Recent content by S.Daedalus

OK, there's a bit I don't get, I think. So the final state is: ##|final\rangle = \frac{1}{\sqrt{3}} |\overline{h}\rangle |-\frac{1}{2}\rangle + \frac{1}{\sqrt{3}} |\overline{t}\rangle |\frac{1}{2}\rangle + \frac{1}{\sqrt{3}} |\overline{t}\rangle |-\frac{1}{2}\rangle## Expressed in the...

My main issue with the paper is that I don't understand how it's justified to have the value of z be an element of the story of A, before A has carried out any measurement. To A, and hence (to my understanding), in any story about A's experiment, before they perform a measurement on the system...

Another paper using the same coincidence between the gamma ray signal and the LIGO event by John Ellis et al. claims to constrain the difference between the speed of light and that of gravity to within a factor of ##10^{-17}## (!).

True, but aren't there also theories that change the low energy/long distance behavior of GR? Like TeVeS or Modified Gravity or other attempts to give a relativistic formulation of MOND? I doubt any of these would yield any difference to vanilla GR in LIGO experiments, but if somebody...

Well, the AdS/CFT correspondence as such is probably not directly applicable to our universe: we don't live in an AdS-spacetime. One hope is that there is a more general gauge/gravity or at least dS/CFT correspondence, such that you could extract physics of our 3+1dim gravitational universe from...

There's a somehow related set of issues I find myself pondering time and again: In 1995, Ted Jacobson derived Einstein's equations from thermodynamics across a horizon. Roughly, he showed that if the horizon's entropy is given by the Bekenstein-Hawking formula, then the second law of...

Thanks for your answer, Haelfix. I think this part: is actually the origin of my confusion. I thought that, quite apart from firewalls, etc., when Alice jumped into a black hole, the infalling Hawking radiation ought to be, to her, in a mixed state no matter what, but that seemed to lead to...

So while reading some old threads/blog posts on the black hole firewall paradox, it occurred to me that I had some residual confusion regarding why firewalls (supposedly) form at all. IIUC, the argument is that usually, the vacuum is a highly entangled state, and that disentangling it (in order...

The Horodeckis, hailing from Gdansk, are very well known in quantum information theory; it's a father (Ryszard) and his three sons. Story goes, they used to have discussions on the kitchen door at lunch time, which had been converted into a blackboard... Speaking about father/son teams...

What about the temporal case, do you think there's more than one cat, i.e. different cats at different points in time, as well? Or do you see some principled difference between a temporally extended cat, and one that's extended across different branches of the wave function?

But this isn't even true classically. Consider the wheather: either it rains here, or it doesn't rain here (or there's more than one wheather here, whatever that may mean). But of course, neither of these propositions has any content, they're not capable of truth valuation. What's missing is...

My pleasure! The same thing as it always means: you can't entangle three maximally entangled particles with a fourth one. Generally, if you have some entanglement measure E(A|B), which measures the entanglement of the system across the partition A|B, then, for n+1 parts A,B_1,B_2,\ldots,B_n...

Both! There are two inequivalent ways to entangle three particles, known as the GHZ and W states (this was shown in a famous paper in 2000 with the masterfully descriptive title Three qubits can be entangled in two inequivalent ways). For the GHZ-type states, if you trace out ('throw away')...

What if the guy in the shop scammed you, and gave you three 50g-balls instead of five 30g-ones? How do you find out? If you suspect the fraud, how would you convince a judge?

Incidentally, a somewhat similar way of thinking that I'm not quite as convinced doesn't work comes from taking advantage of the asymptotically de Sitter nature of the universe: while decoherence alone can't ensure the emergence of a proper mixture, maybe as soon as the entangled parts of the...