If nothing can reach the speed of light, how does light manage to do it? I know this sounds like I'm being flippant but I'm serious. Light travels through a vacuum and can be affected by gravity so there has to be physical substance to it.
2007-02-19 05:02:59 · 6 answers · asked by Anonymous in Science & Mathematics ➔ Physics
Nothing can EXCEED the speed of light, not REACH the speed of light. By definition the speed of light is the speed that photons travel.
There is indeed a substance to light (thanks to wave-particle duality)... this can be demonstrated by the fact that a powerful light can move a mirror suspended in a vacuum.
2007-02-19 05:08:04 · answer #1 · answered by Anonymous · 0⤊ 0⤋
Have you taken a beginning physics class? Light is made up of tiny packets of energy (photons) that travel in a straight line. I figure there has to be some kind of mass to these packets because as you said, gravity affects how light travels.
The funny thing about these photons is that although they do travel in a straight line, they don't.... They're called electromagnetic "waves" for a reason. Like ripples in a pond, the photons move up/down... and straight out from the light source.
Regarding your first question about how photons gains enough velocity to reach the speed of light... I don't know- I think it's the release of energy when electrons start bouncing between energy-levels that gets the photons going.
A thought- if photons are what light is made up of, then what kind of damage can a photon torpedo do?... a killer sunburn??
2007-02-19 13:17:09 · answer #2 · answered by Yoda's Duck 6 · 0⤊ 0⤋
Light travels at the speed it does because that's how fast space will carry it. The speed of light in a vacuum is due to properties of space itself. Light is electromagnetic radiation - fluctuating electric and magnetic fields, not a substance. Light is affected by gravity because gravity warps the space the light is traveling through, not because gravity attracts photons.
2007-02-19 13:13:45 · answer #3 · answered by injanier 7 · 0⤊ 0⤋
The equations of relativity allow for a little loophole. An object with no mass can travel at the speed of light. This loophole is pretty weak, and most physicists probably wouldn't believe in massless particles that always travel at light speed if it weren't for one big example that we see in nature. The photon! Light is affected by gravity, but not because it has mass. According to general relativity, the spacetime around massive objects is curved and the light just takes a curved path through the curved spacetime.
2007-02-19 13:19:01 · answer #4 · answered by Link 5 · 1⤊ 1⤋
You second assertion is entirely false.
Massive and massless particles are both affected by gravity, as is energy. In fact, gravity is indistinguishable from an accelerating reference frame (the principle of equivalence), and so acts equally on absolutely everything physical.
In general relativistic terms it is stress energy not mass that is the source of gravity.
2007-02-19 13:12:11 · answer #5 · answered by Anonymous · 0⤊ 0⤋
This depends on what your reference point is.
In Newtonian physics, only massless particles can move at the speed of light, a category which includes light.
In relativity, everything moves at the speed of light. Here, the only problem would be how you might develop an understanding of what this means and why it is so.
2007-02-19 13:41:13 · answer #6 · answered by Fred 7 · 0⤊ 1⤋