PeterDonis's latest activity

Here, I'll give you the correct answer to this question: 1.77 years. I got it by a simple Lorentz transformation, with ##v = 0.8##...

Unfortunately, Brian Greene is notorious for only giving you part of the story. His pop science books and TV shows are even worse. I...

Maybe this is jumping ahead... but I think the quicker you get to this topic (below), the better off you'll be. Have you tried to draw...

No, she does not know that. What she knows is that Earth and Proxima Centauri are 4.25 light years away in the frame in which Earth and...

Suppose I prepare a large number of particles in the same state (i.e., same wave function), and then I measure the momentum of each one...

Yes, but we can still use them mathematically to help understand how actual physically realizable states like wave packets work. This...

That product is what appears in the quantum uncertainty principle. But each ##\Delta## by itself is not constrained by that principle...

This intuitive picture works nicely for position and momentum. But the uncertainty principle is not limited to position and momentum. It...

I'm not sure what you mean by this. As has already been pointed out, the uncertainty principle does not constrain the variance of...

Statistical uncertainty, which is not the same as the "uncertainty" part of the uncertainty principle. I'm not sure the OP grasps that...

That was not at all clear, and the OP question is about the uncertainty principle.

This has nothing to do with the uncertainty principle, because we are not looking at the probabilities of results of future measurements...

Mathematically, the uncertainty principle sets a lower limit on the product of the variance in position and the variance in momentum...

"Uncertainty" as in the uncertainty principle is not even about the variance of a large number of measurements of a single observable...

Note that we don't have light sources that allow us to control when a photon is emitted. The best we can do is to turn down the...