Timeline for How can the speed of light be a dimensionless constant?
Current License: CC BY-SA 3.0
21 events
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| Dec 12, 2018 at 2:19 | review | Suggested edits | |||
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| Feb 25, 2013 at 16:45 | history | edited | Eduardo Guerras Valera | CC BY-SA 3.0 |
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| Feb 9, 2013 at 16:48 | comment | added | Larry Harson | Just put at the top of your answer: "c is dimensionless because you are assuming that time has dimensions of length and, as an direct result of that, velocities are automatically assumed to be dimensionless". | |
| Feb 9, 2013 at 15:02 | comment | added | Eduardo Guerras Valera | Dear @Larry Harson, I have erased the comment that didn't add much physical information and perhaps might result sort of annoying. But the rest of the comments seem fine to me, since they reinforce what has been said in the main answer to other users that might also have the same doubts as you exposed in your (now erased) comments. However, I think the answer is clear enought as it is and I am not going to add anything more. | |
| Feb 8, 2013 at 21:17 | comment | added | Larry Harson | "c is dimensionless because you are assuming that time has dimensions of length and, as an direct result of that, velocities are automatically assumed to be dimensionless". Well that's more like it, thanks. Now please update your answer to show why we can assume this. Please delete the rest of your comments, and I'll do the same with mine, except this one :) | |
| Feb 7, 2013 at 14:54 | comment | added | Eduardo Guerras Valera | Keeping track of the symbols c, G, Planck constant and so on is a pain in the neck, and it is unnecesary. It distracts you from the essentials and obscures the meaning of the equations by loading them unnecesarily... Paying attention to covariant/contravariant indexes and all that stuff demands a lot of atention and is very prone to error, and thus every convention that simplifies your life is a great thing. After you spend some afternoons re-doing a couple of proofs and derivations in GR, believe me you will completely agree with calling your own mother dimensionless if necessary... | |
| Feb 7, 2013 at 13:34 | history | edited | Eduardo Guerras Valera | CC BY-SA 3.0 |
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| Feb 4, 2013 at 21:04 | comment | added | Eduardo Guerras Valera | @Neo,as I said in the last comment, please google for "metric signature," and then you will understand. Or post a new question linking to this one (perhaps "Why the metric in that post has what it seems to me the wrong sign?"), I am sure many users will answer. Good luck! | |
| Feb 4, 2013 at 20:18 | comment | added | Neo | @Eduardo ds is (-,+,+,+) but where the $icdt=dw$ then ds is (+,+,+,+) | |
| Feb 4, 2013 at 19:21 | comment | added | Eduardo Guerras Valera | @Neo, no my friend, it isn't. Google for "metric signature". Relativists prefer usually (-+++) as Einstein in his lectures, and particle physicists (+---) although it is not a general rule and it is only a matter of taste. Minkowski wanted (++++) and so he had to define $x^0=ict$, so that $(x^0)^2=-c^2 t^2$ | |
| Feb 4, 2013 at 10:18 | comment | added | Neo | @Eduardo Your equation is wrong: $ds^2=-c^2d\tau^2=-(c^2dt^2-dx^2-dy^2-dz^2)$ | |
| Feb 3, 2013 at 22:38 | history | edited | Eduardo Guerras Valera | CC BY-SA 3.0 |
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| Feb 3, 2013 at 21:08 | history | edited | Eduardo Guerras Valera | CC BY-SA 3.0 |
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| Feb 3, 2013 at 20:28 | history | edited | Eduardo Guerras Valera | CC BY-SA 3.0 |
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| Feb 3, 2013 at 19:56 | history | edited | Eduardo Guerras Valera | CC BY-SA 3.0 |
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| Feb 3, 2013 at 19:48 | history | edited | Eduardo Guerras Valera | CC BY-SA 3.0 |
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| Feb 3, 2013 at 19:18 | history | edited | Eduardo Guerras Valera | CC BY-SA 3.0 |
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| Feb 3, 2013 at 19:15 | comment | added | Eduardo Guerras Valera | Schutz is not wrong, please read the post. And his book is probably the best one to start studying GR seriously. | |
| Feb 3, 2013 at 19:10 | history | edited | Eduardo Guerras Valera | CC BY-SA 3.0 |
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| Feb 3, 2013 at 19:05 | comment | added | Physiks lover | You should be more explicit in your conclusion then: c is not dimensionless and so Schultz is wrong. | |
| Feb 3, 2013 at 18:53 | history | answered | Eduardo Guerras Valera | CC BY-SA 3.0 |