reply on: Why physicists now question the fate of the Universe \ stacker news ~science

247 sats \ 6 replies \ @south_korea_ln 23 May \ on: Why physicists now question the fate of the Universe science

Perhaps dark energy isn’t truly a constant, after all. Perhaps it is something that changes and evolves with time. If so, our cosmic fate could dramatically differ from what we typically suppose. If dark energy strengthens and becomes more negative with time, it could lead to a Big Rip. If it weakens and becomes more positive, it could potentially stop the Universe from accelerating and may even revive the possibility that we’ll recollapse and end in a Big Crunch. With years of new DESI data just waiting to be analyzed, and tens of millions of objects to be added to their upcoming catalogs, we might see what comes of these hints sooner rather than later. In the meantime, it’s of paramount importance that we keep our minds open to all of the possibilities that the data still admits. After all, the Universe may turn out to be a stranger place than anyone has imagined so far.

I'm old enough to have had a teacher in high school believing in the Big Crunch (he even believed in the yoyo universe: expansion, contraction, expansion, contraction,...). Now for years, I told people the consensus is that it's expanding. It's really exciting to see that after all, things might be different again, and a big Crunch is back on the table :)

0 sats \ 4 replies \ @didiplaywell 23 May

I'm adamant on thermal death. Thermodynamics have yet to fail me.

10 sats \ 1 reply \ @south_korea_ln 23 May

Yes, heat death seems to make the most intuitive sense to me too.

Didn't really understand the argument Sabine Hossenfelder made in a video where she explains why she does not believe in the 2nd law of thermodynamics. It's a bit philosophical (and quite out of character as she likes to sh*t on the usefulness or lack thereof of fundamental particle physics research).

100 sats \ 0 replies \ @didiplaywell 23 May

Thank you for pointing me to the video and the right minute where she goes to the point. Seeing that a classic enthusiastic holdish physics teacher haves 1.5M subscribers and her video on such a niche yet fundamental topic haves 1.1 views gives me years of life.

I fully agree with her, that's exactly the way I see it. "Thermal death" is the point where such new complex systems will emerge, and for every new system entropy "starts at zero" in the exact same physical sense and rigour in that every time a column of water decreases, that new level is the new "zero". I have that coupled as part of the reasoning (together with some other stuff I'm working on) that haves lead to the image I posted in my bio:

0 sats \ 1 reply \ @kilianbuhn 23 May

Thermodynamics have yet to fail me.

What do you think lies beyond the universe? What is "nothing" but a different "nothing" than the vacuum of space? And why is this nothing attracting space into it?

Does this nothing adhere to thermodynamics? Isn't the pure exsistence of the something expanding into the nothing kinda not thermodynamics like?

107 sats \ 0 replies \ @didiplaywell 23 May

Interesting questions! :)

To start, there is nothing such as "attractions", a term which is used within physics only in an informal manner. All forces, even field forces, are "pushing". That's exactly the way "suction" works with air vacuums for example. They don't exert "suction", but push material with their blades to another place, so to generate a void that the atmosphere itself fills due to it's own pressure (entropy!). This is no different from the forces you can exert yourself: think about it, you can only push things, never "attract" them.

So, in your words, "nothing can't attract nothing", which holds true regardless of the many interpretations of the words.

Absolutely everything, even nothing, adheres to the fundamental laws of thermodynamics, an absolute power of our knowledge that never stops to amaze me, which secretly relies in the fact that the laws of thermodynamics can't be defined in an absolute form but are always interpreted for every specific context.

0 sats \ 0 replies \ @sefiro OP 23 May

Yeah, I'm also excited that a Big Crunch is back on the table. Personally, I always liked the idea of a yo-yo universe rather than an ever-expanding one, and I still do.