Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: Zeig on 13/10/2006 00:22:13
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Simply what matter makes up light? At the speed it travels how does it not hurt us at all? why doesn't it go through us and we then just fall apart? Why does it bounce off of our skin, is it becuase it's density is far too small?
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HI ZIEG
Anybody please feel free to correct any error i 've made but i think its about right . [:)]
Light (Radiation from the sun ) the full electromagnetic spectrum is made up of massless particle's called photons which come to us from the sun as part of a spectrum comprised of different wavelengths, the smaller the wave length the higher its energy. some wave lengths we cansee some we cant. we for instance cant see ultraviolet light but bees can so the visible part of the spectrum is dependent on what creature is viewing it.
Some wavelengths like gamma rays are so small and have such high energy they can literally pass straight through your body but as they do and because they are so small they can actually interact with the individual electrons in your atoms which make up your body ionizing your tissue by literally knocking the electrons of the atoms.
Longer Wavelengths like x rays are still high in energy and small enough to pass through and ionize your tissue but not as much as gamma rays. but as bone atoms are large compared to the other atoms makng up your body and happen to be about the same size as the wavelength of an x-ray some times the energy of the x-ray is absorbed by the bone atom which raises its energy level, as the atom returns to it normal energy level an equal amount of energy to that which was absorbed is thrown back out (or something like that) allowing us to view an image of our our skeleton when used in conjunction with an x-ray machine which can detect the x-rays being returned .
Visible light waves are quite long are to low in energy to pass through your skin and so bounce off lighting things up and are a very small part electromagnetic spectrum. Each visible wavelength has a different colour, red has the longest wavelength violet has the shortest and when you put all the visible wave lengths together it produces white light . You can view the individual visible wavelengths of light in a rainbow or by looking through a prism...
So you see light does interact with our bodies, some wavelengths like the visible part of the spectrum are long in wavelength and low in energy and so bounce off us lighting us up during the day ,some shorter and higher wave lengths can enter the outer layers of our skin burning us and causing damage to our skin cells when we spend too much time in the summer sun and some wavelengths can go straight through our bodies doing damaging to the individual atoms of your body as they travel through.
Michael
Michael
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http://imagers.gsfc.nasa.gov/ems/waves3.html
Michael
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okay i still don't get some of it though. So if photons are massles that means there is no mass, which means hey are made of..well nothing? How does nothingtravel and how does nothing have energy. how do we see the "nothing"? Is light still somthing but just not somuch made of atoms as it is a element all to itself off the periodic table?
srry, i liked ur explanation tho.
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quote:
Originally posted by Zeig
okay i still don't get some of it though. So if photons are massles that means there is no mass, which means hey are made of..well nothing? How does nothingtravel and how does nothing have energy. how do we see the "nothing"? Is light still somthing but just not somuch made of atoms as it is a element all to itself off the periodic table?
What atoms are made of? Energy and other particles (energy IS mass). What the other particles are made of? Energy and other particles...
So when you say "nothing" you are talking about energy, that is, you are actually talking about...everything!
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Light is a form of moving energy. it is electromagnetic radiation.
Let me explain it from absolute first principles
A stationary electrical charge (for example a paticle like an electron) creates an electrical field around itself just like mass creates a gravitiational field but an electrical field is much stronger than a gravitational one. A moving electrical charge therefore creates a varying electrical field now a varying electrical field creates a magnetic field. The magnetism in a magnet is caused by lots of electrons creating moving electrical fields as they orbit round the nucleii of atoms and if the material is suitable they can all line up to produce a magnet. Now if I take a magnet and move it around I can create an electrical field (This is donein a generator to generate electricity).
Right now I have shown from familiar things, that a moving electrical field can create a magnetic field and a moving magnetic field can produce an electrical one (all this requires no massive material around) so if the conditions are right moving magnetic fields can create moving electrical fields which in turn create moving magnetic fields and so on to produce what is called electromagnetic waves. These waves of energy travel at the velocity of light through the vacuum of space.
I hope this helps
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