In this age of (righteous) outrage, for anything that is worth commenting on there exists a non-empty set of someones who enrich the debate with their colour commentary and diversity dialogue. I thought I was being left out of this paradigmatic vanguard of intersectional voices, the last time I wrote on a predominantly white male topic. So, going with the zeitgeist, I present this diabolical conversation between two well-fed, entitled white males talking in presumptuous tones about the entire universe and laws that, they say, affect brown people too. Heck, brown and black… and green ones too! Weird superpositions (fancy short-hand for white super*im*position) and splitting of our worlds (more Partitions of brown people!) happening to us brown folk that – get this – we are *not* even aware about!

It is also revealed in the conversation that one of them admits to a clear connection with the Zionist entity (ack thoo!). Their designs seem sinister, questioning agency and free-will at one point – the cheek of these white males, I tell you! Indeed, it has all the makings of a plot to deny self-determination to assorted brown bredrin across the globe. I shall have none of this white conspiracy and nor should you. But watch it to know their evil designs on us….

In another branch of the wave-function of the universe/Universe, we are all pasty white men named Everett…

Just read the “predominantly white male topic” linked in this article, but since comment section is closed in that article, using this space to comment.

Firstly, I wonder why do you call your article on QM a white male topic. Most white males I know of will find QM akin to general anesthesia. Anyway, I have a question. How do physicists fire a single photon? I didn’t know that they can even isolate a single photon? What mechanism is used to produce a single photon. Can you elaborate on this?

Personally, I like the Many-Worlds interpretation of wave function collapse better than Copenhagen interpretation. There is something inherently satisfying quality about it. In many-world interpretation India wins all world cups in the alternate universe; both Jai and Viru live; I become a nine-pointer; the possibilities are endless – literally. 🙂

We need more such articles on disparate fields. Also, I will be interested in knowing something about black holes, and especially the popular solutions to resolve their singularity. What is your personal take on the resolution of Black hole singularity?

@Scorpion eater

Did you mean the solutions to the black hole information paradox, or resolutions of the black hole (and/or cosmological) singularity?

Both problems are very much still up in the air, but the information `paradox’ was livened up recently by the so-called `Firewall’ proposal of Almheiri, Marolf, Polchinski and Sully (all at UCSB) — where it was proposed to elevate the black hole event horizon (typically, a benign bounding surface with no particular physical significance for an infalling observer) into a physical surface (a firewall) where the information that would’ve been lost to the final black hole state (an evaporated remnant + pure thermal (Hawking) radiation at infinity) persists as a haze of `virtual particles’. The reason it’s still controversial is that people still disagree on the basic facts. However, if you examine the debate closely, it’s because people have subtly different definitions for physical quantities and have been arguing past each other. Sound familiar?

To brown this story up, as one should around here, the so-called firewall proposal pretty much plagiarizes an earlier idea that went by the name of the Fuzzball proposal, by Samir Mathur at Ohio State University, who proposed that a black hole is really a quantum superposition of geometries, and the event horizon has physical significance and has a local energy density and (Information) entropy associated with it. All the heads in the field know this, btw, but it took him a while to get his due…

If you were referring to resolution of the actual black hole singularity, I could tell you about that too but that’s a whole other story. I’ve written papers on resolving cosmological singularities, but the basic physics is very similar in string theory and so-called `effective field theory’ approaches to gravity.

I meant the mathematical singularity that arises at the center of black holes in the classical general theory of relativity.

General theory of relativity predicts that once a body implodes to a volume smaller than its event horizon, then no known force can prevent it to be crushed down to a point. So the density and the spacetime curvature at this point goes to infinity.

Obviously singularity is just a mathematical concept. Singularity cannot arise in nature. Intuitively it makes sense that a region of spacetime can’t have infinite density. So some resolution of the singularity is necessary for any theory of gravity to be valid. Singularity is basically a problem that cries out for a solution.

Physicists usually say that beyond the boundary of event horizon the laws of physics break down (Which is basically a polite way of saying that they have no clue what the hell happens beyond the event horizon).

There are quantum theories of gravity, but to the best of my knowledge they have not been very successful in resolving this singularity.

There are many speculations about the nature of black hole singularity . Some physicists predicts that they basically open the door to a branch new universe.

“Physicists usually say that beyond the boundary of event horizon the laws of physics break down (Which is basically a polite way of saying that they have no clue what the hell happens beyond the event horizon).”

This is not accurate (see my earlier comment). In general relativity, event horizons are benign surfaces. Unless you believe in the firewall resolution of the information paradox (jury is still very much out on that one), an infalling observer would experience nothing different as they cross a horizon — the only difference is that now they are forever cutoff from an observer at infinity. That’s not such a big deal. We exist in a Universe with multiple observers cutoff from each other by cosmological horizons. You can also create one for yourself in theory: just start accelerating (however gently) in a given direction at a constant rate forever (that’s the tricky part). You’ll now have a distant so called `Rindler horizon’, and spacetime will split into two causally disconnected wedges, just like it is for a Schwarzschild black hole.

“There are quantum theories of gravity, but to the best of my knowledge they have not been very successful in resolving this singularity.”

No-one agrees on exactly how singularities get resolved in a quantum theory of gravity, but almost everyone agrees on approximately how this will happen. There are even many explicit models where you can kinematically (because of the very structure of the theory) or dynamically (because of a particular solution within the theory) resolve spacelike and timelike singuilarities. Too many to list here, but they all involve new degrees of freedom appearing at very short distances — sometimes well before the scale where quantum gravity effects are supposed to kick in.

You’re right in identifying that the singularity is a mathematical fiction resulting from extrapolating your formalism beyond where it’s regime of validity. To illustrate this point in a more familiar context, consider the mundane example of the force between two charged point particles. By the inverse square law, it goes to infinity as their separation between the point charges goes to zero. This bugged the hell out of physicists for decades (the classical self energy of the electron problem) before we invented Quantum Electrodynamics. Now we know that there are no such things as point particles, only probability clouds (wave-functions) smeared out spatially such that no matter how close you bring clouds of two distinct particles together, there is no sense in which their wave-functions are ever in the same `place’, so no infinities of the sort people were worried about before appear. This is not to say this other formalism doesn’t come with it’s own limits, seen as new infinities, but these dealt with in a systematic and self consistent procedure that renders finite observable answers — a process known as renormalization. The theory of `Renormalization’ underpins of all of physics, and is perhaps the most profound insight humans have had into the nature of things since Einstein. In a nutshell it states that you don’t need to care what physics at fundamental scales is or how it manifests, you can consistently parametrize your ignorance in a systematic way, and so long as you ask physical questions, you can as Feynman exhorted, just “shut up and calculate.”

@scorpion eater

I will reply to other bits of the comments later, but this bit caught my eye and needs to be clarified at the outset, because it results from a widespread misconception of what QM is:

This is a false notion. MWI does *not* imply that anything will happen, but all the classical possibilities associated with a given quantum experiment will happen. Note the phrase “classical possibility” and “quantum experiment”.

In other words, you will have to demonstrate superposition (which gets lost very, very quickly) between you getting a CGPA (*) of anywhere between 5 and 10 for all those possibilities to realize. Not everything in this world is a quantum experiment, and only real quantum experiments “split” worlds.

Secondly, if the classical physics does not admit a possibility in a given quantum experiment, then that will not be part of the quantum wave function either. So, one cannot create a quantum experiment in which we escape Earth’s gravity on a flying carpet. So the possibilities are

bounded, not “endless”.(*) Or CPI if you’re from one of the shittier IITs 😉