New 3D Cosmic Map Raises Questions Over Future of Universe, Scientists Say (theguardian.com) 63
The biggest ever 3D map of the universe, featuring more than 6m galaxies, has been revealed by scientists who said it raised questions about the nature of dark energy and the future of the universe. From a report: The map is based on data collected by the Dark Energy Spectroscopic Instrument (Desi) in Arizona and contains three times as many galaxies as previous efforts, with many having their distances measured for the first time. Researchers said that by using this map, they have been able measure how fast the universe has been expanding at different times in the past with unprecedented accuracy.
The results confirm that the expansion of the universe is speeding up, they added. However, the findings have also raised the tantalising possibility that dark energy -- a mysterious, repulsive force that drives the process -- is not constant throughout time as has previously been suggested. Dr Seshadri Nadathur, a co-author of the work and senior research fellow at the University of Portsmouth's Institute of Cosmology and Gravitation, said: "What we are seeing are some hints that it has actually been changing over time, which is quite exciting because it is not what the standard model of a cosmological constant dark energy would look like."
Prof Carlos Frenk, from Durham University and a co-author of the research, said that if dark energy was indeed constant in time, the future of the universe was simple: it would expand on and on, for ever. But if the hints found in the map stood up, that would be called into question. The research, which has been published in a series of preprints â" meaning it has yet to be peer-reviewed â" reveals how the team first created the 3D map, then measured patterns in the distribution of galaxies that relate to sound waves that occurred in the early universe, known as baryon acoustic oscillations.
The results confirm that the expansion of the universe is speeding up, they added. However, the findings have also raised the tantalising possibility that dark energy -- a mysterious, repulsive force that drives the process -- is not constant throughout time as has previously been suggested. Dr Seshadri Nadathur, a co-author of the work and senior research fellow at the University of Portsmouth's Institute of Cosmology and Gravitation, said: "What we are seeing are some hints that it has actually been changing over time, which is quite exciting because it is not what the standard model of a cosmological constant dark energy would look like."
Prof Carlos Frenk, from Durham University and a co-author of the research, said that if dark energy was indeed constant in time, the future of the universe was simple: it would expand on and on, for ever. But if the hints found in the map stood up, that would be called into question. The research, which has been published in a series of preprints â" meaning it has yet to be peer-reviewed â" reveals how the team first created the 3D map, then measured patterns in the distribution of galaxies that relate to sound waves that occurred in the early universe, known as baryon acoustic oscillations.
Presumptions (Score:2)
I've never really thought of this before, but my understanding is that we know what the universe consisted of at its beginning, more or less, based on observations of things like the CMB.
I've also heard numerous musings on other dimensions, other universes, etc. My understanding of those is that they wouldn't share the same spacetime that we did here in this universe. But is that necessarily a fixed reality? Would two universes potentially be able to interact, with matter and energy that was not part of
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Would two universes potentially be able to interact, with matter and energy that was not part of the original consist of our universe?
so at pretty much every moment, with every quantum interaction, the universe duplicated and forked. thats a lot of stuff. a lot of mass. i have trouble believing this
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The problem is the alternatives are even worse.
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Didn't Eddington already make a mockery of Occam's Razor when he noted that the universe is not only stranger than you imagine, but stranger than you can imagine? Can you imagine a universe where Occam's Razor is simply a psychological human rationalization, not an actual thing?
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Hm, I wonder if people will try to induce failure in the AI by posing logical conundrumsand things like that. The AI will have to be resilient to all that I mean remember that Star Trek episode where Kirk causes a robotic probe to destroy itself:
KIRK: "Everything Harry tells you is a lie. Remember that! Everything Harry tells you is a lie!"
MUDD: "Now listen to this carefully, Norman laddie. I AM LYING."
People could type harassing stuff like that in their comments which I presume would only serve to make the
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Since the attenntion mechanism easily deals with logical contradictions without crashing, why assume classical logic is any kind of prerequisite for intelligence, artificial or otherwise?
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You seriously don't see the value in trying to understand how the universe works?
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I do see it. I was just kidding around.
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Why do you think they termed it dark energy? Just about every physicist would tell you it is merely a place holder. And lacking any evidence it was changing, they just used the least innocuous idea and that happily coincided with Einstein's equations. This result is not yet evidence, but as they mentioned, is a hint that maybe dark energy is not constant. We know something is pushing galaxies apart even if we cannot say, "Aha! we now know".
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We know something is pushing galaxies apart even if we cannot say, "Aha! we now know".
No, we do not know that. There are plenty of alternative theories, which (at least try to) explain the redshift changes with other means than expanding universe and dark energy (explaining the changes with e.g. light speed changing over time). And with more and more evidence popping up making dark energy behave stranger and stranger, we should be looking at those alternative theories more closely.
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What if your reaction to strangeness says more about you than about the universe?
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What if your reaction to strangeness says more about you than about the universe?
Care to explain? To think outside the box, to question existing theories - what DOES it say about the universe in your opinion?
I'm just thinking that introducing variability to dark energy (a flaky placeholder-concept in the first place) does remind a lot about epicycles, which were needed as a correction to the geocentric model of the universe to explain the motions of the other planets.
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Serious science involved (Score:5, Interesting)
This study is mind boggling, that humans have put so much time, effort, (and money) into understanding the universe is inspiring.
Just skimming through the research, you can see the massive amount of work involved, from other research, to the equipment used:
https://iopscience.iop.org/art... [iop.org]
Re:Serious science involved (Score:4, Insightful)
Yes it is. It's interesting and not just about short-term payoffs. We have to try to understand the laws that govern the universe and explore it as much as possible regardless of whether it provides "practical benefit" .. the practical benefit is the knowledge of the unknown.
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Six million galaxies mapped. It was barely 100 years ago that it was discovered that Andromeda was its own galaxy, rather than just another nebula in the Milky Way. That is **SO** cool.
aether (Score:3, Interesting)
I may just be uneducated, dark energy seems like the aether of our time.
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https://science.nasa.gov/missi... [nasa.gov]
they found extra matter but didnt adjust the dark matter speculations
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Has aether theory been disproved or just other interpretations seem to us to work better for limited cherry-picked examples?
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So, does the Michelson-Morley experiment successfully detect dark matter because it bends light, thus proving the aether does in fact exist after all?
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No.
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You confidently state this as fact, that MM disproved the aether. Can you provide details, or you are just uncritically repeating a story you've been told?
If you can provide details, then I'm sure you can also provide us a summary and analysis of Dayton Miller's years of detailed follow up work. You can start with how he used the ether drift data to calculate the axis of solar system movement in the galaxy. Or the more recent ether drift experiments that have also confirmed its existence. Doubtless yo
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It's definitively proven there is no aether. But there are numerous things called fields that constitute what we consider spacetime, and at every point in these expanding, uniform fields there are interactions with other fields which we interpret as constituting matter, energy, and physical interactions. Changing, correlated values in the photon field and electron field are what propagates electromagnetic waves over time, over space.
That, to me, is not all that different than theorizing there's an aether in
Relativity (Score:3)
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No, now the aether is called spacetime or quantum foam. We can detect vibrations in the spacetime caused by gravitational waves. However, we cannot detect motion with respect to the spacetime, as proven by the Michelson–Morley experiment. Furthermore, we now know that empty space is full of stuff [wikipedia.org].
Generally, people take this as proving that the aether as thought of in 1900 doesn't exist, much less the aether from 200 BC. However, there are various aether theories [wikipedia.org] which are consistent with all known sci
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In my opinion, luminiferous aether was a specific thing that they thought existed. As I understand it, dark energy and dark matter are essentially just placeholders. It looks like there's energy there and it looks like there's matter there. These ideas are not as specific as saying, definitely something with specific properties like carrying light exists.
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In a way, you're right. But it's not right to be dismissive of it.
Aether was a concept used to explain certain observed phenomena. So is dark energy (and dark matter). It successfully explains many observations, and ANY replacement theory will need to do at least as well at explaining those observations. Aether encountered Michelsonâ"Morley, which it couldn't explain. It will not be unexpected if dark energy encounters something analogous. But so far there's no alternative that works as well.
Not Aether, Vacuum Energy (Score:5, Interesting)
I may just be uneducated, dark energy seems like the aether of our time.
Dark Energy is very different from the aether. The Aether was hypothesised as the medium for light waves since, up to that point only mechanical waves were understood and they required the oscillation of some medium. Since there was nothing in the vacuum for light the idea was that there was some magic aether that was the medium that light propagated through.
Dark Energy is effectively the energy of the vacuum which drives the expansion of space. It's not a physical medium at all and, in fact, we really do not have a clue exactly where this comes from. If you try to calculate it based on what we know of the Standard Model you end up ~100+ orders of magnitude away from the measured value so that's a good measure of how little we understand it. We've known for quite a while that it exists though and this paper seems to suggest it is not constant either which is interesting.
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Yes and no. Popular journalism makes it seem like something special. But really it's just the idea that there might be something that acts like matter that we can't detec (yet)t. With aether it was given an assumption that there should be a transmission medium for light (and later possibly gravity), because light probably is just like sound and needs a medium. It started with the idea that light is like sound. Dark Matter on the other had came about as an idea because of experimental measurements, the u
Re: aether (Score:2)
The exact opposite.
Aether was an idea about the nature of reality which, as soon as Michelson-Morley got experimental data, was shown false.
Dark energy is experimental data which as yet has no explanation about what it truly is. All we say is "there must exist some underlying reality which will explain these observations, even though we don't yet know what it is".
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"Dark Matter" and "Dark Energy" are just placeholders, used to designate where the edge of our knowledge is. We know that X + Y + Z = A, but we don't know what Z is so we call it "Dark" for now.
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no, because the aether actually made sense.
55+ Million galaxies. (Score:3)
That's a _lot_ of galaxies. Shame we have limited lifespans and no FTL-travel. Would love to hop on to an Elite Dangerous style spacecraft and explore the universe.
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Don't forgot, most find humans delicious.
Re: 55+ Million galaxies. (Score:2)
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So far, I believe so. The measurements disagree with the theory by so much that even the discovery of all those extra galaxies doesn't explain it all. We don't "need" dark matter, but a better explanation isn't here as yet; we don't know where there's enough matter to account for the theory, and we don't have alternate theories (including the prerequisite mathematics) that match the measurements.
And dark matter isn't a type of matter, it's not necessarily a "thing", but it's a place holder term for the dis
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Would love to hop on to an Elite Dangerous style spacecraft and explore the universe.
You mean explore the local galaxy. Elite Dangerous ships are not capable of leaving the galaxy they were created in. But otherwise, your point still stands. :)
Dark Energy (Score:3)
I've never really put much stock in the dark energy theory. For one - its another "placeholder" theory. IE, this thing exists with no proof because our equations don't work with this as a fudge factor.
That said, even assuming dark energy exists, and is what is driving expansion of the universe, then there's no guarantee that it will continue to strengthen over time. Indeed the expansion hasn't just been accelerating since the beginning. At the very beginning of the big bang expansion was much more rapid, then slowed down dramatically, then has been gradually speeding back up again.
The thing is, without knowing what caused the first slowing of expansion, there's no guarantee that expansion won't slow again eventually.
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Do you ever get the impression they're making it up as they go along?
"Dark Matter" and "Dark Energy" are just code for "our math turned out wrong, and we don't know why".
Re:Dark Energy (Score:4, Insightful)
Well, yes, they ARE making it up as they go along. The universe didn't come with a handbook. Scientists have to try an infer the rules by observing the behaviors. At any given point, the sum total of all scientific theories still just amounts to "the best we've come up with so far."
There is no shame in not knowing why our models don't match our observations. Solving those mysteries is an ongoing effort, and it requires brilliance as well as data (and is in fact impossible to do if key data haven't been discovered yet). So, the "best we can do so far" models need placeholders for the things that don't line up.
The plan has always been to get rid of "Dark Matter" and "Dark Energy" once we figure out what's really going on.
Known Unknowns (Score:4, Informative)
I've never really put much stock in the dark energy theory. For one - its another "placeholder" theory.
It's not a placeholder theory because it is not a theory at all. It is a measurement of the vacuum energy of space. The theory part comes in explaining where that energy comes from and unfortunately we don't really have a good theory that explains it at all. Indeed, if you try to calculate it from the Standard Model then you end up 100+ orders of magnitude wrong.
Think of it like the ancient Greeks measuring the radius of Earth and then realizing that there was a lot of the surface of the planet that, given their measured curvature, must logically be there but that they had zero knowledge of. It's the same thing here. Our observations tell us that the vacuum has an inate energy that drives its expansion but we have no clear where it comes from or what it is, all we know is that it is there.
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Think of it like the ancient Greeks measuring the radius of Earth and then realizing that there was a lot of the surface of the planet that, given their measured curvature, must logically be there but that they had zero knowledge of.
That example only works in hindsight. Yes, they had a somewhat accurate calculation of the size of the Earth, and therefore could potentially guess that there was "something" between Europe and swinging back around to Asia, but that is only now accurate because we've determined the actual size of Earth and what that thing in between is.
At the time until proven otherwise it could have just as easily been that their math was wrong the whole time.
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That example only works in hindsight.
No it does not just work in hindsight. The Greeks knew basic geometry - indeed they were the ones who came up with it! They knew that the Earth was a sphere and in 240 BC Eratosthenes measured the radius with an accuracy of a few hundred kilometres. This meant that they knew the circumference and the surface area of the planet and they also knew how much they had explored which was a lot less than the total area.
At the time until proven otherwise it could have just as easily been that their math was wrong the whole time.
It WAS proven otherwise by the ancient Greeks themselves! Mathematical proofs are absolute. Th
Dark Fiddler? Dark Tweaker? Dark Rigger? (Score:3)
Since they have been coining various Dark X's to plug gaps in our knowledge*, to follow the pattern they will invent the "Dark Fiddler" to explain the changes over time.
* Such as Dark Matter and Dark Energy. Perhaps these are comparable to "ether" and "epicycles": invented objects or forces to attempt to model mysterious movements and behaviors.
Survey telescopes (Score:2)
If you're wondering why so many recent telescopes seem to be wide-angle survey telescopes, this is why. We've gotten to the point where the precision of incoming data is sufficient for first-order analysis. Now the priority is on collecting such data from huge swaths of the sky -- basically anywhere our own galaxy isn't screening us. The problem used to be that there wasn't time to analyze that much data, but then we started to realize how much more information is still in unprocessed raw data, even decades
The Future of the Universe: (Score:2)
just one more thing to worry about.
How will I ever ... (Score:2)