About Energy...

Energy doesn''t actually exist. It''s an abstraction used in the mathematics of physics to understand how particles interact. Potential energy for instance is a way to measure how much force an object CAN interact with. However, if you look at planet earth and ask how much potential energy is has in regard to attracting all other mass in the universe towards it, and the number you get is astonomical, if not infinite (if the universe is indeed infinite).

Now, you ask, how does E=mc^2 then, if theres no such thing as energy? Einstein''s formula tells you how much energy is required to maintain a certain amount of mass. Nuclear reactions don''t create energy, but rather remove bonding energy between particles, which become expressed in other ways. Namely immense heat and radiation.

Batteries?! A battery is a chemical concotion which is easy to relate to a spring. The chemicals in a battery act to store energy. By creating a circuit around them, a "potential difference" is created across the circuit and the chemicals inside begin acting. When the chemicals have sufficiently interacted and run out of ways to interact (become inert relative to each other), the potential difference disappears.

If you pay attention, it seems that everything in the universe is accounted for, which we call the Conservation theories.

quote: Original post by Kars
0 * 0 = light speed?

Actually, it''s more like

1/((u0)(e0)) = speed of light

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The only problem I have with this theory is that if something has no mass how would you ever perceive it? It would pass right through anything attempting to measure it. If you said that photons had VERY little mass and thus VERY little energy to accelerate, I could agree with you there.

It has momentum, just not mass. Check out the momentum of a wave (I''d have to look it up).

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I have always though of energy as being something that you can only "see" through something with mass during time. Energy would be the acting of an object through space for a certain amount of time, i.e. gravity pulling the apple to the ground, coil rotating in a magnetic field to produce electricity (which is basically electrons moving from one point to another), etc.

Look into wave-particle duality (inparticular, with respect to light).

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So what you see would not be energy directly but the mass that the energy acts on. So if you see it, can it really be energy as well?

Really, you only "see" photons. When a photon hits your retina it gives up its energy, creating the series of electrical impulses... ask a biologist for the rest. Also,

E0 = mc2

gives an objects "rest energy". That is, it gives the energy an object has "stored" as mass when at rest (i.e. in the same frame of reference as the observer).

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It takes an infinite amount of energy to push/pull something to a finite speed?

Yeah, crazy, isn''t it? c is the speed limit of the universe.

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I guess you could explain this through the math equation where if you keep adding half the previous number to itself, it only ever gets so big (cna''t remember the specific name for this equation). I.e.

1 1 1 1 1 1
(2 * -) + (1 * -) + ( - * -) + ( - * -) ... will never reach 2
2 2 2 2 4 2

Actually, you could show it with the lorentz transformations, but your infinite geometric series would be a good way yo get a handle on the idea.

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Something traveling at the speed of light can go no other speed? So how is it then that we have shadows? Wouldn''t the light travel right through the object?

No, light bounces off objects. (Actually, I think it''s a little more complicated than that, but classical optics isn''t wrong)

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If it bounces off another object, are you saying that friction never slows it down and that zero time is lost by the direction change?

I believe this is basically true.

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If light emanates from a source (i.e. a sun) where did it start since it can never travels slower then light?

It started in the sun.

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Is it spontaneously created? Travel in very tight circles until it is let go?

Spontaneously created would be correct. When you excite an electron (give it energy), it''ll generally release that energy (things don''t tend to like being excited) in the form of a photon.

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I found a table on the internet of the speed of light through different mediums:
Medium Speed of Light in Medium
speed of light in a vacuum is 299 792 458 m/s
speed of light in air is 299 702 547 m/s
speed of light in ice 228 849 204 m/s
what is the speed of light in water 225 407 863 m/s
what is the speed of light in glass 199 861 638 m/s

I think it has to do with a photon being more likely to interact with an atom in certain media.

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Not being facetious with the questions, just want to know what the hang up is on saying that you can''t travel faster than the speed of light.

The Mickelson-Morley experiment shows that light always appears to travel at the same speed. Look up the "light clock" thought experiments.

I''d explain light clocks and such, but it''s late and I need sleep tonight. Someone else could probably do a better job (and clean up any mistakes I''ve made above, or even errors due to my ignorance of anything beyond basic modern physics)

The thing about Light is that its an electromagnetic phenomena. A moving electrical current produces a moving magnetic fields with produces a moving electrical current. The antenna is a device created to produce and detect magnetic fields, which are used to produce "signals." The human retina is designed to detect-only moving electrical currents that are oscillating between two frequencies, Red and Blue. If you take an antenna and get it to produce a moving magnetic field at a high enough frequency, humans can see it, we call this the incandecent filament lightbulb, of which you probably have one several feet above your head.

Now, because of the conservation theorems, and using your knowledge of physics, and a little math, you can work out with pen and paper the speed that light must be moving at. The thinking is that if you have light moving at any other speeds then the power of the electromagnetic signal logarytmically disappears, or extends into infinite, which doesn't happen. This speed, the speed of light in a vacuum, is the accepted C. The speed of light in a medium is slower because of the time it takes for an electron to absorb the light, move into an excited orbit, emit the light, and move back to it's natural orbit. In more dense mediums, there are a lot more electrons that need to do this. As for shiny metal versus course dirt, the electrons reemit the light based on many different factors, which produces the image quality of a particular object.

As for C being the speed limit on the universe, though it's never been proven, theres a logical reason for it to occur. Its called the "Mass Increase." Its been determined in accelerators and even in common televisions that increasing speed increases mass, to conserve mass-inertia or momentum. With an increase in mass, you have a slight increase in gravity among the subatomic particles. Ever so slight. As you approach C, Mass increases, Volume decreases. The theoretical end result is that the electrons and the protons get too close, and bind to form neutrons. However, its important to note that modern physics "falls apart" under speeds faster then C. That just means the math needs way more tinkering. This includes needing infinite energy to reach C. It should be noted however, that it does require more energy to accelerate things that have more mass, so we do have a logarythmic formula here.

[edited by - inmate2993 on August 9, 2003 12:40:01 PM]

About shadowing. Whole universe is actually a very dark place. Very, very dark place. When a photon hits atom, it deflects one of the electrons out of his orbit (some say that they, electrons, have no orbit but a potential orbit(they MAY appear there)), electron releases energy (being moved from high-energy orbit to low-energy). That energy, if treated as a wave, has its freq, and thus, it can become another photon (not become, it already is). And so on. All of you have seen this effect. It''s commonly named raytracing.

We don''t actually see dark places because dark places cannot be seen. We see results of photon collision with cells in our eye balls. If no photon arrived from that direction, there is no color in certain cells.

You can imagine eye as an array of charges (for color and brightness). Cells are kept at value zero (no charge) all the time. If they are hit by a photon, they are charged for some time (don''t know how long). brain is forming pictura by composing charges he receives (each cell has parts for color channel and for brightness, don''t know their name on English);

EDIT : fixed grammar