No, light is not matter, light is energy, but matter and energy are related, and in certain situations, at very high energies such as inside a star or particle collider, matter can be converted into energy and vice versa. Photons have no mass, but matter has mass. Photons are "quanta" (tiny bits) of electromagnetic energy. Light is very interesting in that it behaves either like waves or like particles, depending on how you measure it. Photons travel all the way across the universe at the speed of light! Matter cannot ever travel at the speed of light. So, we know that light cannot *be* matter, at least not in the form we know it (gross matter - like rocks, plants, animals, people, and stuff). The term "light" is usually used to mean the small portion of all electromagnetic radiation that we can see with our eyes, but there is a tremendous range of electromagnetic radiation that goes from very long wavelengths (radio frequency waves) to extremely short, high energy waves (gamma rays). This range we call the Electromagnetic Spectrum. Light that you can see is not in matter, but all living matter contains energy. You are warm, right? So your body emits heat energy (we call this infra red radiation) and electrical energy because of all our brain and nerve impulses. If you look at a person using an infra red camera, you can see the warmer and cooler areas of their body. All planets contain heat energy, too, and we can measure their heat output by observing them in infra red, microwave, or radio frequencies. But at extremely high temperatures and energies, matter and radiation become interchangeable. Matter can be converted into energy, such as in nuclear fusion. Einstein predicted this in his famous equation E = mc2 where m stands for mass and c is the speed of light, and I write c2 to mean "c squared". This takes place inside stars, and that is how they shine - by converting some of their matter to energy Energy can be converted into matter in very extreme conditions, such as in the very early universe (we're talking within the first one to three minutes after the so-called Big Bang). At first, the universe was all radiation. At a certain moment it cooled down so that protons could condense out of the radiation, and shortly afterwards it cooled enough so that electrons could condense. But at that time of extreme heat and light (trillions of degrees, unimaginable!) matter AND antimatter condensed out of the radiation field! So, for a few more minutes, there was an equilibrium reaction going on, of matter and antimatter condensing out of the radiation field, and then recombining into pure energy, because (maybe you have heard this) matter + antimatter annihilate each other into pure energy (photons). Then, a short time later, the universe cooled enough so that this equilibrium reaction stopped. The last bit of matter and antimatter formed out of the radiation, and mutually annihilated each other. Luckily for us, the balance between matter and antimatter was not equal, and there was extra matter left over from this last annihilation, and so that is why we are here today! Here is another bit of 'extreme' information that you can tell your class: If you could magically transform yourself so that you could ride on a photon traveling across the universe, you would see that all the space in front of you would be contracted down to no distance at all, and you would not experience the passage of time! Of course you cannot really do this, because you are made of matter. I hope this helps you win the debate! Best wishes, Author unknown. .
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