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Galaxy Clusters' Stunted Growth Confirms Dark Energy
A new study of 86 galaxy clusters in the early universe has provided independent confirmation of the existence of dark energy. In its absence, gravity's pull should have caused the number of clusters to increase by a factor of 50 over the last 5.5 billion years. What is observed is a factor of 10 increase. "Together with earlier observations... the new data strengthen the suspicion — but do not prove — that dark energy is a weird antigravity called the cosmological constant that was hypothesized and then abandoned by Albert Einstein as a 'blunder' almost a century ago. If that is true, the universe is fated to empty itself out eventually, and all but the Milky Way's closest neighbors will eventually be out of sight. ... Adam Riess of Johns Hopkins and the Space Telescope Science Institute, said: 'If this was a fox hunt and dark energy was the fox, I think they have closed off another escape route. But there is still a lot of terrain left for the fox, and we've seen little more than a glimmer of fur.'"
Galaxy Clusters' Stunted Growth Confirms Dark Energy
"Together with earlier observations... the new data strengthen the suspicion â" but do not prove â" that dark energy is a weird antigravity called the cosmological constant that was hypothesized and then abandoned by Albert Einstein as a 'blunder' almost a century ago.
Wait, what?
Hmmm, not sure if I follow, someone please correct me if I'm wrong, but it sounds like what he's saying is that if this were a highway chase and dark energy were a criminal's car, then they have placed a police car as a barracade in the way... but there's still a lot of exits around, and we've only seen a glimmer of chrome?
It's not dark energy, it's your mom!
If that is true, the universe is fated to empty itself out eventually, and all but the Milky Way's closest neighbors will eventually be out of sight.
Not only that, but depending upon the key value of state w, the ratio between dark energy pressure and its energy density, if the value of w is less than -1 then the universe will eventually be pulled apart as the rate of expansion begins to accelerate towards infinity. First the nearest galactic clusters will fade from view, then the nearest galaxies in our cluster, then the stars in our galaxy. Finally, approximately three months before the end, the solar system itself will become gravitationaly unbound, in the last minutes stars and planets will be torn apart, and finally, an instant before the end of everything individual atoms and their subatomic pieces will be ripped into ever smaller pieces until there is nothing left (i.e. the last bits just wink out of existence). The end, if it were to occur in this way, is around 50 billion years, or approximately 3.8 times the current known age of the universe, into the future. This hypothesis is known colloquially as the Big Rip.
(Sigh). Everytime I see a story about the cosmological constant I have to see the obligatory "that dark energy is a weird antigravity called the cosmological constant that was hypothesized and then abandoned by Albert Einstein as a 'blunder' almost a century ago." as if Einstein was so smart he predicted dark energy 100 years ago. No. He put a term in the equation to stabilize the universe, which was then thought to be static, against gravity. Then it turned out the universe wasn't static, it was expanding. That was the blunder. If there's an outward force, as there now seems to be, you'd put a term in the same place. But it's based on new data. I'm sick and tired of the "Aha! Einstein was right all along and he didn't even know it!" comment that has to be stuffed in every cosmological constant story these days.
You think that's air you're breathing now?
The part of logic that "necessitates" the existence of dark energy is inductive logic, which relies on inferences. Right now the evidence infers that dark matter exists, but as is the case with all inferences it could be wrong. Hence TFA stating that this discovery adds to the evidence but does not PROVE its existence (which would be deductive logic).
:( To quote from wikipedia
In either case dark matter may not be necessary at all. This is because in logic necessary has a hugely different meaning than the way you used it
* possible if and only if it is not necessarily false (regardless of whether it actually is true or false);
* necessary if and only if it is not possibly false;
* contingent if and only if it is actually true (and so possibly true) and not necessarily true.
So even if we can prove the existence of dark matter, we've only shown it to be contigent. We'd still have some heavy lifting to do to show that it cannot possibly NOT exist.
I KUT J00 M4NG!!!
For those interested the full paper is here. Apart from a couple of cosmological parameters they don't really improve previous estimates. It's still nice though that all the parameters agree very well with the previous (CMB + Supernova 1a) data with a completely independent method, hence the confirmation talk. I think though if there had been disagreement our understanding of clusters would have been blamed first. So in some senses this confirmed the current cluster models more than the cosmological constant, but that's not as 'sexy'!
So let me get this straight...we have Dark Matter because there's not enough gravity within a galaxy to explain the observations, and Dark Energy because there's too much gravity between galaxies to explain the observations.
Surely Occam's Razor comes into play here? Surely it's obviously simpler to say 'we've got the maths wrong for gravity beyond solar system scale' and start again at the chalkboard?
Business/App ideas are like arseholes: everyone's got one, they're mostly shit, but very rarely they contain a diamond
The summary makes it sound like they actually proved that dark matter exist, not simply added to the inference of it's existence :(
Science is not in the business of making provable claims. It's impossible to prove anything using the scientific method. Science makes falsifiable claims, and any experiment that fails to falsify them confirms the theory, but most certainly does not prove it. An experiment that "confirms" a theory is one that produces a result compatible with that theory under circumstances where a different result would have falsified it. Confirmation merely strengthens a theory, it cannot ever prove it.
"Convictions are more dangerous enemies of truth than lies."
Instead of proving the existence of Dark Energy, perhaps what this finding really does is prove that our models are wrong.
I often wonder if we're looking in the wrong place for an explanation...flaws in our cosmology sound more plausible to me than weird forms of matter and energy.
In that sort of model, the Hubble redshift is only proportional to the expansion ratio as a first approximation (whose range is roughly analogous to the range within the elastic limit of a spring).
There then becomes an upper limit to the possible size of the universe, that corresponds to the total (finite) massenergy contained within it. As we approach that limit, things unravel. The resulting increase in atomic instability can then be expressed as an effect of decreased nominal inertial mass due to the reduced background field strength (nuclear stability is a function of inertia).
But a decrease in local inertia also corresponds to an increase in the local rate of timeflow. The absolute end of the universe then represents a point in time where the nominal rate of timeflow is infinite (although, by then, there's nothing left to measure it with), so the period at which the universe nominally ends, measured in "insider-time", is in the infinitely far future. Okay, so its not quite infinitely far away, because the last proton evaporates at a finite time, but the timescale is effectively infinite to most intents and purposes, as far as we're concerned.
The advantage of this form of time-scaling is that it tidies up the Hartle-Hawking model - it allows the "equator" of the H-H bubble to represent the apparent end of the universe for insiders, and to be totally smooth. This removes the messiness that we'd otherwise tend to get when the bubble reaches its maximum size and parts of it start to contract. Contraction implies reversed entropic timeflow, so the HH bubble has a problem in that an observer living through the expansion-contraction region might see some mightily strange things going on. Some regions might be seen to be ageing in opposite directions to others. But if the interior rate of timeflow goes to infinity at the equator (as the angle of "proper" time approaches the angle of axial time, and its angle with the radial time-parameter 'a' tends to 90 degrees), then interior detail is totally erased at the equator, and the apparent inconsistencies with observerspace physics disappear ... you can never survive a transition past the equator, and the event-meshes of each hemisphere are isolated from each other by the equatorial evaporation zone.
The expansion and contraction phases of the bubble then both effectively belong to two separate universes, both of which think they're expanding, and both with opposite senses of proper time. The equatorial evaporation zone keeps both sets of causalities isolated, and prevents nasty messy phase transitions where the two "worlds" collide.
If we look at the geometry of one hemisphere of the extended H-H bubble model, and we use axial time as our reference, or we take a tangent to a given zone and extend that zone's local sense of proper time as as a straight line to give us our time-reference for the rest of the bubble, then what we end up with is a description that seems to describe a "Big Rip" at a definite, finite time. Our projection tells us that the universe contents speed up and start to "fizz and whizz" at an increasing rate before finally disappearing altogether. But to physics performed inside that universe, things aren't hotting up, they're cooling down -- instead of matter mysteriously evaporating after few billion years, it's decaying more conventionally over rather vaster timescales.
Cosmological timescales and reference systems
The thing one has to be careful o
Eric Baird
I honestly can't tell if you're incredibly insightful or just adding words after one another. My brain hurts either way.
It also interacts with the photons we can see. Otherwise, the refractive index of air would be exactly 1, instead of 1.00029
The Tao of math: The numbers you can count are not the real numbers.