Recent content by ersmith

@adam_snyder if you have a software development background, and believe you have found some improved ways to do computational general relativity, why don't you contribute to one of the many open source GR programs? A Google search turns up a number of projects on GitHub, and some other projects...

Edited to add... I'll change it in the comment

Putting aside the history for a moment, the significance of universal simultaneity in Newtonian mechanics comes from there being no maximum speed: this makes the causal past expand to fill all of spacetime in the coordinate past. In a universe in which there is a maximum speed this is not the...

It should perhaps be noted that while LET can reproduce all of the predictions of SR, it does not naturally extend to a theory of gravity (general relativity) in the same way that the geometric interpretation of SR does. This is also a significant reason to favor the geometric interpretation.

One more thing to note is that even if we disregard quantum mechanics and treat the neutron star as a collection of classical particles, whether or not adding another particle causes a collapse would depend on the energy of the incoming particle, not just on its rest mass. So even in this...

No, determinism is compatible with presentism and other interpretations as well. Basically determinism and the block universe are independent concepts.

Note that by "determinism" in physics one usually means that the state of the universe at time ##t+1## is a function of its state at time ##t##. The block universe does not imply this kind of determinism and is hence quite compatible with probabilistic or random physics.

Your comments seem to suggest that there's a "true" one way speed of light that we just can't measure. That's not the way it works in relativity. Rather, the one way speed of light is defined by the synchronization convention chosen. Hence it is in a sense arbitrary (although if you want your...

Indeed. After correcting for light travel time, each finds the other's clock to be ticking more slowly. The geometric reason for this is explained in earlier messages, and in particular in Orodruin's insight at https://www.physicsforums.com/insights/geometrical-view-time-dilation-twin-paradox/...

The quoted text concerns me because it seems to express a somewhat muddled view of what a "frame of reference" is. You're correct to say that an event does not have a frame of reference. That's because in special relativity a frame of reference is literally just an assignment of coordinates to...

Remember that the paths objects take are geodesics in *spacetime*, not just space. So the answer to "can't they be stationary" is that objects aren't stationary in time. In some sense they're constantly "moving forward in time"; although probably a better way to think of it is to consider the...

What it amounts to is that he identified the events ##(0, L)## in the Earth frame with ##(0, L')## in the muon frame. These are not the same spacetime events. This is obscured by his poor choice of coordinate systems and muddled notation.

Let's take the origin to be the creation of the muons. Then the detection of the muons has coordinates ##(t', x') = (\frac{L'}{v}, 0)## in the muon frame, and ##(t, x) = (\frac{L}{v}, L)## in the lab frame (using units in which ##c = 1##, and making the positive x axis point from creation to...

The paper basically goes off the rails in one sentence: "The altitude where the muons are created is the initial distance between the origins of the relatively moving frames $K$ and $K'$ at the instant muons are created." There are two fundamental errors here. The phrase "at the instant muons...

The "equations for length contraction" are valid only between points measured at the same time in the moving frame, which is not the case here. The full Lorentz transformation is required.