# Speed of Light

Discussion in 'Physics & Math' started by Willem, May 27, 2019.

1. ### WillemBannedBanned

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What does it mean to say an object travels at the speed of light through time?

3. ### sweetpeaValued Senior Member

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Where does it say that?

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5. ### NotEinsteinValued Senior Member

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Typically, what is meant is that a stationary (in space) object still has a '4D'-velocity through spacetime: it's travelling 1 second per second.

7. ### sweetpeaValued Senior Member

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So, does that mean if the object ''moves'' it will be travelling ''slower'' in time? so to speak? Are we talking of rate of ageing?

8. ### NotEinsteinValued Senior Member

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See, that's why I formulated it so vague: I remember hearing about this, but I don't remember any of the details involved. Hence my request for a source from Willem too.

9. ### sweetpeaValued Senior Member

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I just had a look into a Brian Greene book.
But in the end it all relative, hence the twins. One stays at home the other goes on a rocket ride.

Last edited: May 27, 2019
10. ### exchemistValued Senior Member

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It means one is speaking of something that cannot take place.

11. ### WillemBannedBanned

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One second per second is a dimensionless number (s/s =1).

12. ### NotEinsteinValued Senior Member

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That is correct. So?

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No shit!

14. ### Michael 345New year. PRESENT is 72 years oldlValued Senior Member

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The same same as 1 foot length is 1 foot length

Circular and nonsensical

We (scientists)* have determined the speed of light exact value is 299,792,458 metres per second

And since we have also determined the second to be

the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom

and the metre to be

the metre is defined as the length of the path travelled by light in a vacuum

we come full circle with 3 definitions defining each other

* colloquial I am not a scientists

The only one of the 3 is detectable - the radiation and exist in and of itself

There is no second out there waiting to be found
Likewise no metre floating about for a scientists to grab hold of and claim

They are non existent, except as CONCEPTS

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16. ### WillemBannedBanned

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Then you could say that the object travels at speed 1 through time - odd and inconsistant.

17. ### DaveC426913Valued Senior Member

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That's because it's a ratio.

My scale models are 1/4 inch per foot - or 1/48 scale (no unit).

You would not really say your object is travelling at speed 1, any more than I would say my models are scaled at 48.

You would say your object travels at a ratio of 1:1 with the passage of time.

Last edited: May 29, 2019
18. ### NotEinsteinValued Senior Member

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Ah, so that's where I got it from. I guess my username is very apt.

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19. ### NotEinsteinValued Senior Member

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Tell me then: what is the speed-in-time of a properly functioning clock when you are in the same frame as said clock?

20. ### WillemBannedBanned

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A fool can say speed-in-time = 1.

If it's not foolproof then there is an inconsistency.

21. ### NotEinsteinValued Senior Member

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But didn't you yourself say that in post #8 and #13?

However, it being possible to be uttered by a fool doesn't mean it's wrong, so I don't understand what your point is.

Please point out the inconsistency then.

Also, I notice you've dodged my question, even though you quoted it. Can you please stop being intellectually dishonest for just a moment, and answer the question?

22. ### WillemBannedBanned

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Speed-in-time = -c.t_B/t_B = -c m/s.

Last edited: May 29, 2019
23. ### NotEinsteinValued Senior Member

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What is "t"? What is "t_B"?

But I see you've now answered your own OP. You've derived speed = c, which is exactly what you were asking about, so now you know what it means. I'm glad to have helped you figure it out!