Dark Energy Debunked? Cosmic Acceleration May Be an Illusion (sciencedaily.com) 88
alternative_right shares a report from ScienceDaily: A new analysis of more than 1,700 supernovae is questioning whether the universe is really accelerating at all. After accounting for the ages of the stars that produce these explosions, researchers found signs that cosmic expansion may actually be slowing. They also argue that the apparent acceleration changes with direction, which would be difficult to explain with dark energy. Other cosmologists dispute the conclusion, setting up a major test for upcoming observatories. The analysis has been published in Monthly Notices of the Royal Astronomical Society.
The conclusion is disputed, though. The report mentions a separate paper co-authored by Professor Maria Vincenzi, also at the University of Oxford, that "concludes that observations continue to support an accelerating universe."
The conclusion is disputed, though. The report mentions a separate paper co-authored by Professor Maria Vincenzi, also at the University of Oxford, that "concludes that observations continue to support an accelerating universe."
Not an expert (Score:1, Interesting)
All these factors seem to indicate the inverse of the claim, however, the universe could easily be like the seasons on earth, an ebb and flow of direction based on forces we dont know, or have happened over x million or billion of years ago are affecting us now.
Understanding the universe is like understand
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The usual assumptiom is that there is no source of the big bang, everything banged.
With enough mathematical wrangling, you could probably make current observations compatible with a centered big bang (far enough on the edge you might not be able to tell the difference). But it would be blasphemy to cosmologists to even try.
Re:Not an expert (Score:4, Funny)
everything banged.
Even slashdotters?
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There are more things in Heaven and Earth, ZiggyZiggyZig, than are dreamt of in your philosophy
Re: Not an expert (Score:3, Interesting)
"The usual assumptiom is that there is no source of the big bang, everything banged."
That seems like it would require a lot of faith.
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They have enough cosmic coincidences to deal with, without a cosmology where our view of the universe is privileged in such a way it makes it look unprivileged. Why would science Satan do that?
Re: Not an expert (Score:5, Informative)
Nope. No matter where you look in the sky, on large enough scales it looks the same. There's no indication that things are significantly different in any particular direction.
There can't be a 'source' of a Big Bang that looks like that. It has to happen everywhere or the sky would show signs that it was all accelerating away from a single point.
What we can say is we don't really have much ability to figure out what happened early on. The conditions are too extreme and we don't have any way to model what might have been going on. That's not faith either, that's, "We don't know and might never be able to figure it out".
Re: Not an expert (Score:5, Interesting)
This is the prevailing dogma, but has recently been challenged from more recent observations. (In defense of the dogma, we have very aggressively tested for preferred rotations with local experiments involving high energy particles. If there *is* a preferred rotation, its effect is vanishingly small, to the point of being functionally indestinguishable from flat spacetime at local scales, to an astonishing level of precision. This strongly suggests 'sampling error' for JWST data that follows)
https://academic.oup.com/mnras... [oup.com]
Recent large area surveys by JWST suggests that there is a preferred rotational direction and axis to disparate galaxies. Such a finding is inconsistent with the presumption of widescale anisotropy. (But again, that's a very bold statement)
It may yet be ruled out through further observations as a sampling error, but the statement that there are *no* indications isotropy is incorrect. The mere existence of this survey says otherwise.
If there really is a universal preferred rotation, then a 'fuzzy', 'proximal' position could be given as a baricenter. It wouldnt be definitive; too much can happen as random events to compute an exact baricenter, but a statistically probable, proximal area could be defined with some confidence threshold.
Again, *assuming* the JWST readings arent just a sampling error. Which it probably is.
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There's also evidence of a temperature asymmetry in the CMB, it's a tiny bit warmer looking in one direction than the other. It's too small a signal to conclude anything from yet, and might be an artifact of the models, but it seems things aren't as uniform as we thought.
Re: Not an expert (Score:4, Insightful)
If the initial finite volume for a finite big bang was large enough and we were not too close to the centre or edge, it would look like that. All the proof could be beyond our current measurement capability.
Re: Not an expert (Score:3)
The observation is that on large scales, everything is moving away from everything else. No assumption needed. Although explaining the mechanism is hard, with the obvious one that the universe started off tiny and empty space filled in around it -- the big bang. The cosmic microwave background radiation confirms that the universe used to be much hotter, which fits if the universe was once denser (less space between things)
Re: Not an expert (Score:5, Informative)
with the obvious one that the universe started off tiny and empty space filled in around it -- the big bang.
No, there was no "empty space" around it. The space itself expanded in the cosmic inflation, per current theory.
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Which I've always hated because it makes no sense. If space itself inflated, what did it inflate into? It's illogical, from any perspective, to say the universe was a speck of energy that suddenly expanded to create itself. If it expanded, it had to expand into something. You can't create yourself. If you say that, then all you've done is recreate, "In the beginning
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Exactly the thought I had when hearing "the universe is expanding". Was the universe always 1 Universe in diameter regardless of what form it was in (a hot, dense ball)?
Definitely the kind of thing that defies human common sense. I put it on the shelf next to relativity.
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Which I've always hated because it makes no sense.
Lots of things make no sense in physics. How can a single particle split itself in half and the interfere with itself but only if you're not watching too hard? Nonsense!
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Which I've always hated because it makes no sense. If space itself inflated, what did it inflate into?
There is no such thing as "space", apart from "spacetime.". You can go, "there's a lot of space between our sun and Alpha Centauri" but if you were moving in that direction at close to the speed of light, instead you'd go, "hey, these two stars are super close to each other." Arbitrarily so: you can make them as close as you like, you can put as much energy into changing your frame your reference to make them centimeters or millimeters apart if you want to. Where did all that space go?
You can't really talk
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Spacetime is created through energy becoming matter. The Big Bang was "merely" energy becoming matter. As long as that continues, spacetime will continue "growing".
I want to know what caused energy to start becoming matter. Asking where the energy came from to begin with is like asking about where God came from.
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The whole reason no faith was required to hypothesize the Big Bang, is that everything looks like that's what happened. Pick a direction (any direction) and the further-away stuff is moving away faster than the closer stuff.
If you're looking for faith, it's here, but it's not that. The faith required by science is that our senses sense reality. That is the completely-unfounded religious axiom of every scientist: that the universe is as it (roughly) appears to
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There is one objective fact that supports that axiom: no matter who makes the observations, what direction they look and when, they get the same results. This strongly suggests that what we are observing is objective reality, not some subjective vision that can vary from one observer to another.
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or a lot of Astroglide
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This attitude is common among religious believers who face accusations that the reason their beliefs require faith is because there is otherwise no good reason to believe them.
The cold hard fact is that ALL knowledge is uncertain. We can't know anything for sure, because all our sources of knowledge are suspect. The experiences we have might all be illusions. Things that seem obviously self-evident might only seem so because our brains are broken (or otherwise lying to us). We have no means, even in the
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This attitude is common among religious believers who face accusations that the reason their beliefs require faith is because there is otherwise no good reason to believe them.
The attitude is also common among the "well trained". They will say "we know this..." and often the proof is that the theory has held for some number of years so that makes it such that it must be true. And it seems that in pretty much every field greater than 50% of the experts are just "well trained" and don't really have a feel nor an actual understanding of anything. "well trained" can typically do that math but don't understand how ANY of the math relates to reality. And religion is all training
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"The usual assumptiom is that there is no source of the big bang, everything banged."
That seems like it would require a lot of faith.
Not if you are well versed in cosmology.
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The usual assumption is that there is no source of the big bang, everything banged.
To be more precise, without evidence, then any hypothesis of what happened is just a guess, and can never be tested.
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Some guesses are clearly wrong as they can be tested.
When we're talking about what happened before the big bang, what hypothesis can be tested? How do you collect evidence about that?
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It might be unknowable, but we also might, through future study of ultra-dense states, end up with agreement on a cosmology model that explains the Big Bang and does not have it at some invariant t=0 of the universe.
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Perhaps that might be seen as a bit of 'god of the gaps', but it still makes a prediction that there is a form of matter that is dark and should
I don't mind if someone makes a hypothesis that god exists and does things. It's a hypothesis, and can be treated scientifically like any other hypothesis, by experimenting and looking for evidence.
we weren't in a position to prove the Moon wasn't made of green cheese but could in the late 1960s
Before the moon landing, telescopic spectroscopy could only measure the surface of the moon. The inside is still made of cheese: that is my hypothesis.
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...there is no source of the big bang, everything banged.
I thought your mom said she was gonna stop doing those!
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"but weather changes are so significant that our prediction models dont work anymore"
AI weather models may use the past to predict the future but AFAIK conventional models simply use physics so climate change will be factored in by default by dint of registering higher temps at monitoring stations.
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What are you even talking about? They're not Markov models.
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"every galaxy has a black hole, a yet unknown material keep solar systems pushed in, and yet we are moving faster away from the source of the big bang."
These have nothing to do with the universe expanding. It is the space between galaxies that expanding, that's sort of how we measure it, i.e., by looking at near galaxies and far off galaxies (them are further back in time), and observing the differences.
" the universe could easily be like the seasons on earth, an ebb and flow of direction based on forces we
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I see the same with the universe. We have no models, we can only look at what we see before us, and use that information to inform possibilities.
We do not have accepted models. There actually is models that are however kind of speculative. I actually also built my own highly speculative model - just for fun - and while it has some nice explanations, I am very aware, that this is not finished. If you are interested, see https://doi.org/10.5281/zenodo... [doi.org] . And yes, it explains why there would be dark matter and dark energy, but there is no way to interact with it besides gravitational effects.
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If you're truly interested in astrophysics may I suggest Rebecca (Becky) Smethurst's youtube channel:
https://www.youtube.com/drbeck... [youtube.com]
She's an astrophysicist working at Oxford who specializes in super massive black holes. She's also a great communicator who can explain clearly complex concepts without ever dumbing them down. Her channel is a treasure trove of information about astrophysics and cosmology in general.
Plus she's cute. And funny.
Did I mention she was cute ?
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every galaxy has a black hole. This is incorrect. Who says this?
Every (large) galaxy has a black hole (Score:2)
every galaxy has a black hole. This is incorrect. Who says this?
Every large galaxy is believed to have a black hole. Dwarf galaxies (like the Magellanic Clouds) may or may not.
https://www.astronomy.com/scie... [astronomy.com]
https://astronex.net/why-is-th... [astronex.net]
https://science.nasa.gov/missi... [nasa.gov]
The "reality is just messing with us" hypothesis (Score:5, Funny)
The size of the universe is increasing...
but the rate at which it is increasing is decreasing...
but the rate at which the rate is decreasing is increasing...
but the rate at which the rate of the rate is increasing is decreasing...
but the rate at which the rate of the rate of the rate is decreasing in increasing...
[... and so on, ad infinitum...]
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I'm in creases
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These can all be true: the universe is shaping itself into a giant pony.
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You're talking about a Taylor series with alternating signs...
Interestingly, this rules out exponential growth... but not exponential decay.
Accelerating? (Score:3)
The only thing I see accelerating is the rate at which opinion on these matters flip-flops.
Re:Accelerating? (Score:4, Insightful)
Yes, that's called research on frontier science, on the very bounds of our understanding of the universe.
If it wasn't like that, we wouldn't be referring to dark energy as one of the great unsolved problems in cosmology.
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That is not what is happening. What is happening is that someone has a new paper about whether it's true or not. It will probably change few minds.
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And the rate at which people who have no idea what they are talking about express their "opinion" accelerates.
Douglas Adams was right (Score:5, Funny)
I can explain away Dark Matter/Energy in 4 words (Score:4, Insightful)
WE DON'T UNDERSTAND GRAVITY.
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The idea that dark matter/energy can be explained away by a modified theory of gravity isn't a new one and is an active area of research. See: Tensor-Vector-Scalar (TeVeS) gravity as just one example of an (unsuccessful, as far as I understand) attempt.
If you've got a compelling argument for why it's definitely the right path forward, please report it to the folks in Sweden and collect your Nobel prize.
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That's a possibility. One that doesn't obviously have fewer problems associated with it, is simpler, or better supported by evidence than the alternatives.
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There are corrections to gravity that include the current size of the Universe as s term that gives extremely small differences in calculations but explains most observations.
It has a certain allure from an Information Theory perspective and is extremely parsimonious in ask.
But funding is for finding wimps and axons and evidence of mysteries that use the old equations so you are called crazy if your simple theory threatens that gravy train.
Some people say useful physics is too dangerous to fund and we're be
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I'd argue what you should say instead is:
1) We don't (fully) understand how the (fundamental) forces interact at large scales, and/or
2) There are forces at play we have not yet discovered, and/or
3) There is some (new) kind of (exotic) matter or energy in play that for some reason defies classic forms of observation
For whatever reason, scientists seem to strongly favor #3 as a baseline. #2 seems like it's pretty difficult to assess, since it's "wide open", and #3 seems to have some proponents with alternate
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gravity is easy, it is time that is a real mind bender. gravity is created as a function of spacetime when energy is converted into matter. gravity is a function of spacetime.
Why would dark energy need to be homogenous? (Score:2)
the apparent acceleration changes with direction, which would be difficult to explain with dark energy
Is there any competing theory that would explain anisotropic expansion?
Overall, it strikes me as a pretty bold claim to have debunked a "theory" that has zero physical or even high-confidence theoretical underpinnings beyond "something makes stuff move apart faster than it should". Dark energy is little more than a named fudge factor - This is like disproving the shape of jello.
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"Dark Energy" doesn't qualify as a theory. There are at least a few theories that explain the observations labeled "Dark Energy". None of them are generally accepted. So, no, there's no competing theory that apparently explains the "anisotropic expansion", though I've got a partial one (I'm no expert in the field). My theory is that the matter of the universe isn't distributed equally, so some parts have more intense exposure to gravity than others. (I've encountered claims that it's really pretty evenl
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Well, sort of. I really have trouble with the initial expansion, though. I've been assured that we're not within a black hole, and that makes it hard to understand how we ever escaped the Schwarzschild radius. Also time runs slower when gravity is stronger.
But, yeah, I'm no expert in the field.
equation (Score:2)
Dark Energy = Dark Matter times the (Speed of Dark) squared
Re:equation (Score:4, Funny)
You don't say (Score:3)
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Dunning-Kruger at work.
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Don't feel too bad. Einstein did the same thing with his "cosmological constant". Trying to hang onto an outdated idea that the universe was eternal and static. Lemaitre and Hubble demonstrated that he was wrong. And he accepted that.
Lecture by Subir Sarkar (Score:3)
The corresponding author is Subir Sarkar [ox.ac.uk].
He is a professor at Oxford who has done some interesting work about the expansion of the universe is NOT accelerating.
Instead, he is saying that there is a dipole effect because earth, and the galaxy cluster that we are in, are all moving in space, and that gives the effect of accelerating expansion!
He provides compelling evidence (for a non-specialist at least) for what he says and also casts doubts on the evidence for acceleration by analyzing their data (supernovae as standard candles, and their red shift), since a dipole effect is observed on that.
If his hypothesis is confirmed by other research and observations, then the 2011 Nobel Prize for Saul Perlmutter and Adam Reiss maybe for nothing ...
Watch his lecture on Beyond The Cosmological Standard Model [youtube.com].
This latest paper is yet another analysis towards that.
Let us see which hypothesis is supported by the evidence, current and future ...
Beyond my limited knowledge ... (Score:2)
Just my opinion (Score:1)
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I've always assumed dark *anything* was nonsense.
"Dark" just means "we can't see it". Anything that isn't either emitting light or other electromagnetic radiation, or reflecting light from something it's close to that's emitting light or other electromagnetic radiation, is "dark".
The data is, if you look at the motion of the stuff we see, and calculate the motion based on the masses of stuff we see, the trajectories deviate. The obvious thing to guess is that it's the gravity of something (or things) we don't see. This has worked before-- for example, thi
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How about Unidentified Flying Force?
Backreaction conjecture (Score:2)
The directional explanation reminds me of the backreaction conjecture [wikipedia.org]. The basic idea is due to the inhomogeneity of the real universe: as the gravity within each concentration of matter (such as a group of galaxies) pulls it into a tighter clump, the distance between such clumps appears to increase.
I've only come across this idea because of Syksy Räsänen [helsinki.fi], who is famous in Finland for his goth looks and pro-Palestine activities. So the theory doesn't seem to be widely known.