New Physics? Fundamental Cosmic Constant Now Seems Shifty

[Temujin]

New Physics? Fundamental Cosmic Constant Now Seems Shifty
By Clara Moskowitz
SPACE.com Senior Writer
posted: 14 September 2010 10:32 pm ET

A fundamental constant of the universe may not be so constant after all, according to a new study.

Recent observations of distant galaxies suggest that the strength of the electromagnetic force – the so-called fine-structure constant – actually varies throughout the universe. In one direction, the constant seemed to grow larger the farther astronomers looked; in another direction the constant took on smaller values with greater distance.

If confirmed, this revelation could reshape physicists' understanding of cosmology from the ground up. It may even help solve a major conundrum: Why are all the constants of nature perfectly tuned for life to exist?

"This is an exciting and potentially important result that challenges astronomers and particle physicists for an explanation," said astrophysicist John Barrow of the University of Cambridge, who was not involved in the new study but has worked with the researchers in the past. "It could be a further hint about new physics."

A changing constant

Astrophysicists have been studying the fine-structure constant – known as the alpha constant – for years, searching for hints that it might change. Some projects have found evidence that the constant does vary, while other probes confirmed the constant's constancy.

But the evidence supporting the alpha constant's variable nature was ambiguous, because it could also be due to a variation over time, or across different parts of space, researchers said.

The farther out astronomers peer into the universe, the longer it has taken the light they see to reach Earth. Since this light is older, it represents an earlier epoch in the universe's history.

So if scientists measured a change in the fine-structure constant from different observations, it may have been because the constant has different values in different places, or it might have been because it had different values at different times. But determining which case is right has been a challenge.

To settle that question, researchers led by John Webb from the University of New South Wales, Australia, gathered observations from the Keck telescope in Hawaii, and the Very Large Telescope in Chile – thereby covering both the northern and southern skies.

"When you look in one direction, you cannot distinguish between variation in space and variation in time," co-researcher Victor Flambaum, also of the University of New South Wales, told SPACE.com. "Now there is nearly complete coverage of the sky. The conclusion is:It's a variation in space, not in time."

To determine how strong the alpha constant was in any given spot, the scientists measured the frequency at which electrons in various atoms would hop from one energy level to the next. This frequency depends on the fine-structure constant.

The researchers found that in the northern sky, the fine-structure constant gets smaller with increasing distance, or as astronomers look farther back in time. In the southern sky, however, the alpha constant value appeared to increase the farther away they looked.

Since those two results would contradict each other if the alpha constant varied with time, the constant must take on different values in different areas of the universe, the researchers concluded.

Why do we exist?

Webb presented the findings last week at the Joint European and National Astronomy Meeting in Lisbon, Portugal. The research has been submitted to the journal Physical Review Letters and is awaiting peer review.

If the study is confirmed, it could be a landmark find in astrophysics, researchers said.

"I find this result quite exciting," said Steve Lamoreaux, a physicist at Yale University who was not involved in the study. "It explains the apparent discrepancy between different analyses done the last few years.

"Of course, the result needs to be independently verified," he added.

Flambaum said he was particularly interested in what the result could tell scientists about the origin of life.

"This is a puzzle which has existed for many years," he told SPACE.com. "A minor variation of the fundamental constants forbids life to appear – we just could not exist."

For Flambaum and others, it seemed like too much of a coincidence that the universe's constants – which includes the alpha constant and others like the value of the strength of gravity, or the strength of the strong interaction that binds atomic nuclei together – should be perfect for building stars and planets and life.

"Now we have an explanation," Flambaum said."If fundamental constants vary in space, we just appear in the area of the universe where constants are good for us."

In other regions of the universe where the constants are different, life may be absent, he said.

Making sure

Flambaum admitted that such revolutionary results need even more evidence to be believed for sure.

And other experts may take some convincing.

Helge Kragh, a science historian at the University of Aarhus, Denmark, who has written about the history of the fine-structure constant, said it's important to "keep a healthy skepticism" about announcements like these, since past measurements of variation, such as earlier claims that the constant changes over time, have later been disproven.

"If history is a guide -- and often it is not -- the results of Webb et al. will turn out to be untenable," he said.

Flambaum said the team plans to collect more data from the distant universe, as well as conduct laboratory experiments, to test their results.

"The problem is whether there are systematic biases which the authors have not thought of which can mimic the appearance of varying alpha," Barrow said. "They are a very strong and experienced observational team who have subjected the data to many tests in the search for bias but have failed to find any so far."

I have to say I'm skeptical. The one thing you often here from scientists is that the laws of physics are the same through out the universe (other universes, all bets are off).

[Aranfan]

I wonder if this ties into the recent muonic measurement of Proton radius that differed by 5 standard deviations from the electron measurements thereof.

[Wyrm]

I'd love to see the peer review literature about this.

[PaperJack]

If confirmed, this revelation could reshape physicists' understanding of cosmology from the ground up. It may even help solve a major conundrum: Why are all the constants of nature perfectly tuned for life to exist?

Wut wut wut
Life is the one perfectly tuned to the costants of nature, not the other way around

[Molyneux]

This is interesting. If it can vary between different areas, maybe it's governed by another physical law - something that would let us predict how and when the "constant" might vary.

[Kanastrous]

If confirmed, this revelation could reshape physicists' understanding of cosmology from the ground up. It may even help solve a major conundrum: Why are all the constants of nature perfectly tuned for life to exist?

Wut wut wut
Life is the one perfectly tuned to the costants of nature, not the other way around

Well...yes and no. In order to allow for the development of life like us, a series of physical constants (laws) are required to have certain values. Too much of this, and galaxies don't form; too little of that and electrons spiral into protons and there's no matter suitable for making anything (yes, obvious grotesque over-simplification, but...)

So a question is, why did this universe start with those particular constants, leaving the possibility for us to be here, rather than one of a very large set of other possible constants that would *not* have permitted us to be here?

So yeah, life has to exist within the constraints of what can be done with matter and energy, to make it but at the same time the nature of matter and energy have to be in a narrow subset of a great many possible arbitrary starting values for the possibility of our kind of life to even exist.

For my part the multiple-universes concept seems to work the best; the more universes there are the greater and greater the odds that at least one will be suitably constituted for life like us.

But since I'm not a physicist of any particular sort that's all open to correction.

[Simon_Jester]

So a question is, why did this universe start with those particular constants, leaving the possibility for us to be here, rather than one of a very large set of other possible constants that would *not* have permitted us to be here?

Why not?

This argument has always struck me as like an acorn in a forest looking up and wondering "But why does there happen to have been an oak tree here for me to fall from, instead of a completely different tree?" It's a huge reversal of priorities: there are lots of places out there with no oak trees and no acorns, so it's hardly a deep question about nature to ask, upon seeing an acorn, "but why is there an oak tree here?"

There's nothing magic about oak trees; they just happen to exist in some places and not in others. Even if the odds of an oak tree appearing in a particular spot were billions to one, it would be absurd for acorns to ask "why were we so lucky as to have an oak tree here?" Because the answer is always the same: "if you weren't, then you would be in no position to ask the question."

[Kanastrous]

I can't answer that myself as I lack the expertise to frame a meaningful answer.* The fact that very intelligent people with a great deal of specialized knowledge in the relevant areas of physics are still inclined to ask 'why' and not content themselves with 'why not?' suggests that at the very least playing with the question is an entertaining way to pass the time.

I mean, for my own part I stick with the formulation proposed by that great physicist and moral philosopher, George Carlin:

"Why am I here?!"

"Plastic, asshole."

I don't know how well the oak tree analogy really works because the acorn could have fallen from a great many oak trees that all share the qualities required to produce and drop acorns, while at least going by Hawking et all's ideas only a very small subset of the possible initial states of this universe could have permitted our development.


* and in my personal philosophy - the the degree it can be dignified with words like 'philosophy' - why? is not a meaningful question in this context and not something I personally expend much time pondering.

[Consumerist]

Are the changes in the constant enough to kill any pre-existing living lifeforms? If so that would be quite worrisome.

[Steel]

So a question is, why did this universe start with those particular constants, leaving the possibility for us to be here, rather than one of a very large set of other possible constants that would *not* have permitted us to be here?

Why not?

This argument has always struck me as like an acorn in a forest looking up and wondering "But why does there happen to have been an oak tree here for me to fall from, instead of a completely different tree?" It's a huge reversal of priorities: there are lots of places out there with no oak trees and no acorns, so it's hardly a deep question about nature to ask, upon seeing an acorn, "but why is there an oak tree here?"

There's nothing magic about oak trees; they just happen to exist in some places and not in others. Even if the odds of an oak tree appearing in a particular spot were billions to one, it would be absurd for acorns to ask "why were we so lucky as to have an oak tree here?" Because the answer is always the same: "if you weren't, then you would be in no position to ask the question."

I never encountered the "Fine tuning Problem" phrased as asking why the constants are good for life, but as asking why the constants are what they are, because in strictly mathematical sense they're rather specific.

Take for example the curvature of the universe. This could have literally any value. There is nothing that says we have to live in a 'flat' universe, we could equally well live on the surface of a (hyper)sphere or in an open universe or anything in between. Measurements have in fact constrained us to be living in a universe that is essentially flat (+-2% experimental error).

Unfortunately the issue is that if you look at the density of the universe, you find that the density that corresponds to a flat universe is unstable over time as the universe expands (and expanding it certainly is). Any perturbation from flat at the time of the big bang would grow by a factor of 1050 by the present day, meaning that the universe would have have exactly the right density back then in order to be within our 2% margin today.

Now this isn't a deal breaker, it might be that we just have to accept the universe popped up perfectly flat and go with it. However, it would be nicer if we weren't actually so dependent on initial conditions. It turns out that if you have the theory of Inflation (which also neatly solves about a dozen other cosmological annoyances and is now quite widely accepted) this states that there was a period where the universe was undergoing exponential expansion for a period of time before the conventional big bang takes place. During this exponential expansion the density corresponding to a flat universe is an attractor, and so all initial conditions are pulled towards the flat state. Then once Inflation has got you very close to the fixed point after the big bang things proceed as normal and we end up with the universe as it looks now, but with the universe still very close to flat.

I've omitted all the actual maths, but the non GR version of this is quite easy for anyone to follow if you want to look it up.

The basic idea behind 'fine tuning' being is a problem is it assumes that things were somehow very special to begin with, and it is far more likely that actually we're in a stable state that most things tend towards due to due to a fundamental property of the universe.

[Chaotic Neutral]

I don't know how well the oak tree analogy really works because the acorn could have fallen from a great many oak trees that all share the qualities required to produce and drop acorns, while at least going by Hawking et all's ideas only a very small subset of the possible initial states of this universe could have permitted our development.

No,no,no, if the universe was different, you would say "Why is there a cactus here?" or "Why is there grass here?"

We are oak trees because oak trees are adapted to this universe.

And if there was no life you would say "........" or "Why is this black hole devoid of life?"

[Molyneux]

I don't know how well the oak tree analogy really works because the acorn could have fallen from a great many oak trees that all share the qualities required to produce and drop acorns, while at least going by Hawking et all's ideas only a very small subset of the possible initial states of this universe could have permitted our development.

No,no,no, if the universe was different, you would say "Why is there a cactus here?" or "Why is there grass here?"

We are oak trees because oak trees are adapted to this universe.

And if there was no life you would say "........" or "Why is this black hole devoid of life?"

The issue is that its very rarely a good idea to assume that we're exceptional. If we exist on a small planet orbiting a small yellow star, then it is reasonable to take as likely that small planets orbiting small yellow stars are probably relatively common - and in the case of human existence, if we exist as organic creatures in a complex environment, then it is reasonable to assume that this type of life is much more common than, say, Boltzmann brains. It's always possible that we beat incredible odds by existing in our current form, under these physical laws - but it makes more sense to assume, unless evidence indicates otherwise, that our existence is not incredibly unlikely, and attempt to figure out the "why" from there.