Well the band wagon has turned 180, now it’s fashionable to point out the flaws. My issue with this kind of videos is really, where are you in the early days of the hype, when the public needed cautions the most? A convenient naysayer when all the actual hard works have been done elsewhere

Documentation is different from demonstration. Text (with graph or animation interspersed to unpack unintuitive terms) wins for documentation. Video could be good for demo if presented in a no-nonsense manner.

Hiw stable is this kind of density? Is it going to shrink over time?

Well, even the picture is in the picture…

What other fields?

One idea that captures my imagination is the concept of cyclic inflation – a framework that combines cosmic inflation with the notion of cyclic collapse and expansion, or bounces.

This captivating idea, conceived by former postdoctoral researcher Dr Tirthabir Biswas and myself, suggests that the Universe undergoes infinite cycles of collapse and expansion.

Here’s a link to the good professor’s paper for those interested. As others have already pointed out, cyclic universe as an idea is not new – the paper itself cited refs 11-19 as prior art, the oldest of which dated back to 1931.

The claim the good professor is trying to make is somewhat subtle for any lay person skimming through the article: the novelty of their idea is not cyclicity itself, but rather to combine cyclicity and inflation. To be honest, as a lay person I would have thought a cycle would consist of an inflationary period and a deflationary period, so forgive me for not seeing the point! The following technical statement from the paper perhaps makes more sense:

Thus although cyclic and inflationary models are not mutually exclusive, it is natural to try to attempt to replace inflation altogether with “cyclicity”. In this paper, however, we take a slightly different approach, by exploring whether by embedding inflation in a cyclic universe setting, some of it’s problems viz. (i-iv) can be alleviated. Our main idea is to merge inflation with cyclic cosmology where the universe undergoes an infinite number of cycles before bouncing into a final power-law inflationary phase.

I think the better way to say this is that not only do you get inflation (and deflation) for free within each cycle, but the sequence of cycles is itself inflating – a larger scale inflation modulated by a smaller scale periodic function if you will.

The question now is, of course, is there a “first cycle”, and what happened before it. Why stop there and not have some meta-cycles? That would bring the whole business to a full circle.

The point is there are established conventions among the practitioners on how these are pronounced, and not getting them right says something about the youtuber who may otherwise appear as an expert.

You might be right on how the name ‘Schrieffer’ should be pronounced in its original tongue, but I’ve heard multiple former students and colleagues of Bob Schrieffer pronounce it otherwise to conclude that theirs is probably how Schrieffer himself intended his name to be pronounced.

Yeah, can’t wait to hear economists’ take, or The Economist’s…

Hi Joe Brian

Not to be snobbish or anything, but at this juncture I wouldn’t trust anyone who can’t pronounce arXiv (or Schrieffer for that matter) correctly to explain room temperature superconductivity to me. Hell I barely believe anyone with a materials/physics degree…

I’m not an astrophysicist nor a relativity theorist, but this makes absolutely no sense… The article writes,

When we say that the Earth is 4.5 billion years old, technically we mean 4.5 billion years is the maximum amount of relative time any thing could have experienced since the Earth was formed.

If by “Earth is 4.5 billion years old” it means the time lapse as experienced on earth – in other words, as measured by a clock on earth, then the clock is in the rest frame and therefore measures the shortest possible time duration among all clocks in other (moving) inertial frames, not “the maximum amount of relative time” (special relativity). I think the author is confusing this with the twin paradox where the traveling twin ages slower. The talk of

There is a maximum amount of relative time that can be experienced between any two points in time (no time dilation). There is a maximum relative distance between any two points in space (no length contraction)

is also troublesome – what is even “two points in time (no time dilation)”? One should instead be talking about two events and their space-time coordinates

In general you’ll be happier if less fxxk is given to someone else’s opinion. I’m not sure how important “someone else” being a parent is, other then maybe the correlation with the time spent with them or the survival resources they had control over, etc.

How else can you generate a micro blackhole for space jump???

The “state” in “most likely state” refers to a macro state, which in the “packets of energy” example is specified by the pair (left total energy, right total energy). A macro state with more microscopic realizations (hence more likely – all microstates of the same energy being equally likely) has higher entropy by definition. The video could perhaps make the distinction between micro- and macro-states more clear, but doesn’t seem like a misconception