Dark Energy May Be Changing

SpaceAdmiral writes "Nature is reporting that Dark energy, the hypothetical energy driving the universe's expansion, may not be as constant as previously thought. According to new research the strength of dark energy may be very different now than it was when the universe was young."

Comments

That's a pretty bold statement...

[numLocked]

...considering no one even knows if dark energy EXISTS.

Re:That's a pretty bold statement...

[rodac]

I personally always saw "ether" more as an engineering theory to provide a useful engineering tool instead of a scientific theory but that is more an academical point.

I find it disturbing that the Physics community allow these sub fields to still call themself "science" when they have nothing at all to do with real science and only results in dilluting the value of real/hard science. I say this as a mathematician, the only remaining hard science.
I mean where is the scientific methods, where are the scientific proofs? All i see are more or less accurate theories, hypothesis and models that when proven wrong are mended by another non-provable bandaid theories.

The problem is that using theories, that are just theories and not provably correct means that people will build a framework of other theories ontop of it and when/if the original theory is proven wrong you can not just discard the theory since the cost of doing so (invalidating another huge number of other theories built ontop of it) is just too great.
This is a trap that several fields in physics have fallen into and they are paying the price for now by having to invent more and more unprovable theories and explanations in order to keep it all together and semi-consistent.
I.e they have little option than to try to mend the breakage since discarding the theory would bee too expensive.
This IS a tragedy for physics!

In hard science/math we do not yet have that problem since we still try to be stringent and keep the science in good health by completely discarding and disallowing anything that can not be formally proven true.

Re:That's a pretty bold statement...

[Metasquares]

Just like the "luminiferous ether" was "necessary" 100 years ago because it was assumed that light couldn't possibly travel in a vacuum?

I always cringe when I hear physicists talk about dark {matter|energy}. Finding new data on dark matter is like claiming that the invisible pink unicorn is actually purple.

Re:That's a pretty bold statement...

[thesandtiger]

They are only "required" if one insists that current theories are correct and complete.

Kind of like aether was "required." And phlogistion. And igneous fluid.

I'm not saying that dark matter and dark energy don't exist - I don't know, and neither does anyone else - but I am saying that they're not necessarily "required."

Re:That's a pretty bold statement...

[gutnor]

I guess it is obvious that there are some flaw at some level in our understanding of the universe.
It is even so obvious that in order to make the measures stick to the theory, we need to introduce 'patches' that have well known properties, but unknown 'physical' representation like the dark matter and dark energy.

That the way science works. Before having an absolute correct theory we still need any theory to start with, demontrates and experiment and maybe change it or even replace it later. It is easier to start with a theory we are more or less confident with ( by experimentation ) and patch it to make some progress than throw everything away and start from scratch.

Maybe in x years some guy(s) will find that 3 stars in a line of 100 lightyears produce the same effect as if there was an amount y of dark matter. And this guy will be able to demonstrate his theory because thanks to a patched theory during the previous x years, scientists have been able to measure very precisely the characteristic of this dark matter and are able to validate his results!

Now of course, I said 'start with a theory we are more or less confident with' and that's where people starts disagreeing...

Re:That's a pretty bold statement...

[selfsealingstembolt]

Sigh. Ok, let's try this.

Mathematics is not science. It is a very complex formal system. You could desribe it as the science of understanding that system, I guess. But I wouldn't. Although you are right, mathematics is somewhat purer, that does not invalidate physics. For example: Let assume we have a theory of space, time and gravity, that seems to be tremendously correct for all observations we made as of now (note that this is just an example, we do not have such a theory, but please bear with me). Now we observe some new event or something that was out of reach previously, which cannot be described with current theory, and seems to need not a small fix, but a complete rework of current theory. So, does this observation suddenly invalidate the usefulness of the existing body of theory? Does an apple on earth suddenly not fall with the same speed as before and does it not release the same amount of kinetic energy in impact?

What physics is about is one belief: That the world can be described in terms of a formal system (mathematics). That is the only 'faith' physicists have. We don't know (and probably never will) if that is true or not. All we know is that everything in nature that follows rules can be described with a formal system and if there is something that does not follow a set of rules, it cannot be predicted anyways.
Besides that, physics is just trying to find new insights and new systems to describe rule-abiding reality as accurate as possible, using mathematics as a tool. Physics does acknowledge, that it may never be complete. But the knowlege we have gained so far is correct and works, albeit only for the cases in which it has been tested. And no new insight will invalidate that. No machines will stop working, no buildings collapse, because of a new observation that cannot be described within the current body of theory. We may find a better, simpler or more complex theory, which gives for tested known and understood cases the same results as the old one AND describes previously unexplainable observations.

And if you want to start with "formally proveable", may I give you Gödel? Any system complex enough to reference itself (like mathematics) is by definition incomplete AND contains provably unprovable sentences which are nonetheless valid within this system.

Re:That's a pretty bold statement...

[endoplasmicMessenger]

All of this is pretty well supported by the best current observational evidence, although the physical nature of dark matter and dark energy are both poorly understood

Physicists were once certain that "ether" existed. It was a construct that was necessary in order to make sense of many observations that were being made.

It turns out they were wrong. Ether does not exist. Ether was a construct that had nothing to do with reality even though it had some explanitory power.

That the construct of Dark Energy explains some observations does imply that it has anything to do with reality.

Re:That's a pretty bold statement...

[jackbird]

Actually, the ancient Greeks knew the world was round, and made a pretty good stab at measuring it based on simultaneous observations around the mediterranean basin.

Later on, pretty much anybody dealing with sailing ships noticed that the mast came over the horizon before the rest of the ship did. It was the church, with its insistence on the literal veracity of biblical statements about the world, and its stranglehold on political power throughout Europe, that made the Earth's shape a dangerous topic to shout from the rooftops.

For a modern analogue, biology, rather than cosmology, would seem to be the place to look.

Re:That's a pretty bold statement...

[ceoyoyo]

Something is required. We use "dark matter" and "dark energy" as placeholders for that something. The names themselves are vague and describe the properties of the thing. Eventually, hopefully, we'll discover what these actually are (whether physical reality or modifications in a theory) and we can give them better names.

Aether was a perfectly reasonable hypothesis that made certain predictions that turned out not to be true and so was replaced when something better came along. This story is showing the same kind of work. From the article, one hypothesis is that the thing we call "dark energy" is the effect of quantum foam. Apparently that implies that the dark energy effect would be constant over time. These preliminary observations indicate that might not be the case. If they prove to be true, the quantum foam hypothesis will be disproved.

Re:That's a pretty bold statement...

[ceoyoyo]

Exactly. There was no mechanism known at the beginning of the 20th century to explain how a wave could travel in a vacuum. There was plenty of observational evidence showing that waves CAN NOT travel in vacuum. In fact, none of the waves we were familiar with travel without a medium. So, if light is a wave, then it probably needs a medium to travel in. Let's call it luminiferous aether. Now, what properties will it have? Can we measure them? Thus the Michealson-Morely experiment, which disproved the hypothesis. So we kept at it and the new theory is that light isn't really a wave like we're familiar with, so it doesn't need a medium to travel through.

Aether is a SUCCESS story of science done right. Dark matter/energy is the same. They are anomalies which we cannot explain. We're investigating their properties and various mechanisms have been and are being proposed for them. We have to gather observations, like this article is describing, to be able to choose between these hypotheses.

How would you have cosmologists proceed?

Re:That's a pretty bold statement...

[Anonymous Coward]

Actually, still no. The church never failed to recognize a round earth, nor did any major government.

Columbus was laughed out of the Italian court for proposing a trip the long way around to India, hoping that the mathematicians were all wrong somehow. He was denied because he planned to pack too few supplies; this was true, when he later recieved funding from the Spanish, he ran out of supplies just before landing in the East Indies, less than half way to India.

The myth that people ever thought the earth was flat was invented by a popular American storyteller to try to make Columbus out to be some sort of hero, when in fact history shows us that he was a pirate and a rapist.

A stretch

[Da3vid]

I personally hate this whole dark energy thing. Its always this and that, here and there. It seems to me to be a poor attempt at a unified theory. Its trying to bring everything together into one thing and to account for all the oddities out there, but is this really any better than the Greeks accounting for oddities in terms of gods and goddesses? It seems to me that we are only adding increased complexity into an already complex system and we are not significantly increasing our understanding. What we are increasing is more unlikely system. Often, the most simple answer is the correct answer. I can't wait for the next new scientific revolution and the next paradigm shift. I'm bored of this one.

-Da3vid-

article wasn't very clear, but...

[heatdeath]

So...brighter means closer. Since that was the result that prompted us to think that the universe is expanding in the first place, I guess this means that the rate at which the universe is accelerating is accelerating.

http://en.wikipedia.org/wiki/Big_RipBig Rip.

Re:Not THAT again...

[helioquake]

matter != energy.

Well, in this particular term that is.

I'm sure some nerds will bring in on Einstein reference that is E = mc^2.

Re:It is changing, but we don't know which way

[grimJester]

Since dark energy acts opposite to gravity, I'd assume more would mean brighter visible GRBs. Also, we have no good explanation for inflation. Could this be it? Speculating even further, if dark energy is weakening the universe might not expand forever.

IANAP but...

[Goalie_Ca]

According to new research the strength of dark energy may be very different now than it was when the universe was young.

Maybe its just the engineer in me, but isn't it possible that we're just observing some other unknown effect. Something so complicated and exotic doesn't feel right. When it comes down to the math we juggle equations around, fit curves, and re-evaluate until the math yields a good approximation. Math juggling is one thing but I don't think there's a strong case for creating a physical entity for it.

Re:String Theory Fallout

[crotherm]

Face it, we dont't what makes the universe expand/contract. We really don't know shite. All we can do is attempt to observe, and propose theories on those observations and try to falsify them. As we learn more, invent/discover better methods and devices for measurements, our understanding will evolve. I know this is basic stuff, but it seems many folks are forgetting this. We are mear children in our understanding of our universe.

Dark Matter/Dark Energy is a kludge

[kcbrown]

I don't know about you, but this whole dark matter/dark energy thing looks, sounds, and feels like a kludge to me.

It's almost as if the people who are proposing these explanations aren't willing to toss out the current explanations they have for things and essentially start from scratch. But when you start to kludge explanations together as they have with dark matter/energy, that's exactly what you should do: go back to the drawing board. Having to kludge something is a huge hint that you got something badly wrong somewhere way back towards the beginning.

Obviously whatever you come up with has to explain current observations to at least the degree that current conventional theories do, and current theories then have to become a "special case" of the more general theory, just as newtonian mechanics is a special case of relativity.