Thread: The speed of light is the same for all frame of reference

1. Why is that so?

let say i am in a spaceship, traveling at 80% the speed of light. Next to me is a ray of light. Common sense tell me that if i measure the speed of the light ray, it would be 20% the speed of light. That is not the case according to the postulate. Can someone tell me why this postulate is ture?

2.

3. Unfortunately light does not have any common sense, you need to take time dilation into account, so if you google 'Time Dilation' you will find many descriptions hopefully at least one will be to your taste.

We measure the 'speed' of something by how far it travels in a given amount of time, light moves at 300,000,000 metres/second

My simple understanding...
Basically when you measure it, your clock will be running about 5 times slower than normal(normal meaning as if you were stationary), so if you measure how far it travels in one of your seconds it will actually be 5 'real or stationary' seconds, hence at the 20% speed (difference)you will see it travel 5*20% - 100% of it's normal distance.

Of course anybody on the ground watching will see it moving 20% faster than you...

Welcome to the forum.

4. if we move in a speed of ight, everything around would still be moving in a speed of light. Not at all. the postulate is a law that is written in the fabric of existence within this universe. It is nature and nature alone that does this crazy things, and we know it only throught experiment, and observation. That is what is presented in my book, a "postulate". This postulate/"law of nature" is the work of nature, and not einstein. My question :why do nature do this. Can we explain this in terms of something more fundemental, more intuitive?

5. I do not understand and therefore cannot answer your previous post. You appear to be wanting a classical physics answer for a question involving relativity.

Originally Posted by isomorphic
This postulate/"law of nature" is the work of nature, and not einstein. My question is to nature itself. why do nature do this.
I'm not sure she's going to answer, but I'll watch eagerly...

6. Originally Posted by Megabrain
I do not understand and therefore cannot answer your previous post. You appear to be wanting a classical physics answer for a question involving relativity.

Originally Posted by isomorphic
This postulate/"law of nature" is the work of nature, and not einstein. My question is to nature itself. why do nature do this.
I'm not sure she's going to answer, but I'll watch eagerly...
I also ask if there was a deeper explanation following that sentence

7. Well, I cannot answer for a deeper meaning, my understang is simply that is is one of the laws of nature we find ourselves bound by in the universe in which we exist. Further research may shed some more light on it or we may have to just accept it as fact.

8. Hi guys. Special Relativity can be expressed pretty simply. Imagine yourself as a metronome. Each tick is a thought in your head, a beat of your heart. If you're travelling with a forward motion of c you can't tick, because any transverse motion would cause c to be exceeded. So no time passes for you. If however your forward velocity is zero you can tick as much as you like, with a transverse motion of up to c. Your time experience is now very different, because it simply depends on how your overall motion is divvied up.

9. i can accept that a 20% difference between your ship and light is compensated back to apparent 100% due the whole scenario slowed down.

but Farsight, you rekindled this old question ive had since childhood ---
within the black vacuum of the space medium, can there be such a thing as perfectly zero velocity or is velocity entirely relative?

IF perfect zero velocity is somehow fundamentally real,
then what does this do to our perception of time? the solarsystem and galaxy is moving us, therefore we perceive time as whatever reasonable speed into which we were born -- but if increased speed slows our passage of time, then would universal zero velocity instantly jump us through all of time infinitely fast? i can almost imagine the whole universe around me instantly warping to its death - or perhaps collapses and big bangs repeating like a humming bird, generating a signature pitch vibration

lets hope the universe is in the key of C

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