Did Einstein contradict himself?
I woke up this morning thinking about Einstein’s Theory of Relativity.
–Einstein said that time goes slower if you travel at the speed of light–186,000 miles per second.
–Einstein also said that the speed of light is a constant–that it never changes.
–However, since speed is a factor of time; if time slows down at the speed of light, then a second would take longer and therefore the speed of light would be faster.
–In other words, if time is relative, then the speed of light (which is based on time) would also be relative and if it is relative it can’t be constant.
And if the speed of light is not “C” (constant); how can Energy equal mass times the speed of light squared (E = MC squared)? Would that make Einstein’s famous formula an oxymoron?
What do you think?
(After writing this I went to see the movie, Black or White, staring Kevin Costner and Octavia Spencer. As the film began to run, one word appeared on the screen in giant letters — Relativity.) It looked like this:
Pingback: A Poem & Some Quotes About Conscience | Free Gas For Your Think Tank (A blog to jog your mind and unclog your heart . . .)
This seems to be a misunderstanding of the term “constant.” A constant is something that, by its very definition, cannot change. The speed of light is a number that is fixed, while velocity is something that can change. What actually happens when an observer approaches the speed of light is that time “dilates”, but length also “contracts.” In other words, the things that we once thought were “constants” — time, length, etc. — actually change so that the speed of light remain a constant value. What’s interesting about relativity, as Einstein pointed out, is that if you were on Earth or even on a rocket ship that was traveling almost the speed of light, then both people would measure that the speed of light is c.
So, it’s two things: c is just a number and always will be. However, the reason that light always travels at that speed is because time dilates — like you pointed out –, but length also contracts for someone moving close to the speed of light. In other words, nature doesn’t treat things like time, length, mass, etc. as constants; instead, it keeps the speed of light constant and “changes” everything else so that the speed of light remain a constant.
His formula E=mc^2 is also not “technically” correct. At least, it could be if either of two assumptions are made:
1.) There was a, now outdated, term called “relativistic mass” that we don’t use anymore, so there should actually be a greek letter “gamma” in front of the m to make this correct called the “Lorentz factor.”
2.) The other thing is that this formula would be correct if its just the “rest mass” energy; in other words, the energy of a particle when it’s not moving. If a particle has momentum, then it has more energy.
The more correct equation — that he came up with, but is not as widely known in everyday culture — is E^2 = p^2c^2 + m^2c^4. So, if p = 0, then you get E = mc^2 again.
One other thing to mention, too, is that light is technically not always constant. When people say that the speed of light is c, what they mean is that it will be c when its in a vacuum or “empty space.” If you shine light into something like a liquid, for instance, light will actually travel less than c. However, if you ignored all of the “messy stuff” like liquids and such, then light will just travel at c. Hope that helps!
Very helpful! Thank you.
Not a problem! God bless.