New Type of Dark Energy Could Solve Universe Expansion Mystery (nature.com) 63
Cosmologists have found signs that a second type of dark energy -- the ubiquitous but enigmatic substance that is pushing the current Universe's expansion to accelerate -- might have existed in the first 300,000 years after the Big Bang. From a report: Two separate studies -- both posted on the arXiv preprint server in the past week -- have detected a tentative first trace of this 'early dark energy' in data collected between 2013 and 2016 by the Atacama Cosmology Telescope (ACT) in Chile. If the findings are confirmed, they could help to solve a long-standing conundrum surrounding data about the early Universe, which seem to be incompatible with the rate of cosmic expansion measured today. But the data are preliminary and don't show definitively whether this form of dark energy really existed.
"There are a number of reasons to be careful to take this as a discovery of new physics," says Silvia Galli, a cosmologist at the Paris Institute of Astrophysics. The authors of both preprints -- one posted by the ACT team, and the other by an independent group -- admit that the data are not yet strong enough to detect early dark energy with high confidence. But they say that further observations from the ACT and another observatory, the South Pole Telescope in Antarctica, could provide a more stringent test soon. "If this really is true -- if the early Universe really did feature early dark energy -- then we should see a strong signal," says Colin Hill, a co-author of the ACT team's paper who is a cosmologist at Columbia University in New York City.
"There are a number of reasons to be careful to take this as a discovery of new physics," says Silvia Galli, a cosmologist at the Paris Institute of Astrophysics. The authors of both preprints -- one posted by the ACT team, and the other by an independent group -- admit that the data are not yet strong enough to detect early dark energy with high confidence. But they say that further observations from the ACT and another observatory, the South Pole Telescope in Antarctica, could provide a more stringent test soon. "If this really is true -- if the early Universe really did feature early dark energy -- then we should see a strong signal," says Colin Hill, a co-author of the ACT team's paper who is a cosmologist at Columbia University in New York City.
I've read this book and didn't like it. (Score:2, Insightful)
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Dark energy and dark matter are two different things. Dark matter is some form of matter that weakly interacts with other particles, save, so far as we can tell, through gravity. Dark energy, whatever it is, is what appears to be causing the increased rate of expansion of the Universe. It may be part of space-time geometry, or it may be in fact be a new kind of fundamental interaction. But the alternative is what exactly? To throw out theories like GR which have survived pretty much ever test ever thrown at
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I'm thinking maybe it's from the spirit world.
Well, maybe not, but it would explain a lot.
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The rate of expansion is equal at all points, which is inconsistent with a differing rate of expansion that would occur from spinning. The spinning hypothesis was one of the first things investigated. There's no rotational shift in any direction in the sky.
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Spinning around what axis?
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Pretty sure GR doesn't support the notion of simultaneity, but simultaneity has been demonstrated at the quantum level. So GR, at best, doesn't always apply....
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Citation needed. No really, if that's true, I'd like to understand (though I doubt I'd get a good understanding).
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It's true. We know quantum mechanics and general relativity are incompatible on many numbers, including simultaneity which holds for QM but not for GR. You can google "why is general relativity incompatible with quantum mechanics" and get a wealth of hits, with explanations ranging from the highly technical physics pro to grade school. Pick your level of difficulty. :-)
Re: I've read this book and didn't like it. (Score:2)
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> so commenters can crowd source peer review it?
Why not? It's how we decide complex issues like vaccines. Now we can extend it to astrophysics. I'm still waiting on where my favorite Hollywood celebrity sits before I make a decision on this "dark energy" though.
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Perhaps those testicles *are* dark matter. You don't question DM's effect on itself.
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For a gentleman are several rules he should consider in a civilized conversation:
a) avoid politics
b) don't make jokes about people with gluten-allergies
c) don't make jokes about people who speak bad english - after all they speak a second language
Not so sure why a) is so important to the Britts ... but I hope you get the hint with b)
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That is not a joke ... it is just silly.
But well, some people consider being silly is joking.
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c) don't make jokes about people who speak bad english - after all they speak a second language
And especially when they're Americans speaking it as their first language
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Peer review isn't supposed to detect fraud. It's supposed to filter (some of the) stupid.
Replication detects fraud, error and luck.
Re:I've read this book and didn't like it. (Score:5, Insightful)
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Not so. GR showed that Mercury's momentum around the Sun is equivalent to enough mass to explain the discrepancy. The same effect causes a slight change in the orbits of all of the other planets, but it's only enough to be observed with Mercury.
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I believe you just confirmed what the anonymous coward said -- Newtonian gravity had to be replaced by general relativity to explain Mercury.
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Yeah, but you needed GR to explain the mass. Newtonian physics alone was hitting a wall on Mercury.
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No it doesn't. You can't get a precessing orbit just by changing the mass, unless you change it continuously. And anyway, most of the effect comes from changes in the flow of time.
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I believe you just confirmed what the anonymous coward said -- Newtonian gravity had to be replaced by general relativity to explain Mercury.
No it had not. Why would it?
a) There is nothing special about Mercury.
b) for anything related to mercury GR makes no difference related to Newton
In general: in our solar system is nothing at all that makes/has a difference between Newtion's and Einsteins's equations.
GR is relevant for atomic clocks in satellites: and that basically is it.
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add more dark matter to the equation
There is no dark matter or dark energy in any equations. That is what the physicists mean by "dark". That they have equations for *regular* matter that we see and touch and feel, but the equations are off of what we observe by a factor of X. What is causing that X? We don't know. Instead of calling it "we don't know", we just call it "dark"
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It's dark circles all the way down! (Maybe some eye-cream would help.)
Dark Energy (Score:3)
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You just described theoretical physics.
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In every other measurement we make, the Universe is remarkably homogenous. In fact, Inflationary Cosmology came into existence because of the observed homogeneity of the observable universe, which requires significantly more parameters to be "just so" with standard Big Bang cosmology. So to declare that we happen to be in an abnormal region of the Universe essentially goes against a half century of observation, and strikes me as a bit of special pleading to get around what appears to be the reality; that th
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Far more than half a century. We've spent the better part of a millennium slowly knocking Earth out of any special position vis-a-vis the universe. At this point, that's a pretty hard hypothesis to start with, requiring extraordinary data to support.
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Phlogiston V 3.0 (Score:2)
Cosmologists have found signs that a second type of dark energy -- the ubiquitous but enigmatic substance that is pushing the current Universe's expansion to accelerate -- might have existed in the first 300,000 years after the Big Bang. From a report:
I'm sure the astrophysicists can argue long and eloquently for the existence of dark matter and dark energy but somehow this stuff still always has a 'phlogiston' vibe about it.
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Other not-directly-observable 'universes'? (Score:2)
By that, when I say universe, I mean space where direct observation is possible in terms of light, that is the classic observable universe.
If you have a very, VERY large space, you can have multiple 'big bang-like events happening a large number of times, overlapping, so far apart that no light that happens in one is observable in the others before entropy makes all traces of them unobservable - making each a separate observable universe in the same big space.
In most ways, this would act like the universes
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This is the concept underlying eternal inflation, that different regions of a much larger space exit inflation at different times, but because of the expansion of space, those "bubbles" are too distant from each other for any kind of communication (by which cosmologists mean any exchange or interaction of fundamental interactions). But as you say, the overall much larger space would still exist by a common set of physical principles. The first big test of all this will be finding primordial gravity waves wh
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This is dark energy, not dark matter. Two different things.
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This is dark energy, not dark matter. Two different things.
Or not.
Just like "real" energy and matter are equivalent if you go fast enough, maybe dark matter and dark energy are just sides of a dark coin.
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Do we know if E = mc^2 applies to Dark Matter and Dark Energy?
Re:Meaning they found another error in their calcu (Score:4, Informative)
The term "dark" in these two contexts does not imply any sort of relationship. We have an energy of movement observed and we have a gravitational effect observed. The "dark" aspect of both of these just means "unknown". Energy is just energy... this isn't a new type of energy that we're looking for for dark energy... we're looking for the source of that energy. For dark matter, we can see the effects of things orbiting around a point, but we cannot see anything there. It might be regular matter cleverly cloaked (although that hypothesis is looking less and less likely as we throw more tests at the problem).
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The phrase "new type of dark energy" used in the headline is misleading. It is better stated as "new dark source for energy".
Correction: (Score:1)
Oh hot damn. Please s/matter/energy/.
So the specific point misses and I retract it. The general point applies here too though:
Implying dark *energy* is a particle is even *more* silly.
The Dark Energy is so dense (Score:1)
Just one more dimension (Score:3)
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Subir Sarkar and 'no acceleration' (Score:3)
Subir Sarkar [ox.ac.uk] is a professor of theoretical physics at Oxford. He has done important work is providing evidence that 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. He 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.
Watch his lecture at Oxford [youtube.com], or his shorter talk with Sabine Hossenfelder [youtube.com] (no slides though).
If his findings hold up to scrutiny, this will lead to the Nobel Prize for that acceleration being no longer true.
This is exciting, since it removes one mystery about dark energy. More importantly, it shows the rigors of the scientific method.
A summary of recent discoveries & speculation (Score:2)
What we know:
there are many unknowns in our astronomical models: the age of the universe, dark energy, dark matter, as well as the 'missing' matter... which is regular baryonic matter that we observe in quantities smaller than we expect.
What we are slowly finding out:
Black Holes:
Conditions in the early universe had unexpected wrinkles and consequences. Micro black holes and impossibly large (based on current models) black holes both unexpectedly formed, and galaxies may have formed earlier than expected as