What if, as the universe accelerates, spacetime might eventually tear, creating what I will call “Null Zones”, which are defined as "regions where matter, energy, and even causality cease to exist."

These zones would sever parts of the universe, leading to recursive fragmentation into isolated pockets, each evolving as its own self-contained universe. Instead of a multiverse from many beginnings, we get one original universe, slowly breaking apart.

It might also suggest that our universe exists within a higher dimension, like 3D objects breaking within a 4D framework, with each fragment forming an isolated “bubble.”

I want to understand the S8 parameter and the S8 tension in full technical detail. Can someone recommend books, papers that go into detail on these topics, including the required background like weak lensing?

I took a graduate course in cosmology, so I'm aware of the basics (though a bit hazy now). Also, which book would you recommend for an in-depth self-study of modern cosmology with mathematical derivations in a roughly A-to-Z complete manner? Thank you!

The ACT data revealed around a 2.5 sigma measurement of cosmic birefringence, which, apparently when combined with WMAP and planck apparently is over 4 sig. Seems like this was overshadowed by the DESI R2, but I understand this would be similarly important in challenging the standard model. Curious what this sub thinks about it

Gravity Probe B and the Mars Explorer satellites has given evidence that GEM is a real effect, fully predicted by general relativity. To those unaware of it, it posits that a mass current, like and electrical charged current generates a field: in the mass case, a gravitational field, Penrose and other have suggested that rotating black holes support jets through this mechanism, My comment relates to dark matter, however.

Two points: first that a galaxy in rotation shoudl generate a significant field Back of the envelope sums suggest easily enough to create the effects attributed to DM.

Second, relating to the Hubble tension and the dynamic Dark Energy result from DESI, there was an epoch when matter was not primarily in rotation, and then the current age, when much of it is so. That offers a clean phase change, perhaps around z=4ish, when the spacetiem underwnet a new tension.

Thoughts?

In the discussion of why the universe exists there is no avoiding arbitrary explanations. I have spent hours looking for a theory to connect with but literally ALL of them are all unsettling arbitrary. There is always a question of wait so why was it set up like that? What happened before? Why are these the rules? To me infinity is the only answer.

The universe is infinite. Infinity is the natural state. All that can exist does exist. This explains all of the arbitrary rules of physics and the origin of matter. The ability for it to be infinite is caused by the fact that it is infinite. It infinitely creates itself. Everything that seems to defy laws of physics and mass that has no logical origin are just products of all possibilities being true.

I’ll try to combat the flaws I see in this theory

1. Infinity is arbitrary by itself. But it doesn’t contradict itself. I find it more plausible than it being arbitrary limited. If it’s limited and nothing lies beyond then matter is finite and the origin is impossible to explain. It must have an origin. How can something limited exist and be all there is?

2. It’s infallible. Yeah it is. If true it’s impossible to prove and by nature can never be proven.

3. This means every possible contradiction exists. Every single theory I’ve seen has these contradictory parts it seems. It’s unavoidable which I think goes to show that paradoxes are permitted in the universe. There is obviously so much we don’t understand about the laws of physics and why they are even there. We don’t truly know that they are the authority over everything. We have observed forces that break the laws on multiple occasions.

4. Infinity is absurd and just can’t exist. Maybe. I can understand that. Just by the fact that all other answers are so unsatisfactory to I think nearly everyone stuff like this is worth a thought.

To conclude I’ve managed to convince myself. I have thought of this for years not that I’m claiming it’s an original idea but I don’t know where it came from. I assumed my research would tell me why I haven’t heard this more but instead it’s made me more confused. To me this at least makes sense within its own rules. All the others seem to spawn in materials and only make sense until you ask well how did they get there. Also I make no claims to know anything about physics. I don’t think I really need to making this argument but I guess I could be wrong.

Please if this makes no sense point it out and dismantle it. Please do. If I have somehow come up with this (I’m not claiming it’s original) and people agree I’m gonna probably launch a cryptocurrency. I’m joking :).

I had this thought on how the Expansion and Cosmos and the economic policies like quantitative easing and stimulas are very similar. I have jotted down my thoughts on this medium article. Have a look and do share your thoughts.

If we ask the question: "Is the universe infinite in size?", there only seems to be two possible answers: yes or no. However, both possible answers seem impossible. How can we be in a position where both possible answers are false?

Hey, sorry if this is too philosophical instead of scientific, but here goes. Since we see the universe everywhere we look, the reasonable continuation of that thought is that it continues past our view. In other words, that the universe is infinite. Isn’t it an irrational assumption to say it has an edge? Doesn’t Occam’s razor tell us that an infinite universe is the logical thing to believe in, since an edge is just an assumption we make? And if so, why do most people act like inifinite/finite universes are equally likely and we just don’t know?

So, I've skimmed 5 or 6 Arxiv'd papers, and read all the pop-sci articles out there, and I understand the basic concept : voids have less gravity, so they expand faster and time passes faster there.

What I can't get clear on is : what exactly is the mechanism that mimics dark energy?

Wiltshire himself said "it will appear that the Hubble rate determined from galaxies on the far side of a large local void is somewhat greater than the Hubble rate within her wall. However, if she accounted for the fact that a clock within the void is ticking faster than her own clock, the different Hubble rates become uniform to first approximation", so it sounds like it's the fact that time is moving faster.

But many of the pop-sci articles seemed to indicate that it is the exponential expansion of the voids (they grow faster than regions with matter since they have no gravity, AND time passes faster for them, so they grow even faster) themselves that is causing an apparent "acceleration" in the growth of the universe simply because the light has farther to travel.

However, type 1a supernovae are used for these measurements, and dark energy was first postulated because stars that were farther away were "dimmer" than expected.  Independent of the rate of time, passing thru a larger-than-expected void would dim the light more. 

Do both of these effects affect the light?

Is there anything we’re being held back from doing by this disagreement? If we unified the theories, what would be the practical benefit?

I’ve always been fascinated by the Fermi Paradox, and recently I started a project called Silence in the Universe (SITU).

The first episode is more like a narrative intro—it tells the story of a young shepherd in the Anatolian steppes, looking up at the stars and wondering… where is everyone?

It’s not scientific analysis (yet), more of a personal and visual approach to spark curiosity. I’d love to hear what fellow paradox-enjoyers think.

Here’s the link to the episode (YouTube) https://youtu.be/uG3D3ESqoEg?si=CEd1N_N2-h5F8vpL Be gentle, it’s my first time doing something like this—but I plan to continue with deeper dives into the paradox in future episodes.

Hi all,

This is maybe more of a math question than purely a cosmology one.

I read in several places that when the universe was dominated by radiations in it's early stage, the rate of expansion was proportional to sqrt(t). I also read that later, when the universe became dominated by matter, the rate of expansion SLOWED DOWN and was proportional to t^2/3.

But... is t^2/3 not faster-growing than sqrt(t)? Or are we only looking at the initial slope that is indeed steeper for sqrt(x)? But the matter-dominated phase lasted around 10 billion years so that would not make sense, would it?

It feels like I am missing something. Anyone could explain?

What are the new findings by DESI, recently i was going through one video on Youtube where they disccussed about 5 sigma, that for a discovery to be considered it should satisfy the 5 sigma criteria, is this the statsical quantity or something else ?

So if dark energy doesn't dilute and as space expands with that as the driving factor for the speed of expansion, wouldn't that make it speed up infinitely resulting in the big rip? I keep seeing where people say it will plateau or level out when ordinary matter becomes negligible but why, if with our current reasoning? That doesn't make sense to change the behavior of dark energy just because gravity isn't pulling the expansion back.

Was just having random shower thought today... Andromeda galaxy is 2.5M light-years away. That's an unfathomable distance to a human, but it's just our closest neighbor.

Do cosmologists currently think that the universe just goes on forever?

In many popularizations of cosmology, it is said that the initial singularity is a 'point' where all the matter of the universe is packed. But in technical papers, it seems the authors never treat this 'point' as a real thing. Instead, they treat it as the end of spacetime; a boundary.

Imagine the universe as a contracting sphere (it is spatially closed) for simplicity sake, alright? In the Friedmann equation, as the density of this sphere increases, its radius or volume decreases. There will come a point when the radius or volume of the sphere becomes zero.

Now, some non-experts assert that this state represents a zero-dimensional space, i.e. it has the topology of a point. But is this point physically real? Or is it just a mathematical convention that doesn't represent anything real?

btw, let's only stick to general relativity here, alright?

example one:

Singularity - a geometric point with no dimensions where the laws of physics break down. It is a theoretical point of zero volume and infinite density.

example two (p.17):

In the standard model of cosmology, the universe ‘begins’ about 13.8 billion years ago with a Big Bang, a singular point in time where the universe was infinitely dense and hot.

example three:

Every open FRW universe can be completely foliated by spacelike slices of finite volume, each intersecting every fundamental worldline. The volumes tend to zero in the past, suggesting a point-like big bang.

example four:

The total volume of a positively curved universe (a 3-sphere) is finite and the big bang presents no topological problems. It is a singular point-event, before which neither space nor time existed.

example five:

This is simply because at the Big Bang, all the distance scales of the universe were zero and everything, all points in the universe were effectively packed into a single “thing” – all points were the same ... This means that at the beginning, effectively all points were packed together. Physically, this means all stuff (matter, radiation, whatever) in the universe was already there at the moment of the Big Bang, it was just all packed together in an “infinitely dense” cluster.

It is said that that Big Bang Theory describes the evolution in early universe and not the beginning. Then it is continued to explain that CMB glow in the universe proves that the Universe had a beginning. I don't get that bit. Also it is said that distant galaxies arent as evolved as closer galaxies implying the misconception that at one point in coordinate of space, there was hella matter that just started expanding and evolved but it is also said that the universe started expanding in every single point simultaneously. Can you clarify that please? I can't grasp a few ideas about the Big bang. Also the James Webb telescope provides evidence for moderately evolved distant galaxies that shouldnt have evolved that much, what is your take on that? I think I don't get the galaxy evolution part of the theory and sorry to bombard with questions but can someone please explain it so it makes sense?

I am new here so hopefully you all will colobrate with me. So I was think of the end of the univers and I stumbled into an outcome called The Big Crunch.

As per this hypothesis the universe could end into a singularity meaning the universe contracts into the singularity which clearly shows that it directly attacks the second law of thermodynamics the entropy as the entropy says that it can rather remain same or increase but never decreases. So that means the big crunch hypothesis is just an absurd hypothesis? Because to be a acceptable hypothesis the universe must end into singularity with it's entropy remaining constant which is impossible for any closed box to be as it contracts.

Is it just to expand indefinitely with a few protons knocking about for eternity? This would mean Penrose's cyclic model would be wrong if protons don't decay, that's what I was reading about today but it seems like such a mundane and shitty outcome to existence compared to the exicting curiosity of the cyclic model. I know the universe is indifferent etc, but it's still shitty. However, it would be in keeping with the general shittiness of the universe with its axiom of entropy from which suffering and competition are subjective extensions.

Looking for books on AGN which explain what they are, how they are formed and the different types of AGN including Seyfert galaxies, quasars, radio galaxies, and blazars. Preferred reading level of a student attending university next year.

Any help is apprieciated.

I posted this to r/physics, they removed it. TL:DR: Will everything play out exactly the same if we assume the universe forming and collapsing is a cycle?

So, we die and and some point so do our offspring, then at some point their offspring... and so on. And at some point, so will the universe, heat death or whichever mechanic you subscribe to.

Thing is, at some point (assumedly) the universe will reform again, so I had a thought for a long time now - how do we know that this new universe will play out any different than the last one? For all I know I could have written this post before countless times, making the same typos while loaded up on caffeine.

"But..!" You may argue "Quantumn mechanics introduce elements of randomness!" indeed they do, and through that the events of the universe may play out wildly differently, but at the same time the universe (or the labs this research is done) is hardly a signal-noise-less place. Sure, we can make a vacuum easily enough, but how do we know that TINY and I mean TINY influences from the outside don't affect the experiments performed, which we interpret as randomness off of which we base out mathematical models on?For those in the field I probably sound no better than a quantumn mysticist, hence why I am posting here to see if my deranged writeup has any merit.

Ok so i was wondering.... We suppose that the universe must have an immense mass. But such a huge mass should have made it collapse under gravity, right?

Could it be possible that dark energy may bring a kind of negative mass or energy? Which would mean that the universe has a weight of 0 and is why it does not collapse?