Universe Expansion May Be Slowing, Not Accelerating, Study Suggests (theguardian.com) 90
A new study challenges the Nobel-winning theory that the universe's expansion is accelerating, suggesting instead that it may be slowing down as dark energy weakens -- potentially leading to a future "big crunch" where the cosmos collapses back in on itself. "Our study shows that the universe has already entered a phase of decelerated expansion at the present epoch and that dark energy evolves with time much more rapidly than previously thought," said Prof Young-Wook Lee, of Yonsei University in South Korea, who led the work. "If these results are confirmed, it would mark a major paradigm shift in cosmology since the discovery of dark energy 27 years ago." The Guardian reports: The latest work focuses on the reliability of observations of distant supernovae (exploding stars) that led to the discovery of dark energy, work that was awarded the 2011 Nobel prize in physics. [...] By estimating the ages of 300 host galaxies using a different method, the team concluded that there are simply variations in the properties of stars in the early universe that mean they produce, on average, fainter supernovae. Correcting for this systematic bias still results in an expanding universe, but suggests that the expansion has slowed down and that dark energy is waning, the analysis concluded. If dark energy keeps decreasing to the point where it becomes negative, the universe is theoretically predicted to end in a big crunch. The findings are published in Monthly Notices of the Royal Astronomical Society.
Re: Excellent! (Score:2, Insightful)
Say what you want about Biden, but he isn't the President anymore. So, at least my side didn't elect a senile old man for a second term.
Is there a 25th Amendment for astronomers? (Score:2)
Propagation of the vacuous Subject unrelated to your actual topic. The original AC accomplished its goal of poisoning the discussion, but the vacuous Subject can be used for any form of sock puppet food.
So my Subject is partly a joke but mostly a forced bridge trying to reach the actual story. Yeah, I actually think the Democrats should have invoked the 25th on Biden just to prove it can work. Maybe that would have scared the YOB into running for Switzerland before he could continue demolishing the so-calle
Re: Excellent! (Score:2)
We're carefully refining our estimate of our level of ignorance.
Next month's news (Score:5, Funny)
South korean team retract findings, rj45 jack wasn't seated properly leading to erraneous results ..
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South korean team retract findings, rj45 jack wasn't seated properly leading to erraneous results ..
Ha, shows what you know as everyone has come to blame digital. It was an N-type male connector on the instrument.
analog isn't back, it never left (Score:2)
We don't see a lot of blame placed on a 4-20mA, not because it's rare but because it's quite robust.
Re: Next month's news (Score:2)
Ha, shows you know very little about analogue. RF guys NEVER make poor connections or omit grounds.
So back to digital - either network gear or sw bug. Those are the only 2 possibilities. There's also a 3rd - some ai shit doing research for them, but this being south korea, I very much doubt it.
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Ha, shows you know very little about analogue. RF guys NEVER make poor connections or omit grounds.
So back to digital - either network gear or sw bug. Those are the only 2 possibilities. There's also a 3rd - some ai shit doing research for them, but this being south korea, I very much doubt it.
At work my coworker would wear the “don’t blame me it’s a hardware problem” shirt while I wore the “don’t blame me it’s a software problem shirt” at meetings.
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Goes back to the old joke
Q: How many software engineers does it take to change a lightbulb?
A: None. It's a hardware problem.
Q: How many hardware engineers does it take to change a lightbulb?
A: None. We'll just work around it in software.
Dark energy discovered 27 years ago?? (Score:1, Troll)
Somehow, I missed that press release.
As far as I know, there has never been any proof that dark energy actually exists, only theories only conjectures.
Maybe they mean it was PROPOSED 27 years ago.
Re:Dark energy discovered 27 years ago?? (Score:5, Informative)
Dark Energy is the name for the phenomenon an accelerated expansion of the Universe. This was measured by observing distance and velocity of distant supernova, and later also with other techniques (galaxy clusters for exampl). Dark Energy is the additional energy available for driving this, which is not accounted for in light-emitting baryons.
What causes the Dark Energy is another question, and that, indeed, has not been solved ("proven") to date.
Re:Dark energy discovered 27 years ago?? (Score:5, Informative)
Re:Dark energy discovered 27 years ago?? (Score:4, Funny)
Sir it is not mysticism. It's mysticism with math.
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Sir it is not mysticism. It's mysticism with math.
For it was my faith in you that lets us share the common delusion of our near instant world wide communication.
Re:Dark energy discovered 27 years ago?? (Score:5, Informative)
Uhm, is there any evidence that "space itself" is a thing that can be have anything "applied" to it? As if "space itself" is a physical entity?
In a sense, yes as it’s a direct result of general relativity and something we exploit as weak and strong lensing in astronomy measurements. Look at any deep James Webb photo, those stringy smeared galaxies are really normal looking but like an image seen over a very hot sidewalk and are wavy. Yet unobstructed photons only travel in a narrow straight line, they define straightnesses. Mass tells space how to bend and space tells mass how to move. We are boxed in by one large horizon on the outside by the propagation of causality at the Big Bang and by numerous horizons around mass singularities that bend spacetime past the speed of causality. These not only squeeze space as viewed as light rays from outside, but fundamentally change the nature of space and time across the boundary as we extrapolate from our understanding on this side
How does anything apply "pressure" to "space"? Is space made of particles? Waves? Energy? But as energy it should be particles or waves or something.
spacetime in modern physics is a series of infinite independent fields that have an excitement energy possible at every point. Particles are a collection of stable excitations. Pressure is an analogy, but if you correctly write in the formula for positive energy you can easily add a negative energy term, which would cause space to expand rather than contract like we see lensing examples do. This term looks like what the missing piece of our understanding is, because we are measuring an accelerating expansion at the moment. Spacetime is written that way because in the explanation you want they are both integral but it
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Mass tells space how to bend and space tells mass how to move.
I see you've read my sig.
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Wheeler, isn't it?
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I've had that sig so long, I'd forgotten where I'd seen it, but apparently, yes. It's Wheeler.
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Re:Dark energy discovered 27 years ago?? (Score:4, Insightful)
Yeah, but what is the certainty? I'd ask for error bars, but that doesn't directly apply to a theory.
There is, indeed, evidence that the universe used to be expanding quite rapdily, but "inflaton" particles feel quite ad hoc, and thus not to be trusted. And while the expansion theory is consistent will all the evidence, I'm not sure what the error bars are on a lot of those measurements. Perhaps it tends to expand sinusoidally, or even at random times and places...how would you test? Different groups using different measures have come up with different answers as to the rate/consistency of the expansion. This makes me feel that any strong belief in any explanation is probably at best premature.
In fact, I believe that any universal rate of expansion is incompatible with general relativity. Not only would it need to vary with the density of the matter locally, but it seems to require a universal frame of reference.
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That step needs expansion or considerable clarification. Your reticence ("seems to") suggests that you agree.
If the expansion rate is a function of elapsed time since [Big Bang / end-of inflation / breaking of the Higgs symmetry/ whatever], then each local area would react similarly (without requiring long-distance communication - a not-very-hidden "hidden variable") without requiring either a univ
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A hypothesis for which no test is feasible ... there are discussions about that sort of concept in Popper et al over the decades. But a workable description of such ideas is "useless". Personally, I think, with similar support, that it's invisible pink lizard-aliens moving the interferometer legs.
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Dark Energy is the name for the phenomenon an accelerated expansion of the Universe. This was measured by observing distance and velocity of distant supernova, and later also with other techniques (galaxy clusters for exampl). Dark Energy is the additional energy available for driving this, which is not accounted for in light-emitting baryons.
What causes the Dark Energy is another question, and that, indeed, has not been solved ("proven") to date.
With the recent proposed theories that time doesn't move the same everywhere in the universe, and in fact slows down or speeds up based on the amount of matter in a given area, it's starting to look like what we thought was expansion may actually just be a large void space surrounding the closest galaxies to us. Lots of recent observations, observations not possible until the larger space-based telescopes started probing objects billions of lightyears away, are making it seem like astrophysics is about to h
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Dark Energy is the name for the phenomenon an accelerated expansion of the Universe. This was measured by observing distance and velocity of distant supernova, and later also with other techniques (galaxy clusters for exampl). Dark Energy is the additional energy available for driving this, which is not accounted for in light-emitting baryons.
What causes the Dark Energy is another question, and that, indeed, has not been solved ("proven") to date.
With the recent proposed theories that time doesn't move the same everywhere in the universe, and in fact slows down or speeds up based on the amount of matter in a given area, it's starting to look like what we thought was expansion may actually just be a large void space surrounding the closest galaxies to us. Lots of recent observations, observations not possible until the larger space-based telescopes started probing objects billions of lightyears away, are making it seem like astrophysics is about to have a truly generational ground-shift in some of the long-assumed resolved theories.
Close, this is proposed to close the discrepancy in measurement of expansion from big bang conditions like the microwave background and astronomical measurements with things like type 1a supernova. So it might mean 68 km/s/Mparsec or 73 km/s/Mparsec but everything we have points to about 7 and not 0.
Re:Dark energy discovered 27 years ago?? (Score:5, Informative)
here has never been any proof that dark energy actually exists,
By definition. "Dark Energy" is like Terra Incognita, or "10th Planet".
It is a placeholder for something hypothesised, but not yet discovered.
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"Dark Energy" is like Terra Incognita, or "10th Planet".
No, that's Dark Matter.
Re:Dark energy discovered 27 years ago?? (Score:4, Informative)
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It's not just throughout *this* galaxy, but throughout almost every galaxy for which a rotation speed (profile) can be measured, and also individual galaxies orbiting in galactic clusters. It's not just the one case, but many observations.
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... but for which substantial evidence has been claimed.
The challenge of this paper is that, in effect, it is saying "that evidence (interpreted as support for Dark Energy) is actually non-existent because the observations are a consequence of mis-reading progenitor-star ages, which changes the modelled SN brightnesses.
Re:Dark energy discovered 27 years ago?? (Score:5, Insightful)
Dark Energy , and Dark Matter, aren't really theories in the sense we usually use in science. They are placeholders to describe missing variables in the math used to describe gravitational behavior as it deviates from the otherwise highly reliable Einsteinian and Newtonian accounts for it.
Dark Matter, because the maths and observations seem to show a *lot* more mass in galaxies than we can account for.
And Dark Energy, because something appears to be accelerating expansion, and basic physics tells us that if something is accelerating, theres a force being applied *somehow*.
But we dont know what that missing mass in galaxies, or the missing energy in expansion, is, so its "Dark". Its not a conjecture, or a theory, its literally scientists saying "We dont know whats going on here".
And you cant disprove that, because your trying to disprove that scientists dont know whats happening. But most assuredly they dont know whats happening, and THAT is what Dark Energy literally is. The giant question mark surrounding a fudge factor in the maths.
Re:Dark energy discovered 27 years ago?? (Score:5, Insightful)
Re:Dark energy discovered 27 years ago?? (Score:5, Interesting)
I think "yes, they make those things up" is overstating the situation and contributes to the sort of complaining you describe.
Imagine a scenario where you're standing across the room from a small paper bag on a scale. Confusingly the paper bag, which you'd think would only weigh a few grams, in reality comes in at 10kg. I don't think it's fair to say that I'd be "making up" anything if I theorize that there are massive objects in the bag that I can't see, and based on things like the size of the bag put some constraints on what those objects might be. It's formulating an explanation for empirical data based on our understanding of the physical laws of the universe.
I think that's a reasonable analogue for the current understanding of dark matter. We haven't figured out how to "open the bag" and say what particles or mechanisms are responsible, but it's not just a fudge factor in the models either.
Disclaimer: I'm going on an undergraduate physics degree and a casual interest in the subject.
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I don't know if "real" scientists would agree with your analogy, but it makes sense to me (with less qualification than you, but like you, have a casual interest). I might well use this explanation with my kids, which will do them for the next several years at least. Thanks :-)
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Einer Expansion von 500 km/sek pro Million Parseks entspricht nach EINSTEIN und DE SITTER eine mittlere Dichte von rho = 10^-28 gr/cm^3. Aus den Beobachtungen an selbstleuchtender Materie schätzt HUBBLE rho ~ 10^-31 gr/cm^3. Es ist natürlich möglich, dass leuchtende plus dunkle (kalte) Materie zusammengenommen eine bedeutend höhere Dichte ergeben, und der Wert rho ~ 10^28 gr/cm^3 erscheint daher nicht unvernünftig.
Helvetica Physica Acta, Vol. 6, p. 122
An expansion rate of 500 kilometers per second per million parsecs is equivalent to an average density of rho = 10^28 grams per cm^3, according to EINSTEIN and DE SITTER. From the observation of self radiating matter HUBBLE estimates rho ~ 10^31 grams per cm^3. Of course, it is possible, that radiating plus dark (cold) matter put together result in a massively larg
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Everybody bitching about it should just be sent a copy of We Have No Idea [goodreads.com]. That pretty much summarizes how little we actually know about the universe, and how much we have yet to learn. And it's a damn fun read on top of it.
Re:Dark energy discovered 27 years ago?? (Score:4, Insightful)
Just a name for a phenomenon. We call whatever's causing it "dark energy". Nobody's claiming it's a definitive, rigorous explanation. Until we know better, it's as good a name as any.
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As far as you know.
Edwin Hubble has discovered that galaxies that are further away are redshifted more, which is odd because one would expect gravitational blueshift.
This correlation between redshift and distance is called the Hubble constant.
One interpretation is that these galaxies are moving away (and that the redshift is a Doppler shift), but that doesn't make sense because at a sufficiently large distance, they appear to be moving away faster than light, and also everything is moving away from everythi
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So you are taking the easy way out, the Ignoramus Ignorabimus.
Re:N. Tesla is more relevant than ever: (Score:5, Insightful)
Special relativity models constant lightspeed pretty well, general relativity models gravitational lensing pretty well and builds on the former. Those can be experimented with on earth or with observations near the sun in the sky, you don't need any three degrees of separation cosmology.
Re: N. Tesla is more relevant than ever: (Score:4, Interesting)
Did epicyclism predict better tha Aristarchus's contemporaneous heliocentric theory, because the Greeks lacked the imagination to think that stars could be far enough away that their parallax was too small for their instruments to measure? So was the real problem lack of imagination?
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If it did, I'd guess Aristarchus didn't account for Jupiter's effects.
FWIW, epicycles can match Newton's math for accurate predictions, it just gets a lot more complicated. And isn't as theoretically elegant. (I'm not sure it couldn't be made to handle the deviation of Mercury's orbit. It's quite good at ad hoc adjustments.)
Re: N. Tesla is more relevant than ever: (Score:2)
How do we know current physics is not predicting well enough that we allow scientists to make stuff up, as epicyclists made stuff up about planets orbiting in circles because circles are more elegant?
All theoretical. (Score:1)
All of these news can be summed up by; "My source is that I made it the F@#& up".
Negative Dark Energy, WTF? (Score:3)
Re: Negative Dark Energy, WTF? (Score:2)
How can dark matter account for dark energy? Dark matter generates gravity while dark energy pushes matter apart. Wouldn't more dark matter require more dark energy to accommodate?
turtles all the way ... (Score:3)
Dark matter generates gravity while dark energy pushes matter apart. Wouldn't more dark matter require more dark energy to accommodate?
dark energy also generates gravity. it's actually zillions of giant space turtles amassed in a colossal expanding dyson sphere enclosing the entire observable universe. they're eating away all the ether and mating and reproducing on their way, pooing for thrust and dragging everything with them. dark matter is just ejected turtle poop left behind. their gravitational pull is a function of their density fluctuating with expansion and mating periods, defined by the turtle horniness coefficient, the cosmologic
Re:Negative Dark Energy, WTF? (Score:5, Informative)
Dark energy and dark matter were not "invented". And any physicist worth his/her/its salt will tell you that. For the umpteenth time (and read the responses above), dark energy and dark matter are merely place holders in equations that say, "something goes in here but these are the properties it must fulfill to earn its place in place of these place holders." Why is that so difficult for you to understand?
Re: Negative Dark Energy, WTF? (Score:2)
Is it hard to understand that it's hard to understand why the properties it must fulfill violate all the principles of physical common sense that have been drilled into us, religiously?
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Re: Negative Dark Energy, WTF? (Score:2)
If F=ma doesn't work at quantum or galactic scales, can I question if it really works the way we think at our scale, or have we gone and hallucinated a zero-sum physics like epicyclists built a theory on the concept that circles are perfect therefore planets must orbit in circles?
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Seems like a swag based on a swag.
Everything seems like swag based on swage when one theory contradicts another. Eventually you end up somewhere correct. This is how science works. Things are tested, postulated, replicated, and if needed, abandoned.
If dark energy is either proven wrong, or postulated as being less likely to be correct then a better theory then it will go the way of Aether https://en.wikipedia.org/wiki/... [wikipedia.org] Give science time. We've taken many generations to get here, the "correct" answer may not come in your lifetime either.
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Dark energy isn't a theory, it's just a name. A name for "something with these particular properties". My quibble is that those properties don't seem reasonable. We can't measure the expansion of the universe with one number if it's not expanding the same rate everywhere, and it shouldn't be. Also the measured rate of expansion is ... well, it has pretty large error bars, because our ways of judging distance aren't that precise. And don't always agree. And our ways of measuring expansion depend on spa
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Dark energy isn't a theory, it's just a name. A name for "something with these particular properties". My quibble is that those properties don't seem reasonable.
Does the ability to quantum tunnel seem like a "reasonable" property of protons? That they can pass through an impassable barrier because some tiny portion of their wavefunction seeps through to the other side of it?
Physics is weird, man.
The big crunch (Score:3)
how different from a "big crunch" is a black hole?
Re: The big crunch (Score:2)
A big crunch very well may create a black hole. But they are orthogonal concepts.
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What would it be a hole in?
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Space-time.
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how different from a "big crunch" is a black hole?
It is a matter of time and space. If you are inside a supermassive black hole, you have at best days to live. Outside, you have many billions of years.
Sure, the result is the same, but I have a preference.
In both cases, all world-lines converge. One space-like and local, one time-like and universal. For a better answer, the maths is beyond my comprehension horizon.
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A black hole is an object of some kind that exist in "normal" space, whatever that is.
Depending on which philosophical interpretation of gravity you embrace, it either has a "singularity" inside it, which exists because its gravity distorts the space around it (and the sticks you measure it with) to some infinity; or a real object, which looks "distorted" to you because you perceive it with sticks that are distorted by its gravity.
The difference to you is nil, though, because outside of some fringe issues (
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IIUC, it doesn't actually have a singularity, it will just eventually have one after an infinite amount of time (as measured from outside). And when the singularity happens the laws of physics break down...so nobody know what it looks like from the inside. But the precursors to the appearance of the singularity are such that there won't be any observers, even in the Quantum Mechanics sense of observer.
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of course there's no singularity, singularities are nonphysical. they just tell us we don't know what's going on.
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Sorry, but a sawtooth wave is full of singularities, not that we can generate a true sawtooth wave, but singularity doesn't tell us we don't know what's going on. You need a larger context to know if and what it means. IIUC Hawking believed that the black hole singularity would never actually be reached, even on an internal frame of reference...that uncertainty would prevent that from happening. A singularity just means that the projection you're making stops working. If we're talking about the space-ti
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a sawtooth wave is full of singularities, not that we can generate a true sawtooth wave, but
See what I mean by "nonphysical"?
IIUC Hawking believed
Hawking was a mathematician, he didn't care much about physics. But he was smart enough to mask that by writing math jokes on topics that he thought would defy experiments for many years, or never, like his unverifiable hypotheses about "black hole radiation" or his other meaningless phase space transformation games, which were actually done by his students.
Incidentally, I heard in a conference once about a side result of an otherwise failed experiment which, IIRC puts a sol
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I don't think there's anything that absolutely precludes an "observer".
But there is something that absolutely precludes any observer from communicating to anywhere outside the black hole's event horizon. That is what "event horizon" means : events the other side of it cannot be observed.
Which is why there are occasional fusses over rotating (+/- small, primordial) black holes - some arguments on general relativistic frame dragging get used to "expose" the black hole's central singularity without a masking e
Investment advice needed (Score:4, Funny)
Re:Investment advice needed (Score:5, Funny)
Try investing in land in Florida. Now that la Presidenta has canceled global warming with a swish of his Sharpie, it is safe to put all your money in there. Better yet, buy an acre in Florida, excavate a reasonable sized hole, and dump your money in. If you cover it up real fast no one will know where you hid it. You don't even have to worry about hurricanes now due to la Presidenta's Sharpie Woo.
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Not in fossil fuels; with the universe easing off the throttle the demand for energy is bound to be less.
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But the demand for petrochemicals as chemical feedstocks will continue.
We might not burn the stuff, but we'll continue to want to put it into chemical plants because it's cheaper than making long hydrocarbon chains ourselves.
Until someone manages to commercialise algae-catalysed CO2 -> long chains reactions. Which without the fuel market, is not so attractive an investment.
Re: Investment advice needed (Score:1)
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Have you stopped believing in the Expanding Earth?
When did you accept the reality of tectonic subduction? Before or after you became a FLERFer? And have you stopped hitting your wife with your dog yet?
TACOverse (Score:1)
Maybe its variable: acceleration starts, stops, reverses, rinse, repeat...
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Go and revise your non-Euclidian geometry. You clearly failed that exam.
It is possible for the universe to be finite in 3-dimensional extent, and unbounded.