then, how do photons do it? I mean, in physics class, we were taught, that to move something at constant speed, you need constant unchanging force. So how can something apply to one section of the universe and not another?
2007-11-01 03:32:13 · 11 answers · asked by Anonymous in Science & Mathematics ➔ Astronomy & Space
Because light isn't just a photon - it's also a form of energy.
Light is only in photon form when you observe it - otherwise, it's a wave. And either way, as photons or as waves, light does not have mass.
It takes infinite force to move anything with mass at the speed of light. Since light has no mass, it takes no energy to move it at the speed of light.
Now, photons DO have momentum. Momentum, in the case of light (or any other form of electromagnetic radiation), is related to its frequency. The higher the frequency, the higher the momentum.
2007-11-01 03:38:44 · answer #1 · answered by Brian L 7 · 2⤊ 0⤋
It takes infinite force to accelerate a mass to the speed of light. How much mass does a photon have?
You think "that to move something at constant speed, you need constant unchangeing force." But you weren't taught that.
2007-11-01 14:54:41 · answer #2 · answered by Mark 6 · 0⤊ 0⤋
Shame on you physics teacher for making you think that, "to move something at constant speed, you need constant unchanging force". That is TOTALLY false. Newton's first law says that WITH NO FORCE ON IT, any object in motion will continue at the same velocity forever. You are merely fooled by the force of friction which is always operating in normal every day situations.
But light is a special case because photons are pure energy; they have no mass. And they cannot exist at all unless they are moving at exactly the speed of light.
2007-11-01 11:39:07 · answer #3 · answered by campbelp2002 7 · 2⤊ 0⤋
According to my own Fractal Foam Model of Universes, all massive particles consist of photons orbiting one another (pushed together by dark energy). The photons within a particle are moving at the speed of light, even when the particle is stationary. The mass of the particle is the energy of the component photons divided by c^2. To accelerate the particle, you must increase the energy of each photon within the particle.
Don't expect to find this in any text book, yet. Maybe the scientific community will wake up to this fact in another century or two.
2007-11-01 15:37:20 · answer #4 · answered by Anonymous · 0⤊ 0⤋
Inside every photon is a little man on a exercise bike, pedalling *very* fast.
Okay this question has been resolved really so let's try this explanation:
As you approach the speed of light, time gets slower and slower compared with the rest of the universe. For example if you had 2 twins and one stayed on earth and the other zoomed off at close to the speed of light then the astronaut twin wouldn't age much. If after 70 years of earth time she came back then her earthbound twin would be 70 years older but she would be much younger than this. Now consider a more extreme version of this: suppose she somehow left at the speed of light went to alpha centauri and came back. During her journey she would become infinitely massive, completely flat, and her time would have slowed down to a standstill. She wouldn't have aged a day! For her the whole journey would be instantaneous. As far as she is concerned, she just teleported there got out stuck her flag on some asteroid and teleported back again. Her twin would have aged 9.2 years however, because Alpha Centauri is about 4.6 light years away. Can we say photons are teleporting around then? From our point of view we see them moving from a to b to c to d, from their point of view they are teleporting about instantaneously? How do they do it? They are cheating!
2007-11-01 11:30:53 · answer #5 · answered by some_pixels_on_a_screen 3 · 0⤊ 0⤋
"we were taught, that to move something at constant speed, you need constant unchanging force."
You may want to talk to your teacher about this. A constant net force leads to constant acceleration - so by definition not a constant speed.
With regards to your question, photons do not have mass.
2007-11-01 10:39:59 · answer #6 · answered by BNP 4 · 3⤊ 1⤋
It takes infinite force to move a massive object at the speed of light.
"Massive" here means: having rest mass.
Photons have zero rest mass. All particles with zero rest mass always travel at the speed of light.
By the way, it is not absolutely certain that photons have a rest mass of exactly zero---it could just be really, really, really tiny. Then their speed would tend to always be very close to the speed of light, but would never reach it exactly.
2007-11-01 10:43:00 · answer #7 · answered by cosmo 7 · 1⤊ 1⤋
"I mean, in physics class, we were taught, that to move something at constant speed, you need constant unchanging force."
Did you flunk that class?
2007-11-01 10:50:50 · answer #8 · answered by ZikZak 6 · 0⤊ 0⤋
Photons have zero mass.. That simple. Objects of mass require force to move them. Objects of zero mass do not.
2007-11-01 10:42:18 · answer #9 · answered by Anonymous · 0⤊ 0⤋
Photons are considered to be massless or nearly massless.
And it's not an infinate force its C2
Light speed squared
I guess you can say it's Maxim's Maxim
Water finds its own level
Photons NATURALLY travel at light speed
It's in their NATURE
You have MASS then GRAVITY pulls you back
You have no mass it takes a LOT of gravity (black hole) to keep you down.
Anything less and you go out at light speed.
All I can tell you is that I believe a TACHYON is possible and it goes FASTER than light speed.
I refuse to say it's impossible.
That is unscientific.
2007-11-01 10:41:36 · answer #10 · answered by Anonymous · 0⤊ 3⤋