# Tag Info

Accepted

### Speed of light postulate in special relativity in inertial vs. non-inertial frames

what is that has brought Einstein to conclude that the speed of light is constant only for inertial reference frames and not for non inertial ones? We know that non-inertial frames violate the first ...

The formula is a special case for a velocity and a boost along the same axis. All variables are scalars (or components along that axis). The most elegant way to generalize it is to use the four-...

### Are objects in an uniform field inertial?

Now, suppose that there is a uniform field that accelerates any particles with constant acceleration. Like gravity, a free object in this field will not be able to detect that it is accelerating, ...
Accepted

### Does the magnetic field, circulating the moving uniformly charged sphere, exert force/tension on it? If so, how is it interpreted in the charge frame?

Yes test charges on the surface of the moving charged sphere feel this force. Yes it affects the strain of the sphere of charge in the lab frame. But don't forget that some external forces are needed ...

### Does Special Relativity require a "ruler postulate" analogous to the "clock postulate"?

Barring its mathematical statement, the clock postulate, in my view, has a crucial physical content: it assumes the existence of ideal clocks whose behaviour is not influenced by their accelerations. ...

The elapsed property time over a worldline is: $$\Delta\tau = \int_W\frac{dt}{\gamma(t)}$$ where gamma is computed in the initial rest frame. Since the two $W$ are related by reflection, they will ...
1 vote

Your question includes an incorrect assumption. If Alice and Bob start in the same place with synchronised clocks, and return to the same place having undergone symmetric journeys in opposite ...
1 vote

### What did Einstein mean in his 1905 paper when exposing the relativity of simultaneity?

Einstein gives us the reverse view of what is usually adopted in modern presentations of SR. Today we would normally consider clocks that are always synchronised in their rest frame, so that when you ...
1 vote

### What did Einstein mean in his 1905 paper when exposing the relativity of simultaneity?

When he's saying that simultaneity is relative, he's saying that the speed $v = ∞$ is not absolute, but relative. In Newtonian physics, it's absolute. Infinity is the speed at which simultaneous ...
1 vote

### Would an object moving close to the speed of light appear colder to a stationary observer?

But this doesn't seem to be right, since the properties electromagnetic waves should be the same in both reference frames. You are right about everything. Except for that quote. So that must be the ...
1 vote
Accepted

### "Rear clock ahead" effect in special relativity

It really useful to consider events, and the difference between them, when considering relativistic effects. So start with a decent space-time diagram from the internet (or draw your own): Then: ...
1 vote

### Lorentz Transformation of Wave Equation

$v$ in the transformation equations is the relative velocity between the frames of reference.
1 vote
Accepted

### Homogeneity of space doubts

Set up an experiment. Find the result. Move the experiment somewhere else and run it again. You will get the same result. To do this, you must move all the important parts of the experiment. For ...
1 vote

### Mach's principle

Mach's principle is an empirical result whose relationship to more abstract ideas is debated but appears to be physically untestable. Using distant matter to experimentally establish inertial frames ...

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