Recent content by Oudeis Eimi

I'm a hobbyist synthesist. That is, my main instrument is the synthesiser, meant not as a poor substitute of 'keyboard' sounds nor as a preset machine, but as an instrument capable of moulding or shaping sound. I use both hardware instruments and sound synthesis software. Since in practice the...

It doesn't need to "return" to it. Whatever its state after the observation, it will be a superposition in some base.

As others have mentioned... no, it's not "true" (it's not what QM says), but more importantly, "observe" in QM doesn't mean what you think it means. More to the point, something macroscopic (say, our very own Moon, but this would also apply to a speck of dust... or even to many things...

Welcome to Physics Forums! Your question isn't very clear. Could you describe the gravity problem you're referring to?

This is a good question, and the most straightforward answer I can give is "I don't really know" :-) However, allowing for something less straightforward: instant forces at a distance, as they are used in Newtonian mechanics, must comply to the known conservation laws for linear and angular...

I don't think we can do that, not in a relativistic analysis anyway (which is required for electrodynamics). Since covariance (in classical theories at least) implies locality, the field must be regarded as the basic object, and (classical) point particles taken as a limiting case of a very...

Not if you take into consideration the angular momentum of the field itself :-)

The OP has many misconceptions. Pressure as force times area? Temperature as mass times "internal heat" (whatever that is)? Homogeneous pressure in a self-gravitating cloud? Besides, how many particles are you simulating, OP? Unless you have a lot, temperature and pressure aren't going to be...

Hello OP, the above makes IMHO a good example of your present confusion on this subject. I'll try to clarify some things here: Outcomes, for the simplest, ideal case of a "projective measurement", are eigenvalues of observable operators (I'm restricting discussion to discrete spectra here for...

Ballentine is indeed an invaluable reference. Yes, I was restricting the discussion to pure states, so as not to further confuse the OP, but the distinction is always worth making indeed.

It does not justify the statement, because that statement is not correct. The state is unique up to a phase factor, a particle is never in two different states (from two different rays in the Hilbert space anyway). Using the example of a spin 1/2 system, a state | z up > can be expressed as a...

That's not what superposition means. Other posters have expressed doubts that you understand what a vector space is, and that understanding happens to be critical to this issue. ANY state vector (that's the simplest kind of quantum state) is in an infinite number of different superpositions...

Thanks again Bill. I have NR QM at the level of Cohen-Tanoudji (plus a smattering of QFT which is probably of little use here), so I will get the book. Thanks also for the link, I will study it.

Ahhh yes, of course. However, is the environmental monitoring equivalent to an ideal measurement? I would say (but might very well be flat wrong) that it's more like a simultaneous, *imperfect* measurement of both position and momentum (to within HUP restrictions obviously). What do you think?

Thanks Bill. I knew that book (considered it for someone else in fact), but never read it myself. My level is a Physics MSc, but my specialty is Materials Science, not open quantum systems. That's why I don't (yet) have Schlosshauer's book, which I have been told is the book to get on...