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 According
to special relativity, the speed of light is fastest speed that anything
can go. No object can travel faster.
This is the old laws of Galileo and Newton.
Here I am in these pictures. Picture A shows me spitting a fireball standing.
Picture B shows me spitting a fireball flying.
When I am spitting a firefall flying,
it goes farther than it does when I'm standing still because the flight
power adds speed to the fireball.
This is called Galileo's Addition law
of velocities. It says that if I fly at 20 mph and I can spit a fireball
on the ground 25 mph, the total speed of the fireball while I'm flying
is 45.
In the 19th century a famous scientist
named Maxwell published his theories of light. He said that the speed
of light is always at 300,000,000 meters per second, no matter what.
This violated Galileo's law because that meant that you can't add speed
to light. Here is what I mean.
In these photos, I'm sending off light
through my flashlight. Picture A: I am on the ground, and picture B:
I am flying. Observe the speed of the light beams.
You can see that there is no difference
in the speed of the light. So no matter how fast I fly, I can't add
speed to light.
In a famous experiment by Michelson
proved this correct. Many people tried to find an explanation of why
you can't make light go faster. Einstein's explaination (his special
realitivity) was the best. He said:
Light moves through empty space at
certain speed. The motion of the source does not affect the speed
of light. The motion of someone watching also does not affect the
speed of light.
If you are running away from light,
the speed of light approaches you in the same speed as if you are sitting.
This may be hard to accept, but it's a very important fact. This is
his second postulate(law) of relativity. I'll tell you the first later.
Einstein's theory of special relativity
has a lot to do about the speed of light. Because that is where the
original theories makes the mistakes. You will see that close to the
speed of light, a lot of things change.
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