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...

[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...

[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.

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.