Recent content by Matterwave

If I had an "a-ha" moment for special relativity, it was after learning General Relativity. Specifically chapter 8 in Wald on causal structure. It helps me immensely to think of things in coordinate invariant ways. Thinking in this way, the relativity of simultaneity of SR becomes a consequence...

Yes I would agree. To be clear, what I meant was that the construction I made in post #16 is the idealized / non realistic one. Nevertheless, when we work in the standard SR formalism and give coordinates to events, we don't typically demand that we only patch things together from realistic...

I have no problem teaching this radar-construction method for inertial observer coordinates. I think it gives a very nice illustration of how one could go about trying to construct coordinate systems. However, this method, by definition, can only construct coordinates for events which are...

Semantic question -- when you say "yes it is", you are saying it's trivial to count or it's not trivial to count? I might have phrased my point better as it's not trivial what you count as distinct fields.

I'm going to have to think on this more but it seems highly non-trivial to me to even count the number of fields.

Pretty good starting point, but let's make things a bit sharper. Consider 1. Is it possible to do what you say for any two events? (Hint: it's not, but why not?) 2. What does it mean for two events to happen simultaneously in one frame of reference? 3. In your description of you and your...

What is the reason to count only 6 quarks? We count only the doublet from the weak SU(2) interaction and not the triplet from the strong SU(3) interaction? Naively I would have thought 18 -- 3 generations by SU(2) doublet by SU(3) triplet. And this is not even getting into chirality and spin. 😂...

Maybe we can try another way. Can you say in your own words, without quoting, what "relativity of simultaneity" means? It seems to me that your core confusion is not understanding what the relativity of simultaneity means.

I wonder how he counts 25.

These are not the same moment, there is no universal same moment. That is exactly the point of the relativity of simultaneity. Please see any of our replies above. You have everything you need to answer this question, sometimes you just need to sit and think on it.

Let's try to get clear on what's going on. It's super easy to get a lot of misconceptions and it all has to do with lack of verbal clarity of what the mathematical objects in the theory mean. We first start by defining what a coordinate system even is in SR. A coordinate system for an observer...

So to answer the top level question, yes measurements will affect ##\langle A\rangle## because they affect ##| \psi\rangle## and ##\langle A\rangle=\langle\psi|A| \psi\rangle##.

Others have discussed some practical issues with doing this experiment but if we ignore those, we can analyze this experiment based on the pure mathematical formalism. At least it's relatively easy to do in standard QM, ignoring QFT effects of particle annihilation, creation etc. From that...

This is a very long question which covers quite a bit of the QFT machinery. It might be more productive to focus on one specific question. For example, ultimately why does nature follow ##SU(3)\times SU(2)\times U(1)## symmetry is unknown.

They earn their name "ghost particle" :)