeth, the atoms and molecules making up a healthy body ar... |
How can an electron leap between atomic levels without passing through all the space in between? | An electron that is transitioning between two atomic states does not skip any intervening space. The idea of a quantum leap is highly misleading and commonly misunderstood. First of all, an electron is a quantum object. As such, it acts both as a wave and as a particle at the same time. When bound as part of an atom, ... | tag/atom/ | context: tag/atom/ question: How can an electron leap between atomic levels without passing through all the space in between? | An electron that is transitioning between two atomic states does not skip any intervening space. The idea of a quantum leap is highly misleading and commonly misunderstood. First of all, an electron is a quantum object. As such, it acts both as a wave and as a particle at the same time. When bound as part of an atom, ... |
How can radioactive decay just happen with nothing triggering it? | Although a radioactive decay event seems spontaneous and is unpredictable, it is indeed triggered by a physical agent. That physical agent is a vacuum fluctuation. Due to the quantum nature of the universe, a vacuum always contains vacuum fluctuations. Vacuum fluctuations are also called vacuum energy and zero-point e... | tag/atom/ | context: tag/atom/ question: How can radioactive decay just happen with nothing triggering it? | Although a radioactive decay event seems spontaneous and is unpredictable, it is indeed triggered by a physical agent. That physical agent is a vacuum fluctuation. Due to the quantum nature of the universe, a vacuum always contains vacuum fluctuations. Vacuum fluctuations are also called vacuum energy and zero-point e... |
How does dissolving a salt molecule in water make its atoms ionize? | Dissolving a salt molecule in water does not make its atoms ionize. The atoms in solid salts are already ionized long before touching water. Electrons in an atom can only take on specific wave states, and only one electron can occupy one wave state at a time. As a result, electrons in an atom take different states, st... | tag/atom/ | context: tag/atom/ question: How does dissolving a salt molecule in water make its atoms ionize? | Dissolving a salt molecule in water does not make its atoms ionize. The atoms in solid salts are already ionized long before touching water. Electrons in an atom can only take on specific wave states, and only one electron can occupy one wave state at a time. As a result, electrons in an atom take different states, st... |
If I hammered and flattened a penny enough, could I cover the entire earth with it? | No. If you spread out the atoms from a single penny over the entire surface of the earth, you would no longer have a single piece of solid material since the atoms would be too far apart to bond to each other. Let's do some careful calculations to show this result. A modern United States penny has a mass of 2.500 gram... | tag/atom/ | context: tag/atom/ question: If I hammered and flattened a penny enough, could I cover the entire earth with it? | No. If you spread out the atoms from a single penny over the entire surface of the earth, you would no longer have a single piece of solid material since the atoms would be too far apart to bond to each other. Let's do some careful calculations to show this result. A modern United States penny has a mass of 2.500 gram... |
What is the shape of an electron? | Depending on how you define "shape", an electron either has no shape, or an electron can take on various wave shapes. The shape of an electron is never statically round like an orange. The reason for this is that an electron is not a solid little ball, despite being so often portrayed this way in the popular media and... | tag/atom/ | context: tag/atom/ question: What is the shape of an electron? | Depending on how you define "shape", an electron either has no shape, or an electron can take on various wave shapes. The shape of an electron is never statically round like an orange. The reason for this is that an electron is not a solid little ball, despite being so often portrayed this way in the popular media and... |
What is the strongest magnetic field possible? Is there a limit? | There is no firmly-established fundamental limit on magnetic field strength, although exotic things start to happen at very high magnetic field strengths. A magnetic field exerts a sideways force on a moving electric charge, causing it to turn sideways. As long as the magnetic field is on, this turning continues, caus... | tag/atom/ | context: tag/atom/ question: What is the strongest magnetic field possible? Is there a limit? | There is no firmly-established fundamental limit on magnetic field strength, although exotic things start to happen at very high magnetic field strengths. A magnetic field exerts a sideways force on a moving electric charge, causing it to turn sideways. As long as the magnetic field is on, this turning continues, caus... |
What makes radioactive atoms get old so quickly and decay? | Atoms don't age. Atoms radioactively decay when a lower-energy nuclear configuration exists to which they can transition. The actual decay event of an individual atom happens randomly and is not the result of the atom getting old or changing through time. The phrases "getting old" or "aging" are rather vague and could... | tag/atom/ | context: tag/atom/ question: What makes radioactive atoms get old so quickly and decay? | Atoms don't age. Atoms radioactively decay when a lower-energy nuclear configuration exists to which they can transition. The actual decay event of an individual atom happens randomly and is not the result of the atom getting old or changing through time. The phrases "getting old" or "aging" are rather vague and could... |
Why do atoms always contain the same number of electrons and protons? | Atoms do not always contain the same number of electrons and protons, although this state is common. When an atom has an equal number of electrons and protons, it has an equal number of negative electric charges (the electrons) and positive electric charges (the protons). The total electric charge of the atom is there... | tag/atom/ | context: tag/atom/ question: Why do atoms always contain the same number of electrons and protons? | Atoms do not always contain the same number of electrons and protons, although this state is common. When an atom has an equal number of electrons and protons, it has an equal number of negative electric charges (the electrons) and positive electric charges (the protons). The total electric charge of the atom is there... |
Why don't atoms collapse if they are mostly empty space? | Atoms are not mostly empty space because there is no such thing as purely empty space. Rather, space is filled with a wide variety of particles and fields. Sucking all the particles and fields out of a certain volume won't make the space completely empty because new particles will still flash into existence due to vac... | tag/atom/ | context: tag/atom/ question: Why don't atoms collapse if they are mostly empty space? | Atoms are not mostly empty space because there is no such thing as purely empty space. Rather, space is filled with a wide variety of particles and fields. Sucking all the particles and fields out of a certain volume won't make the space completely empty because new particles will still flash into existence due to vac... |
Why don't electrons in the atom enter the nucleus? | Electrons in the atom do enter the nucleus. In fact, electrons in the s states tend to peak at the nucleus. Electrons are not little balls that can fall into the nucleus under electrostatic attraction. Rather, electrons are quantized wavefunctions that spread out in space and can sometimes act like particles in limite... | tag/atom/ | context: tag/atom/ question: Why don't electrons in the atom enter the nucleus? | Electrons in the atom do enter the nucleus. In fact, electrons in the s states tend to peak at the nucleus. Electrons are not little balls that can fall into the nucleus under electrostatic attraction. Rather, electrons are quantized wavefunctions that spread out in space and can sometimes act like particles in limite... |
Why don't metals burn? | Metals do burn. In fact, most metals release a lot of heat when they burn and are hard to put out. For example, thermite is used to weld train rails together. The fuel in thermite is the metal aluminum. When thermite burns, the aluminum atoms bond with oxygen atoms to form aluminum oxide, releasing a lot of heat and l... | tag/atom/ | context: tag/atom/ question: Why don't metals burn? | Metals do burn. In fact, most metals release a lot of heat when they burn and are hard to put out. For example, thermite is used to weld train rails together. The fuel in thermite is the metal aluminum. When thermite burns, the aluminum atoms bond with oxygen atoms to form aluminum oxide, releasing a lot of heat and l... |
Are there different types of black holes? | Yes, there are different types of black holes. The most straightforward way to classify black holes is according to their mass. You may think that because a black hole is in essence just a clump of matter that is dense enough to trap light, black holes of all masses should exist. In other words, black holes should exi... | tag/black-hole/ | context: tag/black-hole/ question: Are there different types of black holes? | Yes, there are different types of black holes. The most straightforward way to classify black holes is according to their mass. You may think that because a black hole is in essence just a clump of matter that is dense enough to trap light, black holes of all masses should exist. In other words, black holes should exi... |
Can you go fast enough to get enough mass to become a black hole? | Traveling at high speed does not affect your mass, even in Einstein's theory of Special Relativity. For some reason, pre-college teachers, popular science books, and older physics textbooks claim that objects gain mass when they are traveling at higher speeds. This claim is wrong. If you define something called "relat... | tag/black-hole/ | context: tag/black-hole/ question: Can you go fast enough to get enough mass to become a black hole? | Traveling at high speed does not affect your mass, even in Einstein's theory of Special Relativity. For some reason, pre-college teachers, popular science books, and older physics textbooks claim that objects gain mass when they are traveling at higher speeds. This claim is wrong. If you define something called "relat... |
Does every black hole contain a singularity? | In the real universe, no black holes contain singularities. In general, singularities are the non-physical mathematical result of a flawed physical theory. When scientists talk about black hole singularities, they are talking about the errors that appear in our current theories and not about objects that actually exis... | tag/black-hole/ | context: tag/black-hole/ question: Does every black hole contain a singularity? | In the real universe, no black holes contain singularities. In general, singularities are the non-physical mathematical result of a flawed physical theory. When scientists talk about black hole singularities, they are talking about the errors that appear in our current theories and not about objects that actually exis... |
How can there be anything left in the universe? Don't black holes suck everything in? | Black holes don't suck everything in. Black holes have gravity in the same ways stars have gravity. For this reason, planets orbit safely around black holes in the same way they orbit around our sun. The only difference between a black hole and a star is that the black hole has a small enough radius that light inside ... | tag/black-hole/ | context: tag/black-hole/ question: How can there be anything left in the universe? Don't black holes suck everything in? | Black holes don't suck everything in. Black holes have gravity in the same ways stars have gravity. For this reason, planets orbit safely around black holes in the same way they orbit around our sun. The only difference between a black hole and a star is that the black hole has a small enough radius that light inside ... |
How does a black hole give off light? | A black hole itself does not give off any light. That is why it is called black. However, matter that is near a black hole can give off light in response to the black hole's gravity.
A black hole is a region of space where gravity is so strong that nothing can escape, not even light. It might be surprising to you t... | tag/black-hole/ | context: tag/black-hole/ question: How does a black hole give off light? | A black hole itself does not give off any light. That is why it is called black. However, matter that is near a black hole can give off light in response to the black hole's gravity.
A black hole is a region of space where gravity is so strong that nothing can escape, not even light. It might be surprising to you t... |
How does a supernova completely destroy a star? | A supernova does not completely destroy a star. Supernovae are the most violent explosions in the universe. But they do not explode like a bomb explodes, blowing away every bit of the original bomb. Rather, when a star explodes into a supernova, its core survives. The reason for this is that the explosion is caused by... | tag/black-hole/ | context: tag/black-hole/ question: How does a supernova completely destroy a star? | A supernova does not completely destroy a star. Supernovae are the most violent explosions in the universe. But they do not explode like a bomb explodes, blowing away every bit of the original bomb. Rather, when a star explodes into a supernova, its core survives. The reason for this is that the explosion is caused by... |
Is a black hole a 2D or a 3D object? | A black hole is actually a four-dimensional object. A black hole extends across all four physical dimensions of the universe. The four dimensions that form the background framework of the universe consist of three spatial dimensions and one time dimension. These four dimensions are inseparably connected into one unifi... | tag/black-hole/ | context: tag/black-hole/ question: Is a black hole a 2D or a 3D object? | A black hole is actually a four-dimensional object. A black hole extends across all four physical dimensions of the universe. The four dimensions that form the background framework of the universe consist of three spatial dimensions and one time dimension. These four dimensions are inseparably connected into one unifi... |
Where is the center of the universe? | According to all current observations, there is no center to the universe. For a center point to exist, that point would have to somehow be special with respect to the universe as a whole. Let us think about all the different types of effects that could create a center. First, if an object is rotating, you can define ... | tag/black-hole/ | context: tag/black-hole/ question: Where is the center of the universe? | According to all current observations, there is no center to the universe. For a center point to exist, that point would have to somehow be special with respect to the universe as a whole. Let us think about all the different types of effects that could create a center. First, if an object is rotating, you can define ... |
Why does everything in our galaxy orbit the supermassive black hole at the center? | Strictly speaking, everything in our galaxy does not orbit the supermassive black hole at the center. Everything in the galaxy orbits the center of mass of the galaxy. The supermassive black hole just happens to be at the center. If the black hole at the center were removed, the galactic orbits of almost all objects i... | tag/black-hole/ | context: tag/black-hole/ question: Why does everything in our galaxy orbit the supermassive black hole at the center? | Strictly speaking, everything in our galaxy does not orbit the supermassive black hole at the center. Everything in the galaxy orbits the center of mass of the galaxy. The supermassive black hole just happens to be at the center. If the black hole at the center were removed, the galactic orbits of almost all objects i... |
Do blind people dream in visual images? | Yes, blind people do indeed dream in visual images. For people who were born with eyesight and then later went blind, it is not surprising that they experience visual sensations while dreaming. Dreams are drawn from memories that are stored in the brain as well as from brain circuitry that is developed while experienc... | tag/brain/ | context: tag/brain/ question: Do blind people dream in visual images? | Yes, blind people do indeed dream in visual images. For people who were born with eyesight and then later went blind, it is not surprising that they experience visual sensations while dreaming. Dreams are drawn from memories that are stored in the brain as well as from brain circuitry that is developed while experienc... |
Do scientists have a hard time understanding art? | Actually, scientists tend to be more art-minded than your average person. Science is a highly creative process, and so it tends to attract people who innately understand art, appreciate art, and create art. The old notion goes that one half of the brain is highly creative and the other half of the brain is highly tech... | tag/brain/ | context: tag/brain/ question: Do scientists have a hard time understanding art? | Actually, scientists tend to be more art-minded than your average person. Science is a highly creative process, and so it tends to attract people who innately understand art, appreciate art, and create art. The old notion goes that one half of the brain is highly creative and the other half of the brain is highly tech... |
How bad of an alcoholic do you have to be to have your brain affected? | One drink of alcohol is enough to affect your brain, whether you are an alcoholic or a casual social drinker. Alcohol is a psychoactive drug that interferes directly with the normal functioning of many parts of the brain. Fortunately, much of the effect caused by alcohol consumption can be repaired by the body when th... | tag/brain/ | context: tag/brain/ question: How bad of an alcoholic do you have to be to have your brain affected? | One drink of alcohol is enough to affect your brain, whether you are an alcoholic or a casual social drinker. Alcohol is a psychoactive drug that interferes directly with the normal functioning of many parts of the brain. Fortunately, much of the effect caused by alcohol consumption can be repaired by the body when th... |
How can we unlock the 90% of our brain that we never use? | Healthy humans use all of their brain. There is no part of the brain that goes unused. Certain tasks work certain parts of the brain more, but they all play important roles, as explained by neurobiologist Dr. Eric Chudler. Brain maps, as found in modern anatomy books, indicate that each part of the brain has a specifi... | tag/brain/ | context: tag/brain/ question: How can we unlock the 90% of our brain that we never use? | Healthy humans use all of their brain. There is no part of the brain that goes unused. Certain tasks work certain parts of the brain more, but they all play important roles, as explained by neurobiologist Dr. Eric Chudler. Brain maps, as found in modern anatomy books, indicate that each part of the brain has a specifi... |
How do I turn on more parts of my brain and get smarter? | Turning on more parts of your brain does not make you smarter. The brain does not really work that way. An example of a brain experiencing high activation is a seizure. During a seizure, a person has severely decreased functioning and mental capability. A person having a seizure can't talk, can't walk, and can't do ma... | tag/brain/ | context: tag/brain/ question: How do I turn on more parts of my brain and get smarter? | Turning on more parts of your brain does not make you smarter. The brain does not really work that way. An example of a brain experiencing high activation is a seizure. During a seizure, a person has severely decreased functioning and mental capability. A person having a seizure can't talk, can't walk, and can't do ma... |
How do nerves control every organ and function in the body? | Nerves do not control every tissue and function in the human body, although they do play a large role. There are three main ways that bodily organs and functions are controlled: Nerves carry orders from the brain and spinal cord in the form of electrical signals. Nerves also help sense the state of tissues and relay t... | tag/brain/ | context: tag/brain/ question: How do nerves control every organ and function in the body? | Nerves do not control every tissue and function in the human body, although they do play a large role. There are three main ways that bodily organs and functions are controlled: Nerves carry orders from the brain and spinal cord in the form of electrical signals. Nerves also help sense the state of tissues and relay t... |
How does ice cream in your stomach cause a headache? | An ice cream headache has nothing to do with your stomach, but is rather the result of the roof of your mouth (your palate) getting cold too quickly. In fact, you can get an ice cream headache before even swallowing the ice cream. Ice cream headaches occur whenever you eat or drink something cold too rapidly, and they... | tag/brain/ | context: tag/brain/ question: How does ice cream in your stomach cause a headache? | An ice cream headache has nothing to do with your stomach, but is rather the result of the roof of your mouth (your palate) getting cold too quickly. In fact, you can get an ice cream headache before even swallowing the ice cream. Ice cream headaches occur whenever you eat or drink something cold too rapidly, and they... |
How long can you use a cell phone before getting a brain tumor? | Cell phones do not cause cancer, no matter how long they are used, because they communicate using radio waves. Radio waves simply don't have enough energy per photon to ionize atoms. The World Health Organization states, "Only the high frequency portion of the electromagnetic spectrum, which includes X rays and gamma ... | tag/brain/ | context: tag/brain/ question: How long can you use a cell phone before getting a brain tumor? | Cell phones do not cause cancer, no matter how long they are used, because they communicate using radio waves. Radio waves simply don't have enough energy per photon to ionize atoms. The World Health Organization states, "Only the high frequency portion of the electromagnetic spectrum, which includes X rays and gamma ... |
What part of the brain is hurt when you get headaches? | Most headaches have nothing to do with the brain being damaged or strained. There is more to your head than your brain. Surrounding your brain are meninges, bones, muscles, skin layers, lymph nodes, blood vessels, the eyes, ears, mouth, nose and cavities called sinuses. Most headaches are caused by strain or pressure ... | tag/brain/ | context: tag/brain/ question: What part of the brain is hurt when you get headaches? | Most headaches have nothing to do with the brain being damaged or strained. There is more to your head than your brain. Surrounding your brain are meninges, bones, muscles, skin layers, lymph nodes, blood vessels, the eyes, ears, mouth, nose and cavities called sinuses. Most headaches are caused by strain or pressure ... |
Why are human brains the biggest? | The brains of humans are not the biggest compared to all other animals. The average human brain has a mass of about 1 kg. In contrast, the brain of a sperm whale has a mass of 8 kg and that of an elephant has a mass of 5 kg. You may be tempted to think that bigger brains means smarter and that because humans are the s... | tag/brain/ | context: tag/brain/ question: Why are human brains the biggest? | The brains of humans are not the biggest compared to all other animals. The average human brain has a mass of about 1 kg. In contrast, the brain of a sperm whale has a mass of 8 kg and that of an elephant has a mass of 5 kg. You may be tempted to think that bigger brains means smarter and that because humans are the s... |
Why does a person with only one working eye have zero depth perception? | Having only one working eye does not lead to zero depth perception. Although using two eyes does indeed play a large role in depth perception, there are also many other approaches that the human visual system uses to perceive depth. In general, approaches that enable depth perception are called "depth perception cues"... | tag/brain/ | context: tag/brain/ question: Why does a person with only one working eye have zero depth perception? | Having only one working eye does not lead to zero depth perception. Although using two eyes does indeed play a large role in depth perception, there are also many other approaches that the human visual system uses to perceive depth. In general, approaches that enable depth perception are called "depth perception cues"... |
Did cancer exist before man-made chemicals were around to create it? | Yes, cancer existed long before humans were able to create synthetic substances that cause cancer (cancer-causing agents are called "carcinogens"). Unfortunately, cancer is a natural part of life. Every multicellular creature on earth can get cancer, even in the remotest locations (yes, even sharks get cancer). While ... | tag/cancer/ | context: tag/cancer/ question: Did cancer exist before man-made chemicals were around to create it? | Yes, cancer existed long before humans were able to create synthetic substances that cause cancer (cancer-causing agents are called "carcinogens"). Unfortunately, cancer is a natural part of life. Every multicellular creature on earth can get cancer, even in the remotest locations (yes, even sharks get cancer). While ... |
How do 5G cell phone signals harm humans? | The electromagnetic waves from all cell phone systems, including 5G systems, cause zero harm to humans. All cell phones and cell phone towers use radio waves to communicate. Radio waves have been in use for wireless communications for over a hundred years with no credible evidence of adverse health effects. The radio ... | tag/cancer/ | context: tag/cancer/ question: How do 5G cell phone signals harm humans? | The electromagnetic waves from all cell phone systems, including 5G systems, cause zero harm to humans. All cell phones and cell phone towers use radio waves to communicate. Radio waves have been in use for wireless communications for over a hundred years with no credible evidence of adverse health effects. The radio ... |
How much extra radiation am I exposed to if I stick my hand in the microwave right after it turns off? | You are actually exposed to less radiation if you stick your hand in a properly functioning microwave oven right after it turns off. First of all, the microwaves emitted by a microwave oven are not harmful beyond their ability to heat you. Microwaves are non-ionizing, meaning that they do not have enough energy per ph... | tag/cancer/ | context: tag/cancer/ question: How much extra radiation am I exposed to if I stick my hand in the microwave right after it turns off? | You are actually exposed to less radiation if you stick your hand in a properly functioning microwave oven right after it turns off. First of all, the microwaves emitted by a microwave oven are not harmful beyond their ability to heat you. Microwaves are non-ionizing, meaning that they do not have enough energy per ph... |
Is ionizing radiation always harmful? | No, ionizing radiation is only harmful to an organism as a whole when its amount gets too high. We are constantly bombarded with very small amounts of ionizing radiation that occur naturally, and we get along just fine with our lives without being seriously harmed by this radiation. There are trace amounts of naturall... | tag/cancer/ | context: tag/cancer/ question: Is ionizing radiation always harmful? | No, ionizing radiation is only harmful to an organism as a whole when its amount gets too high. We are constantly bombarded with very small amounts of ionizing radiation that occur naturally, and we get along just fine with our lives without being seriously harmed by this radiation. There are trace amounts of naturall... |
Why are cancer mortality rates rising? | Cancer mortality rates are not rising. They are dropping. For instance, data from the World Health Organization shows that 26% fewer U.S. middle-aged men died of cancer in 2010 than in 1975. For U.S. middle-aged women, the cancer mortality in the same time period has dropped 19%. Surprisingly, the deaths due to corona... | tag/cancer/ | context: tag/cancer/ question: Why are cancer mortality rates rising? | Cancer mortality rates are not rising. They are dropping. For instance, data from the World Health Organization shows that 26% fewer U.S. middle-aged men died of cancer in 2010 than in 1975. For U.S. middle-aged women, the cancer mortality in the same time period has dropped 19%. Surprisingly, the deaths due to corona... |
Why don't dark-skinned people get sunburns? | Dark-skinned people do get sunburns. While it's true that the higher pigment levels that make certain people's skin look dark helps protect against sunlight, the pigments do not block 100% of the light. The skin pigment melanin is produced by special skin cells called melanocytes to protect the body from the damaging ... | tag/cancer/ | context: tag/cancer/ question: Why don't dark-skinned people get sunburns? | Dark-skinned people do get sunburns. While it's true that the higher pigment levels that make certain people's skin look dark helps protect against sunlight, the pigments do not block 100% of the light. The skin pigment melanin is produced by special skin cells called melanocytes to protect the body from the damaging ... |
Why isn't there just one cure for cancer? | There is not one cure or treatment for cancer because cancer is not a single disease. The word "cancer" is an umbrella term that includes hundreds of different diseases. Furthermore, cancer is typically harder to battle than infectious disease because there is no foreign agent attacking the body which can be distingui... | tag/cancer/ | context: tag/cancer/ question: Why isn't there just one cure for cancer? | There is not one cure or treatment for cancer because cancer is not a single disease. The word "cancer" is an umbrella term that includes hundreds of different diseases. Furthermore, cancer is typically harder to battle than infectious disease because there is no foreign agent attacking the body which can be distingui... |
Do I weigh less on the equator than at the North Pole? | Yes, you weigh less on the equator than at the North or South Pole, but the difference is small. Note that your body itself does not change. Rather it is the force of gravity and other forces that change as you approach the poles. These forces change right back when you return to your original latitude. In short, a tr... | tag/centrifugal/ | context: tag/centrifugal/ question: Do I weigh less on the equator than at the North Pole? | Yes, you weigh less on the equator than at the North or South Pole, but the difference is small. Note that your body itself does not change. Rather it is the force of gravity and other forces that change as you approach the poles. These forces change right back when you return to your original latitude. In short, a tr... |
How do space ships make artificial gravity? | Despite the fact that outer space is brimming with gravity, the lack of solid ground in space means that objects without thrust are in a continual state of free fall, and free fall feels just like zero gravity. To stop all objects in a space ship from floating around due to their free fall motion, you would need artif... | tag/centrifugal/ | context: tag/centrifugal/ question: How do space ships make artificial gravity? | Despite the fact that outer space is brimming with gravity, the lack of solid ground in space means that objects without thrust are in a continual state of free fall, and free fall feels just like zero gravity. To stop all objects in a space ship from floating around due to their free fall motion, you would need artif... |
Why is the centrifugal force talked about so much if it's not real? | The centrifugal force is very real if you are in a rotating reference frame. It causes objects in a rotating frame of reference to accelerate away from the center of rotation. Washing machines, uranium enrichment centrifuges, and biology lab centrifuges all depend on the reality of the centrifugal force . However, the... | tag/centrifugal/ | context: tag/centrifugal/ question: Why is the centrifugal force talked about so much if it's not real? | The centrifugal force is very real if you are in a rotating reference frame. It causes objects in a rotating frame of reference to accelerate away from the center of rotation. Washing machines, uranium enrichment centrifuges, and biology lab centrifuges all depend on the reality of the centrifugal force . However, the... |
How do scientists cool objects to absolute zero? | Nothing can be cooled to a temperature of exactly absolute zero. The temperature of an object is a measure of the average random motion energy (kinetic energy) of its atoms. Absolute zero is the temperature at which all of an object's atoms have been brought to a dead stop relative to each other. This temperature is d... | tag/cold/ | context: tag/cold/ question: How do scientists cool objects to absolute zero? | Nothing can be cooled to a temperature of exactly absolute zero. The temperature of an object is a measure of the average random motion energy (kinetic energy) of its atoms. Absolute zero is the temperature at which all of an object's atoms have been brought to a dead stop relative to each other. This temperature is d... |
What makes space so cold? | Space is not always cold. It depends if you are facing the sun or not. And even if you are in shadow, space is not cold in the sense that it will cool you down quickly. The part of an astronaut facing the sun becomes blazing hot while the side in shadow remains a moderate temperature due to the suits internal machiner... | tag/cold/ | context: tag/cold/ question: What makes space so cold? | Space is not always cold. It depends if you are facing the sun or not. And even if you are in shadow, space is not cold in the sense that it will cool you down quickly. The part of an astronaut facing the sun becomes blazing hot while the side in shadow remains a moderate temperature due to the suits internal machiner... |
When I step out of the shower, what makes the tile floor so much colder than the bathroom mat? | Assuming you don't plug in your bathroom mat to turn on an internal heater, the mat is the same temperature as the tile floor. Everything in the room is at about the same temperature: room temperature. The tiles conduct heat much better than the fluffy mat, which means they suck heat out of your feet much faster. This... | tag/cold/ | context: tag/cold/ question: When I step out of the shower, what makes the tile floor so much colder than the bathroom mat? | Assuming you don't plug in your bathroom mat to turn on an internal heater, the mat is the same temperature as the tile floor. Everything in the room is at about the same temperature: room temperature. The tiles conduct heat much better than the fluffy mat, which means they suck heat out of your feet much faster. This... |
Why do cold temperatures give you a cold? | Cold temperatures can affect your health, but they don't directly give you an infection like the common cold. Infections are caused by bacteria, fungi, and viruses. Rhinoviruses are the usual cause of the common cold, as laid out by Ronald Eccles in his book "Common Cold". In order to make you feel sick, an infectious... | tag/cold/ | context: tag/cold/ question: Why do cold temperatures give you a cold? | Cold temperatures can affect your health, but they don't directly give you an infection like the common cold. Infections are caused by bacteria, fungi, and viruses. Rhinoviruses are the usual cause of the common cold, as laid out by Ronald Eccles in his book "Common Cold". In order to make you feel sick, an infectious... |
Why don't trees freeze and burst in the winter like cold pipes? | In many cases, trees do partially freeze in the cold of winter and burst like plumbing pipes in an unheated home. When liquid water freezes to ice, it expands in volume because of the way the water molecules spread out to form a solid crystalline lattice. If the water is contained in a closed vessel, it can press so h... | tag/cold/ | context: tag/cold/ question: Why don't trees freeze and burst in the winter like cold pipes? | In many cases, trees do partially freeze in the cold of winter and burst like plumbing pipes in an unheated home. When liquid water freezes to ice, it expands in volume because of the way the water molecules spread out to form a solid crystalline lattice. If the water is contained in a closed vessel, it can press so h... |
Can humans ever directly see a photon? | Yes. In fact, photons are the only things that humans can directly see. A photon is a bit of light. Human eyes are specifically designed to detect light. This happens when a photon enters the eye and is absorbed by one of the rod or cone cells that cover the retina on the inner back surface of the eye. When you look a... | tag/color/ | context: tag/color/ question: Can humans ever directly see a photon? | Yes. In fact, photons are the only things that humans can directly see. A photon is a bit of light. Human eyes are specifically designed to detect light. This happens when a photon enters the eye and is absorbed by one of the rod or cone cells that cover the retina on the inner back surface of the eye. When you look a... |
Can you make a sunset in a cup of milk? | Yes, you can make a sunset in a cup of milk. The same orange and red pattern of colors that you see when the sun goes down can be created in your cup of milk if you set up the situation properly. The physics that makes your cup of milk orange and red is the exact same physics that makes the sky at sunset orange and re... | tag/color/ | context: tag/color/ question: Can you make a sunset in a cup of milk? | Yes, you can make a sunset in a cup of milk. The same orange and red pattern of colors that you see when the sun goes down can be created in your cup of milk if you set up the situation properly. The physics that makes your cup of milk orange and red is the exact same physics that makes the sky at sunset orange and re... |
Does the back of a rainbow look the same as its front side? | A rainbow does not have a back side. If you were to walk completely to the other side of the mist cloud that is creating the rainbow and turn around, you would not see a rainbow. You have to realize that a rainbow is not a stationary physical object. Instead, it is a pattern of light that becomes a stable image only w... | tag/color/ | context: tag/color/ question: Does the back of a rainbow look the same as its front side? | A rainbow does not have a back side. If you were to walk completely to the other side of the mist cloud that is creating the rainbow and turn around, you would not see a rainbow. You have to realize that a rainbow is not a stationary physical object. Instead, it is a pattern of light that becomes a stable image only w... |
Have astronomers ever observed a violet shift like they have blue shifts and red shifts? | Violet shifts happen all the time. We call them blue shifts. When a star emits light, the color of its light as observed on earth depends on its motion relative to earth. If a star is moving towards the earth, its light is shifted to higher frequencies on the color spectrum (towards the green/blue/violet/ultraviolet/x... | tag/color/ | context: tag/color/ question: Have astronomers ever observed a violet shift like they have blue shifts and red shifts? | Violet shifts happen all the time. We call them blue shifts. When a star emits light, the color of its light as observed on earth depends on its motion relative to earth. If a star is moving towards the earth, its light is shifted to higher frequencies on the color spectrum (towards the green/blue/violet/ultraviolet/x... |
How do projectors project the color black? | Projectors do not project the color black. This makes sense since black is really the absence of light, and you can't project something that does not exist. When a projector sends a beam of light on to a wall or a projector screen so that an image is formed on the wall or screen, the parts of the image that look black... | tag/color/ | context: tag/color/ question: How do projectors project the color black? | Projectors do not project the color black. This makes sense since black is really the absence of light, and you can't project something that does not exist. When a projector sends a beam of light on to a wall or a projector screen so that an image is formed on the wall or screen, the parts of the image that look black... |
How does plasma make a campfire flame orange? | The de-excitation of plasma (charged gas) is not the source of the light given off by a campfire's flame. The incandescence of solid soot particles billowing up on an updraft of hot air is what creates the light seen as a flame. Let us look at the typical ways materials emit light and then apply it to the campfire. El... | tag/color/ | context: tag/color/ question: How does plasma make a campfire flame orange? | The de-excitation of plasma (charged gas) is not the source of the light given off by a campfire's flame. The incandescence of solid soot particles billowing up on an updraft of hot air is what creates the light seen as a flame. Let us look at the typical ways materials emit light and then apply it to the campfire. El... |
Is a quadruple rainbow possible? | Yes, although very rare, it is possible for a human to see four natural rainbows at once in the sky. A rainbow occurs when white sunlight scatters off of raindrops in the air. Because of the dispersive properties of water, the different colors of light in the sunlight bend (refract) different amounts when entering and... | tag/color/ | context: tag/color/ question: Is a quadruple rainbow possible? | Yes, although very rare, it is possible for a human to see four natural rainbows at once in the sky. A rainbow occurs when white sunlight scatters off of raindrops in the air. Because of the dispersive properties of water, the different colors of light in the sunlight bend (refract) different amounts when entering and... |
Is human blood ever any color other than red? | Yes, human blood is green in the deep ocean. We have to be careful about what we mean by color. Objects don't really have an intrinsic color. Rather, the color of an object is determined by three factors: 1) the color content of the incident light that is illuminating the object; 2) the way the object reflects, absorb... | tag/color/ | context: tag/color/ question: Is human blood ever any color other than red? | Yes, human blood is green in the deep ocean. We have to be careful about what we mean by color. Objects don't really have an intrinsic color. Rather, the color of an object is determined by three factors: 1) the color content of the incident light that is illuminating the object; 2) the way the object reflects, absorb... |
What is it about red that makes bulls so angry? | The color red does not make bulls angry. In fact, bulls are partially color blind compared to healthy humans, so that they cannot see red. According to the book "Improving Animal Welfare" by Temple Grandin, cattle lack the red retina receptor and can only see yellow, green, blue, and violet colors. Color vision in mam... | tag/color/ | context: tag/color/ question: What is it about red that makes bulls so angry? | The color red does not make bulls angry. In fact, bulls are partially color blind compared to healthy humans, so that they cannot see red. According to the book "Improving Animal Welfare" by Temple Grandin, cattle lack the red retina receptor and can only see yellow, green, blue, and violet colors. Color vision in mam... |
What is it about the ocean that makes it look blue when it reflects the sky? | The ocean is not blue just because it reflects the sky. The ocean is mostly blue because water itself is blue. In a Journal of Chemical Education paper titled "Why Is Water Blue?" by Charles L. Braun and Sergei N. Smirnov, water is shown to have a slight intrinsic blue color. It takes a large quantity of water, like i... | tag/color/ | context: tag/color/ question: What is it about the ocean that makes it look blue when it reflects the sky? | The ocean is not blue just because it reflects the sky. The ocean is mostly blue because water itself is blue. In a Journal of Chemical Education paper titled "Why Is Water Blue?" by Charles L. Braun and Sergei N. Smirnov, water is shown to have a slight intrinsic blue color. It takes a large quantity of water, like i... |
What is the color of the sun? | The color of the sun is white. The sun emits all colors of the rainbow more or less evenly and in physics, we call this combination "white". That is why we can see so many different colors in the natural world under the illumination of sunlight. If sunlight were purely green, then everything outside would look green o... | tag/color/ | context: tag/color/ question: What is the color of the sun? | The color of the sun is white. The sun emits all colors of the rainbow more or less evenly and in physics, we call this combination "white". That is why we can see so many different colors in the natural world under the illumination of sunlight. If sunlight were purely green, then everything outside would look green o... |
Why are red, yellow, and blue the primary colors in painting but computer screens use red, green, and blue? | Red, yellow, and blue are not the main primary colors of painting, and in fact are not very good primary colors for any application. First of all, you can define any colors you want to be the "primary colors" of your color system, so that other colors are obtained by mixing the primary colors. Although there may be an... | tag/color/ | context: tag/color/ question: Why are red, yellow, and blue the primary colors in painting but computer screens use red, green, and blue? | Red, yellow, and blue are not the main primary colors of painting, and in fact are not very good primary colors for any application. First of all, you can define any colors you want to be the "primary colors" of your color system, so that other colors are obtained by mixing the primary colors. Although there may be an... |
Why are there only six fundamental colors: red, orange, yellow, green, blue, and violet? | There are an infinite number of fundamental colors, if by "fundamental" you mean "spectral". Spectral colors are also known loosely as rainbow colors. A spectral color is composed of a single fundamental color on the visible part of the electromagnetic spectrum, as opposed to a mixture of colors. Spectral colors such ... | tag/color/ | context: tag/color/ question: Why are there only six fundamental colors: red, orange, yellow, green, blue, and violet? | There are an infinite number of fundamental colors, if by "fundamental" you mean "spectral". Spectral colors are also known loosely as rainbow colors. A spectral color is composed of a single fundamental color on the visible part of the electromagnetic spectrum, as opposed to a mixture of colors. Spectral colors such ... |
Why are veins blue? | The veins themselves are not blue, but are mostly colorless. It is the blood in the veins that gives them color. Furthermore, the blood in human veins is also not blue. Blood is always red. Blood that has been oxygenated (mostly flowing through the arteries) is bright red and blood that has lost its oxygen (mostly flo... | tag/color/ | context: tag/color/ question: Why are veins blue? | The veins themselves are not blue, but are mostly colorless. It is the blood in the veins that gives them color. Furthermore, the blood in human veins is also not blue. Blood is always red. Blood that has been oxygenated (mostly flowing through the arteries) is bright red and blood that has lost its oxygen (mostly flo... |
Why can't color blind people see any colors? | Most people with color blindness can see almost all colors. They are typically only blind to a few colors. Furthermore, they are not completely blind to those colors, but are only partially blind. The human eye contains three types of color detecting cells: red-detecting cones, green-detecting cones, and blue-detectin... | tag/color/ | context: tag/color/ question: Why can't color blind people see any colors? | Most people with color blindness can see almost all colors. They are typically only blind to a few colors. Furthermore, they are not completely blind to those colors, but are only partially blind. The human eye contains three types of color detecting cells: red-detecting cones, green-detecting cones, and blue-detectin... |
Why does a rainbow contain a pure spread of spectral colors? | A rainbow does not contain a pure spread of spectral colors, although it is somewhat close. A spectral color is a color that contains only one wavelength component of its electromagnetic wave. In contrast, a non-spectral color contains many wavelengths and is therefore a mixture of spectral colors. Simple lasers produ... | tag/color/ | context: tag/color/ question: Why does a rainbow contain a pure spread of spectral colors? | A rainbow does not contain a pure spread of spectral colors, although it is somewhat close. A spectral color is a color that contains only one wavelength component of its electromagnetic wave. In contrast, a non-spectral color contains many wavelengths and is therefore a mixture of spectral colors. Simple lasers produ... |
Why does a rainbow exist only in a narrow band? | A rainbow does not exist only in a narrow band. A primary rainbow is the light pattern resulting from sunlight entering a spherical water drop, bouncing once off the back of the drop, and exiting. Defined this way, a primary rainbow exists at all viewing angles from 0° to 42° and therefore forms a wide disc. The viewi... | tag/color/ | context: tag/color/ question: Why does a rainbow exist only in a narrow band? | A rainbow does not exist only in a narrow band. A primary rainbow is the light pattern resulting from sunlight entering a spherical water drop, bouncing once off the back of the drop, and exiting. Defined this way, a primary rainbow exists at all viewing angles from 0° to 42° and therefore forms a wide disc. The viewi... |
Why does water make a shirt darker? | Getting a spot wet on your shirt does not make that spot permanently darker or intrinsically different. Water just makes fabric appear darker by making the fabric more transparent, allowing you to see darker objects behind the fabric. Let's first consider a white shirt. The individual fibers that make up a white shirt... | tag/color/ | context: tag/color/ question: Why does water make a shirt darker? | Getting a spot wet on your shirt does not make that spot permanently darker or intrinsically different. Water just makes fabric appear darker by making the fabric more transparent, allowing you to see darker objects behind the fabric. Let's first consider a white shirt. The individual fibers that make up a white shirt... |
Why doesn't the outside world appear blue even though so much light comes from the blue sky? | Actually, a lot of the outside world on a sunny day is tinted blue because of the blue sky. The blue tinting of the outside world is quite striking if you know how to look for it. Sunlight that has just left the sun contains a relatively equal mix of all spectral colors and is therefore white. When the sunlight passes... | tag/color/ | context: tag/color/ question: Why doesn't the outside world appear blue even though so much light comes from the blue sky? | Actually, a lot of the outside world on a sunny day is tinted blue because of the blue sky. The blue tinting of the outside world is quite striking if you know how to look for it. Sunlight that has just left the sun contains a relatively equal mix of all spectral colors and is therefore white. When the sunlight passes... |
Why is the sky blue? | If you look in any popular science book on this topic, it will tell you that the sky is blue because of Rayleigh scattering in the atmosphere. While Rayleigh scattering is a very important part of the answer, it is not the only part. If the only effect at work were Rayleigh scattering, then the sky would be violet, no... | tag/color/ | context: tag/color/ question: Why is the sky blue? | If you look in any popular science book on this topic, it will tell you that the sky is blue because of Rayleigh scattering in the atmosphere. While Rayleigh scattering is a very important part of the answer, it is not the only part. If the only effect at work were Rayleigh scattering, then the sky would be violet, no... |
Why was color invented by humans? | Color was not invented by humans. Color is a fundamental physical property of light that exists independent of humans. How color is perceived by a certain person is of course human dependent. For example, a standard helium-neon laser always emits a specific red color (scientifically, its color is the color with a wave... | tag/color/ | context: tag/color/ question: Why was color invented by humans? | Color was not invented by humans. Color is a fundamental physical property of light that exists independent of humans. How color is perceived by a certain person is of course human dependent. For example, a standard helium-neon laser always emits a specific red color (scientifically, its color is the color with a wave... |
Can momentum be hidden to human eyes like how kinetic energy can be hidden as heat? | Yes and no. In a regular mechanical system with macroscopic parts, momentum can not be "hidden" to human eyes. But in other systems, momentum can be hidden. For instance, in an electromagnetic system, momentum can be transferred to the electromagnetic field, which is invisible to human eyes at most frequencies. Theref... | tag/conservation-of-energy/ | context: tag/conservation-of-energy/ question: Can momentum be hidden to human eyes like how kinetic energy can be hidden as heat? | Yes and no. In a regular mechanical system with macroscopic parts, momentum can not be "hidden" to human eyes. But in other systems, momentum can be hidden. For instance, in an electromagnetic system, momentum can be transferred to the electromagnetic field, which is invisible to human eyes at most frequencies. Theref... |
How can we travel to the past? | Mainstream science dictates that time travel to the past is impossible. The basic problem with time travel to the past is conservation of energy. For example, pretend I made a time travel portal that sends objects back three seconds in time to the exact same location, and I mount this portal a few inches above a tramp... | tag/conservation-of-energy/ | context: tag/conservation-of-energy/ question: How can we travel to the past? | Mainstream science dictates that time travel to the past is impossible. The basic problem with time travel to the past is conservation of energy. For example, pretend I made a time travel portal that sends objects back three seconds in time to the exact same location, and I mount this portal a few inches above a tramp... |
How do free energy machines work? | Free energy machines do not work. No machine can create energy out of nothing, as this would violate the law of mass-energy conservation, which is fundamental and universal. The law of mass-energy conservation states that mass-energy can never be created or destroyed. It can only be redistributed throughout space and ... | tag/conservation-of-energy/ | context: tag/conservation-of-energy/ question: How do free energy machines work? | Free energy machines do not work. No machine can create energy out of nothing, as this would violate the law of mass-energy conservation, which is fundamental and universal. The law of mass-energy conservation states that mass-energy can never be created or destroyed. It can only be redistributed throughout space and ... |
How do levers create energy if the conservation of energy does not allow energy to be created? | Levers do not create energy. Levers convert a small force applied over a long distance to a large force applied over a small distance. Work is the force times the distance, W = Fd, so the total work done is the same with or without the lever. Look closely at a lever as you use it. The end that lifts the fridge moves a... | tag/conservation-of-energy/ | context: tag/conservation-of-energy/ question: How do levers create energy if the conservation of energy does not allow energy to be created? | Levers do not create energy. Levers convert a small force applied over a long distance to a large force applied over a small distance. Work is the force times the distance, W = Fd, so the total work done is the same with or without the lever. Look closely at a lever as you use it. The end that lifts the fridge moves a... |
How does quantum theory allow a rock to turn suddenly into a duck? | Quantum theory does not allow a rock to turn suddenly into a duck. It does not allow any other bizarre transformation to happen either. This idea is a myth perpetuated by people who misunderstand quantum theory. Foundational to quantum theory is the concept of particle uncertainty. It is impossible to know a particle'... | tag/conservation-of-energy/ | context: tag/conservation-of-energy/ question: How does quantum theory allow a rock to turn suddenly into a duck? | Quantum theory does not allow a rock to turn suddenly into a duck. It does not allow any other bizarre transformation to happen either. This idea is a myth perpetuated by people who misunderstand quantum theory. Foundational to quantum theory is the concept of particle uncertainty. It is impossible to know a particle'... |
Why is mass conserved in chemical reactions? | Mass is not conserved in chemical reactions. The fundamental conservation law of the universe is the conservation of mass-energy. This means that the total mass and energy before a reaction in a closed system equals the total mass and energy after the reaction. According to Einstein's famous equation, E = mc2, mass ca... | tag/conservation-of-energy/ | context: tag/conservation-of-energy/ question: Why is mass conserved in chemical reactions? | Mass is not conserved in chemical reactions. The fundamental conservation law of the universe is the conservation of mass-energy. This means that the total mass and energy before a reaction in a closed system equals the total mass and energy after the reaction. According to Einstein's famous equation, E = mc2, mass ca... |
How do tractor beams work? | Up until recently, tractor beams (beams of light that tow objects) existed only in the world of science fiction. While large-scale tractor beams that can tow space ships are still machines of the future, microscopic tractor beams are here today. The idea at first seams to defy physics. Shoot light at an object and the... | tag/conservation-of-momentum/ | context: tag/conservation-of-momentum/ question: How do tractor beams work? | Up until recently, tractor beams (beams of light that tow objects) existed only in the world of science fiction. While large-scale tractor beams that can tow space ships are still machines of the future, microscopic tractor beams are here today. The idea at first seams to defy physics. Shoot light at an object and the... |
If I'm on an elevator that breaks loose and plummets down the shaft, can I avoid harm by jumping at the last second? | First of all, elevators never plummet down their shafts. For the past century, elevators have had a backup break that automatically engages when an elevator starts to fall. If all the cables snapped (highly unlikely), the elevator would only fall a few feet before the safety breaks would activate. The safety breaks ar... | tag/conservation-of-momentum/ | context: tag/conservation-of-momentum/ question: If I'm on an elevator that breaks loose and plummets down the shaft, can I avoid harm by jumping at the last second? | First of all, elevators never plummet down their shafts. For the past century, elevators have had a backup break that automatically engages when an elevator starts to fall. If all the cables snapped (highly unlikely), the elevator would only fall a few feet before the safety breaks would activate. The safety breaks ar... |
Why are truck drivers rude? | Truck drivers are professional operators and are therefore less rude on the road in general than your typical driver. Truck drivers are often perceived to be rude for one simple reason: inertia. Inertia (also called "momentum" or "Newton's First Law") means that an object in motion tends to stay in motion and resists ... | tag/conservation-of-momentum/ | context: tag/conservation-of-momentum/ question: Why are truck drivers rude? | Truck drivers are professional operators and are therefore less rude on the road in general than your typical driver. Truck drivers are often perceived to be rude for one simple reason: inertia. Inertia (also called "momentum" or "Newton's First Law") means that an object in motion tends to stay in motion and resists ... |
Why doesn't light carry momentum? | Light does carry momentum. Momentum can be thought of as an object's ability to push another object due to its motion. Classically, momentum is defined as the mass of the object times the velocity of the object, p = mv. Since light has no mass, you may be tempted to say that light has no momentum. Additionally, everyd... | tag/conservation-of-momentum/ | context: tag/conservation-of-momentum/ question: Why doesn't light carry momentum? | Light does carry momentum. Momentum can be thought of as an object's ability to push another object due to its motion. Classically, momentum is defined as the mass of the object times the velocity of the object, p = mv. Since light has no mass, you may be tempted to say that light has no momentum. Additionally, everyd... |
Could electronic devices charge themselves without being plugged into an electricity source? | Yes, electronic devices can charge their batteries through various methods without being plugged into a source of electricity. What all the different methods have in common is that they absorb energy that is in some other form (heat, light, vibrations, radio waves, etc.) from the external environment and then convert ... | tag/electricity/ | context: tag/electricity/ question: Could electronic devices charge themselves without being plugged into an electricity source? | Yes, electronic devices can charge their batteries through various methods without being plugged into a source of electricity. What all the different methods have in common is that they absorb energy that is in some other form (heat, light, vibrations, radio waves, etc.) from the external environment and then convert ... |
Does a source of electricity ever run out of electrons? | The answer to this question depends on the situation. We can roughly classify all electrical systems into two categories: static electricity systems and circuit electricity systems. Note that all electrical effects are actually part of one unified set of physical laws. This classification is therefore ultimately arbit... | tag/electricity/ | context: tag/electricity/ question: Does a source of electricity ever run out of electrons? | The answer to this question depends on the situation. We can roughly classify all electrical systems into two categories: static electricity systems and circuit electricity systems. Note that all electrical effects are actually part of one unified set of physical laws. This classification is therefore ultimately arbit... |
How much money do I save by recharging my cell phone at work? | By consistently recharging your cell phone at work (where your employer pays for electricity) instead of at home (where you pay for electricity), you save less than 50 cents a year. According to Wikipedia, the iPhone 5 has a battery that can hold 0.00545 kiloWatt-hours of energy (about 20 kilojoules). Therefore, if yo... | tag/electricity/ | context: tag/electricity/ question: How much money do I save by recharging my cell phone at work? | By consistently recharging your cell phone at work (where your employer pays for electricity) instead of at home (where you pay for electricity), you save less than 50 cents a year. According to Wikipedia, the iPhone 5 has a battery that can hold 0.00545 kiloWatt-hours of energy (about 20 kilojoules). Therefore, if yo... |
What is the speed of electricity? | The speed of electricity really depends on what you mean by the word "electricity". This word is very general and basically means, "all things relating to electric charge". I will assume we are referring to a current of electrical charge traveling through a metal wire, such as through the power cord of a lamp. In the ... | tag/electricity/ | context: tag/electricity/ question: What is the speed of electricity? | The speed of electricity really depends on what you mean by the word "electricity". This word is very general and basically means, "all things relating to electric charge". I will assume we are referring to a current of electrical charge traveling through a metal wire, such as through the power cord of a lamp. In the ... |
Why can't lightning strike the same place twice? | Lightning does strike the same place twice. Lighting tends to strike the highest and pointiest object, because it is an electrical current being attracted to the easiest path. If your church steeple is on a hill, it is going to be struck many times. The Empire State Building in New York City gets struck by lightning 1... | tag/electricity/ | context: tag/electricity/ question: Why can't lightning strike the same place twice? | Lightning does strike the same place twice. Lighting tends to strike the highest and pointiest object, because it is an electrical current being attracted to the easiest path. If your church steeple is on a hill, it is going to be struck many times. The Empire State Building in New York City gets struck by lightning 1... |
Why do car tires protect you from lightning strikes? | Car tires do not protect you from lightning strikes. Although the rubber in a tire acts as an insulator at low voltages, the voltage in a lighting bolt is far too high to be stopped by tires or air. No matter how thick your tires are, they don't stop lightning according to physicist Martin Uman in his book "All About ... | tag/electricity/ | context: tag/electricity/ question: Why do car tires protect you from lightning strikes? | Car tires do not protect you from lightning strikes. Although the rubber in a tire acts as an insulator at low voltages, the voltage in a lighting bolt is far too high to be stopped by tires or air. No matter how thick your tires are, they don't stop lightning according to physicist Martin Uman in his book "All About ... |
Why does lightning push electricity through air, but common batteries do not? | Actually, a common low-voltage battery does push a small electrical current through the air. But this current is so small that in most cases it can be ignored. Nevertheless, an unconnected battery does slowly leak electricity through the air and will eventually end up uncharged if left sitting long enough (internal ch... | tag/electricity/ | context: tag/electricity/ question: Why does lightning push electricity through air, but common batteries do not? | Actually, a common low-voltage battery does push a small electrical current through the air. But this current is so small that in most cases it can be ignored. Nevertheless, an unconnected battery does slowly leak electricity through the air and will eventually end up uncharged if left sitting long enough (internal ch... |
Why is a 12-volt household battery harmless, but the shock from a 12-volt car battery will kill you? | The shock from a car battery will not kill you. In fact, under normal conditions, a 12-volt car battery will usually not even shock you. Car batteries are not harmless, though. There are many ways you can be injured by car batteries: There are enough dangers present that it is a good idea to be cautious around car bat... | tag/electricity/ | context: tag/electricity/ question: Why is a 12-volt household battery harmless, but the shock from a 12-volt car battery will kill you? | The shock from a car battery will not kill you. In fact, under normal conditions, a 12-volt car battery will usually not even shock you. Car batteries are not harmless, though. There are many ways you can be injured by car batteries: There are enough dangers present that it is a good idea to be cautious around car bat... |
Why were electrons chosen to be negatively charged? Wouldn't it make more sense to call electrons positively charged because when they move they make electricity? | First of all, "electricity" does not mean "moving electric charge". If "electricity" meant "moving electric charge" then "static electricity" would mean "stationary moving electric charge," which is nonsense. "Electricity" is a general term describing all effects connected to electric charges. When people use the word... | tag/electricity/ | context: tag/electricity/ question: Why were electrons chosen to be negatively charged? Wouldn't it make more sense to call electrons positively charged because when they move they make electricity? | First of all, "electricity" does not mean "moving electric charge". If "electricity" meant "moving electric charge" then "static electricity" would mean "stationary moving electric charge," which is nonsense. "Electricity" is a general term describing all effects connected to electric charges. When people use the word... |
How can it be so hard to drag rubber across smooth glass if friction is caused by surface roughness? | Friction is not caused mainly by surface roughness. According to the book "Sliding Friction" by Bo N. J. Persson, friction is caused by weak electromagnetic forces between molecules, such as experienced in hydrogen bonds and Van der Waal bonds. If two electrically neutral, non-polar atoms are brought close enough toge... | tag/electromagnetism/ | context: tag/electromagnetism/ question: How can it be so hard to drag rubber across smooth glass if friction is caused by surface roughness? | Friction is not caused mainly by surface roughness. According to the book "Sliding Friction" by Bo N. J. Persson, friction is caused by weak electromagnetic forces between molecules, such as experienced in hydrogen bonds and Van der Waal bonds. If two electrically neutral, non-polar atoms are brought close enough toge... |
How do magnets heal? | Magnets have no healing properties. Magnetic Resonance Imaging (MRI) employs very strong magnetic fields, far stronger than a household magnet can produce, and yet MRI's have no direct effect on the health of the patient (an MRI may have an indirect effect as a diagnostic tool). The iron in our blood is in far too low... | tag/electromagnetism/ | context: tag/electromagnetism/ question: How do magnets heal? | Magnets have no healing properties. Magnetic Resonance Imaging (MRI) employs very strong magnetic fields, far stronger than a household magnet can produce, and yet MRI's have no direct effect on the health of the patient (an MRI may have an indirect effect as a diagnostic tool). The iron in our blood is in far too low... |
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