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Jan
26
comment Can matter really fall through an event horizon?
Sounds pretty good to me!
Jan
19
comment Does momentum space have a speed limit?
Good point for consideration, thanks! I gave that one mostly because motion is such a tricky issue in momentum space, and that is one that has meaning. I am... genuinely unsure?... whether such a band drop, which is a quite high energy event (X-ray photon emission for silver) qualifies as a purely quantum event in momentum space, or instead has a kinematic component. I suspect the latter because those high energies which would not be typical of something falling under the auspices of time-energy uncertainty. But in any case, my intent was to give that only as an example, not the defining case.
Jan
18
comment Does momentum space have a speed limit?
Nice point, one that makes me think "I should have thought of that!" (Cool name BTW, apt for this question.) So my question is equivalent to "Is there a maximum acceleration regardless of the magnitude of the force applied?"... which sounds like the situation when approaching $c$... hmm!
Jan
18
asked Does momentum space have a speed limit?
Jan
12
answered visible light spectrum
Jan
5
comment Entangle more than two atoms?
Whoa! Entanglement is not gravity. Entanglement is arguably everywhere. That includes at astronomical distances, e.g. for two photons billions of light years apart after being created by an early electron/positron collision. But if entanglement was gravity, you would expect the strongest gravitational attraction to occur between the lightest, simplest particles, such as those two photons. That's not what we see, since gravity is strongest between the heaviest particles that are least likely to have detectably entangled states. Complex entanglement networks relate to entropy, not gravity.
Jan
5
comment Entangle more than two atoms?
@OlegSilkin yes, experimentally meaningful entanglement — the kind that is both detectable with real equipment and not explainable using speed-of-light constrained casualty — is a lot like a very tiny, rather precious resource that once created cannot be replicated, only divided up or spread around.
Jan
5
comment Entangle more than two atoms?
@igael, correct, it would have been more precise if I had said "entangled states of composite, multi-particle objects".
Jan
5
answered Entangle more than two atoms?
Dec
22
comment What allows us to assume spacetime is flat when no normal matter is present?
Ah, I see you have an answer. Hmm. Try reading his question again. Ask yourself "What is the core issue that is puzzling the writer? Does the writer have some kind of subtle misconception not about the precise mathematical formulation of how curved space works, but perhaps in how we interpret the experimental data gathered by telescopes?"
Dec
22
comment What allows us to assume spacetime is flat when no normal matter is present?
Heh! That's a delightfully odd way to get a minus one! Alas, I'dhave to think hard about how to make it sound more complicated, so I'll just pass... :)
Dec
22
comment Does laser light with less than the work function still ionise some atoms?
Two-photon absorption has even become a lively research and trcnology topic these days. Neural researchers use it to select and activate individual neurons, and if you search the web, you can find amazing micro-sculptures created by using two-photon transitions.
Dec
22
answered What allows us to assume spacetime is flat when no normal matter is present?
Dec
22
answered Is a traveling magnetic field identical to the field of a moving magnet?
Dec
17
comment Why is the charge naming convention wrong?
Frankin was talking about wires, and guessed wrong about which charge type was moving and which type stayed in place.
Nov
14
awarded  Good Question
Nov
11
comment Why is the charge naming convention wrong?
I read the book way, way back in middle school. It was a biography of Franklin. I'll look online, though.
Oct
19
comment Entanglement in time
Nope! There truly is a delightfully simple relationship going on here, which is only those sets of relationships that have left no trace in the web of bits we call "history" or "classical causality" are allowed to be changed in what looks to us (from within that web of bits) like the past. So instead of a change — a real transfer of information that changes the known past and so would create a paradox — all we ever get by entangling with and touching the quantum past is a surprise, a gift of a newly created past from a box that no one anywhere within the classically historical ever opened.
Sep
26
awarded  Good Answer
Sep
24
comment What is entropy really?
I really do think you need to analyze your own example a bit more closely. You can't just mix up and down spin states at molecular levels, even with neutral atoms, without incurring energy redistribution implications. Your specific example of up and down electrons is actually a particularly bad example, since each of the two populations would nominally internally be in full Pauli exclusion due to their shared spins. Allowing them to mix would result in immediate pairing of up and down electrons and a rather considerable release of energy of the same order as a strong chemical bonding reaction.