> Leja explained that if you took the Milky Way and compressed it to the size of the galaxies they found, the nearest star would almost be in our solar system. The supermassive black hole in the center of the Milky Way, about 26,000 light years away, would only be about 26 light years away from Earth and visible in the sky as a giant pillar of light.
Imagine how different space travel and exploration would be for a civilization in that stage of the universe! Maybe we come too late and are destined to a lonely, sparse universe.
How's about super massive black holes are massive enough their gravity well accelerates the mass being captured faster than the speed of light, and they plunge back in time. The Universe is self regenerating, by sending super massive black holes back to the beginning of time, where they explode into our universe. Or something like that. Maybe, maybe not.
Penrose has published many papers on ghosts of black holes from another universe (see https://www.livescience.com/63392-black-holes-from-past-univ... for commentary), but 0811.2723 does not have Penrose as an author or state a reference to him by name.
When CMB anisotropies are studied, one question is to see the the universe is isotropic or anisotropic -- these are two different uses of the word isotropic, on completely different scales.
The current prevailing science is saying that the CMB anisotropies are telling us the universe is isotropic...
The linked paper does however talk about an apparent deviation from this standard picture...but that is not what the word "anisotropy" is about in that quote.
Gurzadyan is not the most representative researcher to cite. While doing a PhD in astrophysics I remember a paper coming out where Gurzadyan co-published with Penrose but the paper had obvious flaws due to basic lack of understanding of statistical simulation, and there were many other groups jumping on showing it wrong within a few days..
IIRC the problem was that it was assumed that independent random variables in one space would still be independent after a linear transform (Fourier transform/spherical harmonic transform). I.e. failure in basic statistical algebra stuff underpinning the statistical simulations. This was not nitpicking, the whole result vanished once other groups redid the experiment with corrected algebra.
The talk was all about how Penrose could possibly have been fooled into putting his name on the paper -- and why he would not retract it even after many pointed out the blatant entry level mistakes.
Everything in the observable universe compressed to an extremely uniform degree, as reflected in the cosmic microwave background radiation (CMBR), our earliest "image" of the universe. Variations in the CMBR are on the order of one part per million.
No, we know (because of the CMB) that everything was compressed into a dense plasma until ~300kyr (rough estimate from memory) so there was no way for these structures to survive a previous crunch.
It was just 101 years ago that galaxies outside the Milky Way were discovered and that the universe we can observe grew from being 100k light years to 93 billion light years in diameter. The existence of black holes was first observed in the 1970s. It is a good bet other astonishing objects are yet to be discovered.
Not quite that, we've known about galaxies outside our own (like the Magellanic clouds or the Andromeda galaxy) for a few millenia, and the main reason black holes haven't been discovered for a while because they're black and we needed a theory to know where to look. The current theory of cosmology has overall been pretty stable for a while.
What's interesting there isn't that much the object themselves which are bog-standard as far as celestial objects go, but how red-shifted (and therefore how far away/long ago) they are, which is something the model doesn't quite exclude but does warrant some tweakings of the "initial parameters" of the universe to make it work this way compared to what we expect.
> In 1924, Edwin Hubble established the distance to classical Cepheid variables in the Andromeda Galaxy, until then known as the "Andromeda Nebula" and showed that those variables were not members of the Milky Way. Hubble's finding settled the question raised in the "Great Debate" of whether the Milky Way represented the entire Universe
> we've known about galaxies outside our own (like the Magellanic clouds or the Andromeda galaxy) for a few millenia
Well, we could see them, but we weren't able to distinguish a galaxy from a nebula until after investing multiple centuries into the development of powerful telescopes.
All world lines end in black holes. All world lines start at white holes.
Many Worlds theory is pretty popular. I buy into it. Every thing that can happen does happen, but also... There's this one that goes every black hole spawns a new universe, with slightly different laws of physics, based on the parent universe. So the multiverse starts favouring universes that can make new ones.
Does this mean the Spiderman universe is out there somewhere? Even hypothetically IDK. There's probably some constraint on consistent laws of physics.
If these old galaxies are so dense, could that help explain why their black hole is disproportionately large? With so many stars so close together, maybe they’re gravitationally interacting with each other far more, causing a lot more instability. So you have a bunch of stars knocking each other around and as a byproduct more of them get flung close enough to the center to get captured by the black hole?
(not an expert, just a math guy who occasionally tunes in to this sort of thing)
The pop-sci treatment of what you're describing is the "force-feeding" theory. Black holes exert an outward pressure as they consume material, naturally limiting the rate they're able to grow. There were some recent results lending credence to the growing body of evidence that force-feeding was, at the very least, not a common phenomenon. One such tidbit was discussed here at HN recently [0]. Nobody really knows for sure yet though.
Loving how we are finding mysteries the further back we look. Super massive black holes far larger than our models can account for. Galaxies with more structure and more older population stars.
What is it telling us? Our current ideas are certainly wrong. Looking forward to what it leads us to.
they will keep getting "confused" by older-than-expected objects because the premise is wrong to begin with: the universe is not 13 billion years old, the universe is infinite and eternal.
That means there are an infinite number of exact copies of you typing on HN and on an infinite variety of HN analogues in their respective timelines. Infinity is big!
Most people don’t realize that, unless the universe has positive curvature, it’s infinite in extent according to the usual General Relativity cosmology. We have no evidence that the universe is anything but flat.
"The researchers were also perplexed by the incredibly small sizes of these systems, only a few hundred light years across, roughly 1,000 times smaller than our own Milky Way. The stars are approximately as numerous as in our own Milky Way galaxy...but contained within a volume 1,000 times smaller than the Milky Way."
If the diameter of a galaxy is one-thousandth, then its volume is one-billionth. They can't both be one-thousandth.
Unless it's an almost linear object, its volume is still a power of two or three of its linear dimensions. Many galaxies are quite flat, so their volume could be approximated as X * r^2, though spherical galaxies also exist.
Long thin cylindrical galaxies, where you could see a linear relationship between length and volume, aren't a thing.
I think it's more likely they meant a millionth or a billionth the second time - it's much more common to talk about the size of galaxies in terms of their relative radius than talking about their volume, which you can't directly measure and that's much harder to compute.
Many types of galaxies are nearly flat - all stars are approximately orbiting the center of the galaxy in the same plane. Still, that would mean that the "volume" (essentially the area of the disk) is on the order of one millionth the size of the Milky Way if the diamater is one thousandth.
Of course, it's possible that this galaxy is spherical, so your original numbers apply.
Isn't this yet another shot fired against the timeline of the Big Bang theory ? Lost count now of the observational data that comes up every year or so that either contradicts or is unexplained by the current, prevailing hypothesis.
61 comments
[ 5.4 ms ] story [ 110 ms ] threadPretty crazy galaxies.
There's no reason a previous universe had to form, expand, or stay distributed evenly.
1. Introduction
Since the discovery of the anisotropy of the cosmic microwave background (CMB) radiation by COBE...
The current prevailing science is saying that the CMB anisotropies are telling us the universe is isotropic...
The linked paper does however talk about an apparent deviation from this standard picture...but that is not what the word "anisotropy" is about in that quote.
Gurzadyan is not the most representative researcher to cite. While doing a PhD in astrophysics I remember a paper coming out where Gurzadyan co-published with Penrose but the paper had obvious flaws due to basic lack of understanding of statistical simulation, and there were many other groups jumping on showing it wrong within a few days..
IIRC the problem was that it was assumed that independent random variables in one space would still be independent after a linear transform (Fourier transform/spherical harmonic transform). I.e. failure in basic statistical algebra stuff underpinning the statistical simulations. This was not nitpicking, the whole result vanished once other groups redid the experiment with corrected algebra.
The talk was all about how Penrose could possibly have been fooled into putting his name on the paper -- and why he would not retract it even after many pointed out the blatant entry level mistakes.
On large scales, the universe is incredibly isotropic.
What's interesting there isn't that much the object themselves which are bog-standard as far as celestial objects go, but how red-shifted (and therefore how far away/long ago) they are, which is something the model doesn't quite exclude but does warrant some tweakings of the "initial parameters" of the universe to make it work this way compared to what we expect.
Well, we could see them, but we weren't able to distinguish a galaxy from a nebula until after investing multiple centuries into the development of powerful telescopes.
I feel like the big bang is a white hole.
Come back I have more!
All world lines end in black holes. All world lines start at white holes.
Many Worlds theory is pretty popular. I buy into it. Every thing that can happen does happen, but also... There's this one that goes every black hole spawns a new universe, with slightly different laws of physics, based on the parent universe. So the multiverse starts favouring universes that can make new ones.
Does this mean the Spiderman universe is out there somewhere? Even hypothetically IDK. There's probably some constraint on consistent laws of physics.
[0]: https://www.youtube.com/watch?v=TxWN8AhNER0
If these old galaxies are so dense, could that help explain why their black hole is disproportionately large? With so many stars so close together, maybe they’re gravitationally interacting with each other far more, causing a lot more instability. So you have a bunch of stars knocking each other around and as a byproduct more of them get flung close enough to the center to get captured by the black hole?
The pop-sci treatment of what you're describing is the "force-feeding" theory. Black holes exert an outward pressure as they consume material, naturally limiting the rate they're able to grow. There were some recent results lending credence to the growing body of evidence that force-feeding was, at the very least, not a common phenomenon. One such tidbit was discussed here at HN recently [0]. Nobody really knows for sure yet though.
[0] https://news.ycombinator.com/item?id=40761465
What is it telling us? Our current ideas are certainly wrong. Looking forward to what it leads us to.
My god, it's full of stars
If the diameter of a galaxy is one-thousandth, then its volume is one-billionth. They can't both be one-thousandth.
Long thin cylindrical galaxies, where you could see a linear relationship between length and volume, aren't a thing.
Of course, it's possible that this galaxy is spherical, so your original numbers apply.