# Thread: need opinion on the concept of general relativity

1. ## need opinion on the concept of general relativity

I was watching dscie channel. titled known universe, using speed as a key to unlock the secrets of the universe. so here's the part that astounds me.

a car goes east at 50 mph. a truck goes west at 50mph. they pass each other. the relative speed of the truck to the car is 100mph.

a car goes east at 50 mph. a truck goes east at 60mph. they pass each other. the relative speed of the truck to the car is 10mph.

cool right!'

now i am in a space ship x, traveling in a direction A. my speed is 182,000mps.
another space ship y, is going in the same direction at the speed of light 186,000mps

what is the relative speed ship y is traveling as observed by ship x?

answer = 186,000mps the speed of light and if they went in the opposite direction the answer stays the same! what changes is space-time!

And we use this theory every day. GPS satellites travel 7000mph in orbit so the time is adjusted or the coordinates would be off by 7 miles!

so the faster you drive, the younger you will be relative to those standing still! what do you think about that????

my question is do we really know the speed of light is the fastest thing?

2. hmmmmmm.

3. It depends on if you define velocity "locally", or if you define velocity using "comoving coordinates".

If you define velocity using "comoving coordinates", you can correctly (if I am not mistaken) make the claim that certain galaxies in our expanding universe are propogating away from us at a velocity which exceeds c, the speed of light. I may be making an erroneous claim here, though.

4. there are galaxies traveling faster than the speed of light. at the big bang, everything expanded faster than light. light is simply a constant. light can be slowed to almost a stand still. at harvard. it has been done experimentally.

5. I'm fascinated about the concept of time biological versus mechanical as well. I'm more interested in our human perceptions of time and how music/film graphic art stretchs time like an elastic, yet still following mathematical patterns.

jhope-- I didn't know that light could be slow down to a standstill. physics has always fascinated as much as it has confused me. now, light can be quantified as both waves and particles right? So if photons can be frozen experimentally -- do they take the form of a wave?Wavical?

6. they took sodium gas to near absolute 0. 2 clouds. they sent a laser into the tube. when the photons hit the gas atoms, the atom absorbed it then transmited it to rhe next. light changes speed in different mediums. like water or glass. that's why it bends. 124,000mps water, 186,000mps vaccuum. i wish i understood this stuff but the math is beyond me. the cool thing is we see 13.5 billion light years in a perfect sphere. but if we moved over to the edge of the sphere, we would see 13.5 billion light years in a perfect sphere from that point and the previous point would be the edge on one side and you could see another 13.5 billion light years farther the other way.

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