Timeline for Why can't we find a true inertial frame?
Current License: CC BY-SA 3.0
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| Aug 28, 2015 at 12:30 | answer | added | user56903 | timeline score: 1 | |
| Aug 28, 2015 at 9:45 | history | edited | YiFei | CC BY-SA 3.0 |
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| Aug 18, 2015 at 20:55 | comment | added | Jim | The equations are fine, it's just the most accepted model that assumes the CMB is comoving. It's valid to say it might not be, there's simply no reason to assume that it would have some peculiar velocity and so we don't. If it does, that won't change the physics, just the estimates. It would also give us a new question to try to answer. And it would, amusingly, confuse practically everyone for the first little while. | |
| Aug 18, 2015 at 20:53 | comment | added | Jim | @kasperd .... Age is a tricky thing. It's valid in the comoving frame, which is the one where the CMB has no peculiar velocity, but it isn't valid in other frames already. Not only that, but local perturbations can distort the age of various small regions of the universe. In cosmology, age is a vague term. We'd definitely be able to find a way to define it such that our calculations are fine. But yes, there may be some change in the number itself. | |
| Aug 18, 2015 at 20:44 | comment | added | kasperd | @Jim Wouldn't all calculations of the age of the universe be invalidated if the CMBR reference frame wasn't at rest? | |
| Aug 18, 2015 at 13:59 | comment | added | Jim | @kasperd key word there being "appear". The CMBR is a great reference frame, but there's nothing that says it is an absolute rest frame. We can't tell if it is truly at rest or if the entire CMB has some sort of overall peculiar velocity. That said, I agree that it's a more natural frame to use as a basis for an "absolute" rest. Best we've found yet, at least | |
| Aug 12, 2015 at 7:54 | comment | added | kasperd | @Jimself The CMBR does appear to provide a preferred inertial frame. | |
| Aug 12, 2015 at 4:00 | history | edited | YiFei | CC BY-SA 3.0 |
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| Aug 11, 2015 at 22:54 | history | edited | YiFei | CC BY-SA 3.0 |
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| Aug 11, 2015 at 16:04 | history | edited | YiFei | CC BY-SA 3.0 |
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| Aug 11, 2015 at 15:51 | comment | added | Jim | Yes, of course such a frame exists | |
| Aug 11, 2015 at 15:44 | comment | added | YiFei | A frame with constant velocity can be regarded as a reference frame, while respect to it, we define the 0 relative velocity, but this is not necessary. So in this way, I mean a frame with absolutely zero acceleration. Newton 1st law hold in some non-rest frames. But does really a frame with absolutely zero acceleration exist? | |
| Aug 11, 2015 at 15:41 | comment | added | Jim | There's an important distinction. A frame with absolutely zero acceleration exists. A frame defining the absolute rest velocity doesn't exist | |
| Aug 11, 2015 at 15:29 | answer | added | Daniel Goldfarb | timeline score: 2 | |
| Aug 11, 2015 at 15:25 | comment | added | YiFei | Ah, I think the defined frame should consistent with all observations, so i don't really distinguish the two you mentioned | |
| Aug 11, 2015 at 15:25 | review | Close votes | |||
| Aug 15, 2015 at 7:42 | |||||
| Aug 11, 2015 at 15:22 | answer | added | Dhritiman Banerjee | timeline score: 0 | |
| Aug 11, 2015 at 15:19 | comment | added | Jim | do you mean "a frame not experiencing any accelerations whatsoever", or "a frame that defines some absolute rest"? | |
| Aug 11, 2015 at 15:16 | comment | added | YiFei | @Shing Yes, it's consistent. I just think because how much the ball turns describes how good the approximations are, we can finally theoretically find the Newtonian inertial frame | |
| Aug 11, 2015 at 15:14 | comment | added | Shing | Actually, Newton defined inertial frame quite well in his 1st law. What exactly meant by "true inertial frame"? | |
| Aug 11, 2015 at 15:12 | comment | added | YiFei | @Shing Though it's figurative as i understood, that's the true inertial frame while the earth or the sun are our approximations. | |
| Aug 11, 2015 at 15:09 | comment | added | Shing | Define absolute inertial frame. | |
| Aug 11, 2015 at 15:07 | history | edited | YiFei | CC BY-SA 3.0 |
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| Aug 11, 2015 at 14:58 | comment | added | Jim | What are you asking? What exactly is an absolute inertial frame? | |
| Aug 11, 2015 at 14:56 | history | asked | YiFei | CC BY-SA 3.0 |