Recent content by Peter Martin

IBIX, Thanks for the feedback. Obviously, you've had more exposure to various versions of this experiment than I have. But isn't it critical whether the lightning strikes occur in the train's reference frame or the embankment observer's? It seems to me that in whichever case the observer in that...

The popular account of Einstein's train-and-lightening thought experiment doesn't demonstrate "the relativity of simultaneity" as it is always claimed. In fact, it does the opposite: By describing the embankment observer as "at rest" relative to the strike locations and the train passenger as...

It seems to me that Einstein is inadvertently claiming absolute motion and absolute rest when he states that the train observer sees the strikes sequentially while the ground observer sees them as simultaneous. Since there's no acceleration, we are free to reverse the roles and consider the...

Janus, I can't thank you enough for your time and effort to explain the train-lightening experiment to me. I'm still processing your reply, so I'll thank you properly when I finish. I believe your explanation is the first time anyone on PF has introduced length contraction into their explanation...

In your reply you state, "The point is that when you set up the experiment, you choose in which frame the flashes are simultaneous." So please answer my question in this scenario. You are Zeus, the god of thunder and lightening. You can cause a bolt of lightning simply by pointing a finger at a...

Love it!

I agree that she can calculate the train's speed only relative to the ground. But considering the train "at rest" and the ground "speeding past", tell me how the ground's speed can affect how light behaves in the in the train. If you were in a basement laboratory and did the experiment with the...

I agree. Here's my thought on the subject of inertial frames of reference and the principles describing the propagation of light. Does Einstein’s train-lightening thought experiment violate SR? Let’s propose a scenario which doesn’t differ significantly from Einsetin’s. A high-speed bullet...

The reader is misled when the strikes are described as "simultaneous". They are simultaneous only from the man's point of view. Because she is moving forward, for her to see them as simultaneous, the rear strike would have to occur first because it has a longer distance to cover before reaching...

I've pondered this thought experiment for years and think I've arrived at the simplest explanation. The reader is tricked by the description of the two strikes as simultaneous ("at the same time" as you put it). But that's only from the man's point of view. Let's re-describe the situation. The...

The answer can be explained without any reference to Special Relativity, Einstein, or inertial reference frames. Ask: How could the two lightning strikes occur so that the woman on the train sees them as simultaneous? We can assume a conventional view of reality: that the landscape is "at rest"...

The problem is in the description of the situation, which states that the lightning strikes are "simultaneous" without stating that the simultaneity is from the man's (bystander's) point of view. Let's re-describe the problem from the woman's (passenger's) point of view. A woman sits at the...

I thank everyone for their input to my query on the twins paradox. As for length contraction shortening the distance to the target star (not galaxy, thank you ibix) while in inertial motion the space twin can detect neither time dilation nor length contraction aboard his spacecraft . So for...

Does the “space twin” benefit from length contraction as well as time dilation? In Einstein’s thought experiment, let one of twins travel to a galaxy known to be 10 light years from Earth at a speed of sixty percent of light speed (0.6c). Were it not for time dilation the one-way trip would...

Here’s my attempt at answering taenyfan’s very fine question on Einstein’s train experiment: The problem defines two frames of reference moving with respect to one another. In the platform observer’s frame the two strikes are simultaneous. In this scenario the woman must be considered to be...