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Variable fundamental constants

Sun, 12th Sep 2010

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Something which perplexes physicists is why the fundamental physical constants are what they are, why is the speed of the light about 300 000km/s, why is the charge on an electron 1.6 x 10-19C etc. and for that matter are they actually constant. This boils down to why does physics behave as it does, and is it the same everywhere?Artists concept of a quasar

The problem is that we can only do experiments to measure them precisely where we can get an experiment to - essentially just in our solar system. Otherwise we are limited to what we can observe. One fundamental constant we can observe very accurately is called the fine structure constant this is a combination of the charge of an electron, the plank constant and the speed of light, and measures how electric field and quantum mechanics interact to create energy levels in an atom. And it can be measured by looking at the spectra of atoms, so it is very convenient for astronomers.

Close to the earth this seems to be constant, but John Webb and collegues from the university of New South Wales have been looking at some of the most distant sources we can see quasars which are thought to be huge black holes accreting material billions of light years away. In 2003 they discovered that the fine structure constant appears to have increased about 1 part in 200 000 since the light left the quasars.

But this study was only done in the northern hemisphere, they have recently done a simlar study in the southern hemisphere using the Very Large Telescope in Chile, which has found something possibly even more interesting - the result was that to the south the fine structure constant was changing by about the same amount as you go back in time but it was decreasing rather than increasing.

They have found a fairly strong signal but only time and more experiments will tell if it continues to hold up. If it does it might explain why fundamental physics is so well suited to life, essentially because it varies throughout the universe and our form of life has only developed in the part of the universe where it can survive.



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Wait a minute! There's obviously some sort of scientific Three-card Monte going on 'ere. You're expecting me to say,
"Not blinking likely! How can they be constant if they vary then?"

Ho no! I'm not falling for that one.

I suppose I'll have to listen to the Podcast then. Geezer, Wed, 15th Sep 2010

They aren't constant, Geezer. For example the fine structure constant alpha is a running constant, and thus isn't actually constant, see NIST where you can read:

"Thus α depends upon the energy at which it is measured, increasing with increasing energy, and is considered an effective or running coupling constant. Indeed, due to e+e- and other vacuum polarization processes, at an energy corresponding to the mass of the W boson (approximately 81 GeV, equivalent to a distance of approximately 2 x 10^-18 m), α(mW) is approximately 1/128 compared with its zero-energy value of approximately 1/137. Thus the famous number 1/137 is not unique or especially fundamental."

Note that "varying with energy" also infers "varying with gravity", due to the spatial self-energy of a gravitational field. People have been talking about measuring alpha near the sun in solar-probe experiments for at least ten years now. See for example SpaceTime Mission: Clock Test of Relativity at Four Solar Radii. 

Note that alpha can be written α = e/2ε0hc. The e is "effective charge", but the electron has unit charge, the effect of which changes with the environment. Rework the expression using unit charge, and it's crystal clear that some other "fundamental constants" aren't constant either. Farsight, Wed, 15th Sep 2010

"a combination of the charge of an electron, the plank constant and the speed of light" So what exactly 'falls out of order' there, all three :) You sure? And was it the same type of discrepancy shown on both sides, decreasing in the southern hemisphere and raising in the northern? one part in 200 000 it seems, on both sides, and we in the middle :)

He*. We are the center of the universe :)


"The anthropic principle is a controversial explanation of why the fine-structure constant takes on the value it does: stable matter, and therefore life and intelligent beings, could not exist if its value were much different. For instance, were α to change by 4%, stellar fusion would not produce carbon, so that carbon-based life would be impossible. If α were > 0.1, stellar fusion would be impossible and no place in the universe would be warm enough for life."

yor_on, Thu, 16th Sep 2010

Even if our current theory's of redshift was incorrect the discrepancy would still exist, right? As a measurable imbalance. But it is based on measuring red-shifted waves from very far away if I get it right.

"The relative positions of wavenumbers, of atomic transitions detected at redshift, can be compared with laboratory values, via the relationship and the coefficient Q measures the sensitivity of a given transition to a change in alpha."

So how the heck do you get to this idea? And what could it mean?
Here's a very interesting explanation. 

And here is the paper (pdf) they put up. Evidence for spatial variation of the fine structure constant. yor_on, Thu, 16th Sep 2010

I've read that paper carefully, yor-on. It's good stuff. I also had a look at that interesting explanation, but it isn't so good. Charged particles don't actually exchange photons - people talk of virtual photons, but they're something different. As for the anthropic principle, that's junk science. There's no supporting evidence whatsoever, and it peddles the mythology of "fundamental constants", relying on people not knowing that alpha is a running constant. Hence we get this "big surprise" when Webb et al report cosmological variations in alpha. Farsight, Thu, 16th Sep 2010

To me photons are photons though :)
It's only 'times arrow' that seems to make the difference there, as described by the idea of what a Rindler observer might see.

The funny thing about all this is that we since the start of human history have had cults around light :)
Well, maybe they was right ::)) Maybe light is the ultimate 'thingie'.

One of them at least, 'time' seems quite important too.

And hey, 'Times arrow' huh :)
Now that wouldn't translate into 'frames of reference', would it? yor_on, Fri, 17th Sep 2010


But a running constant varies with energy with which it is associated (α varies logarithmically with the energy at which it is measured) - not the direction you are pointing your telescope; that's presumably a spatial variance (with other matters accounted for).  Just noticed you had already said some of this in your above post - oops!

this is a profound result if it is replicated - it threatens to challenge the EP and that's heavy stuff. 

imatfaal, Fri, 17th Sep 2010

Strictly speaking, imatfaal, the equivalence principle only applies in an infinitesimal region. Some say because of that, it doesn't apply at all. I take the view that it's a good principle and some minor infringement doesn't make it a bad principle. Standing on the surface of the earth still equates to accelerating through space even if you manage to spot some part-in-a-billion discrepancy. It's the same for Lorentz invariance. Some seem to want to say "Aha! The whole of relativity must be wrong!". IMHO it isn't, because relativity is full of first approximations anyway. Farsight, Fri, 17th Sep 2010

I will have to bow to your superior knowledge on this but GR is remarkably accurate for a theory that you say is crammed full of first order approximations. imatfaal, Fri, 17th Sep 2010

"Strictly speaking, imatfaal, the equivalence principle only applies in an infinitesimal region." I lost you there Farsight? Are you thinking of the equivalence between acceleration and gravity, or? And in what way is it applied only to infinitesimal regions?

To me it's one of the main rules we have in physics :) The equivalence principle

But you see the idea referred to in a lot of other 'equivalences' too, f.ex mass/energy, so maybe you are thinking of something else? yor_on, Sat, 18th Sep 2010

No, I'm talking about the equivalence principle we all know and love. There quite a lot of discussion of infinitesimal regions in the mathspages link you gave:

Have a read of Peter Brown's paper at for a different slant on it. If you're in a windowless room and you can feel "gravity", you might in fact be in a room in a spaceship accelerating through space. You can't tell the difference, hence the principle of equivalence. However if there's a room above yours, and another and another, you can tell the difference between being in a very tall tower and a very long spaceship.

Hmmn, maybe I could have put that better. Take a look at the last few pages of The Foundation of the General Theory of Relativity (3.6 Mbytes) for more on this.    Farsight, Sat, 18th Sep 2010

I'm still not sure what you meant Farsight? You wrote "Strictly speaking, imatfaal, the equivalence principle only applies in an infinitesimal region." And referring me to Kevin Brown that interpretation gets refuted by Einstein in that same paper?

Btw: Einstein wasn't that much for geometry.

-- -Quote-

" While relativistic mass is useful in the context of special relativity, it is rest mass that appears most often in the modern language of relativity, which centers on "invariant quantities" to build a geometrical description of relativity.  Geometrical objects are useful for unifying scenarios that can be described in different coordinate systems.  Because there are multiple ways of describing scenarios in relativity depending on which frame we are in, it is useful to focus on whatever invariance's we can find. This is, for example, one reason why vectors (i.e. arrows) are so useful in maths and physics; everyone can use the same arrow to express e.g. a velocity, (speed having a given direction) even though they might each quantify the arrow using different components because each observer is using different coordinates.  So the reason rest mass, rest length, and proper time find their way into the tensor language of relativity is that all observers agree on their values.  (These invariants then join with other quantities in relativity: thus, for example, the four-force acting on a body equals its rest mass times its four-acceleration.)  This is one reason why some physicists prefer to say that rest mass is the only way in which mass should be understood.

- -End of Quote ----


It may be interesting to note here that this geometric notion of describing
SpaceTime wasn't entirely shared by Einstein.

- - - -

Quoted from John D. Norton
Department of History and Philosophy of Science
and Center for Philosophy of Science
University of Pittsburgh----

"In thinking mathematically, or, as Einstein's sometimes said, formally, one takes the mathematical equations of the theory as a starting point. The hope is that by writing down the simplest mathematical equations that are applicable to the physical system at hand, one arrives at the true laws. The idea is that mathematics has its own inner intelligence, so that once the right mathematics is found, the physical problems melt away. Philosophers will recognize this as a form of Platonism.. Just how did Einstein's physical insight work? One part was an keen instinct as to which among the flood of experimental reports were truly revealing. Another was his masterful use of thought experiments.

Through them Einstein could cut away the distracting clutter and lay bare a core physical insight in profoundly simple and powerfully convincing form.. That geometrical way of conceiving special relativity is not Einstein's. It was devised by the mathematician Hermann Minkowski shortly after Einstein published his special theory of relativity. Einstein was reluctant to adopt Minkowski's method, thinking it smacked of "superfluous learnedness." It was only well after many others had adopted Minkowski's methods that Einstein capitulated and began to use them. It was a good choice. It proved to be an essential step on the road to general relativity. Einstein preferred to think of his theory in terms of the coordinates of space and time: x, y, z and t. The essential ideas of the theory were conveyed by the algebraic properties of these quantities, treated as variables in equations. Its basic equations are the Lorentz transformation, which, in Einstein's hands, is a rule for changing the variables used to describe the physical system at hand. The laws of physics are written as symbolic formulae that include these coordinate variables.

The principle of relativity of relativity then became for Einstein an assertion about the algebraic properties of these formulae; that is, the formulae stay the same whenever we carry out the symbolic manipulation of change of variables of the Lorentz transformation. The emphasis in Einstein's algebraic approach is on variables, not SpaceTime  coordinates, and formulae written using those variable, not geometrical figures in SpaceTime. For many purposes, it makes no difference which approach one uses, geometric or algebraic. Sometimes one is more useful or simpler than the other. Very often, both approaches lead us to make exactly the same calculations. We just talk a little differently about them. However there can be a big difference if we disagree over which approach is more fundamental. We now tend to think of the geometric conception as the more fundamental one and that Einstein's algebraic formulae are merely convenient instruments for getting to the geometrical properties. There is some evidence that Einstein saw things the other way round. He understood the geometric conception, but took the algebraic formulation to be more fundamental"

--End Quotes----

As for me, I grow up with the geometric definition :) and find it intuitively the easier one.
Anyway, I would still like to understand what you meant there? yor_on, Sat, 18th Sep 2010

"If you're in a windowless room and you can feel "gravity", you might in fact be in a room in a spaceship accelerating through space. You can't tell the difference, hence the principle of equivalence. However if there's a room above yours, and another and another, you can tell the difference between being in a very tall tower and a very long spaceship."

Where from did that one spring?

If I assume a spaceship built like a skyscraper, moving uniformly at one G without windows, it then would somehow present me another gravity than being in that same skyscraper placed on Earth, excluding spinning/Coriolis effects of course?

What would make it different? yor_on, Sat, 18th Sep 2010

I was showing you the discussion, yor_on. Read the Pete Brown paper too. 

It didn't spring from anywhere. It's just that you don't get to hear about this sort of thing. Have a browse on Born rigidity and the principle of equivalence.

You put a clock in each room, and plot height r against how much the clocks go out of sync. If you plot a 1/r curve you're in the spaceship, if you plot a 1/r curve you're in the skyscraper.

The thing about all this is that people are surprised about the fine structure constant being a running constant, because they get told porkies in magazines etc. It's the same kind of thing with the principle of equivalence. Farsight, Sat, 18th Sep 2010

Ahh, you're using the absolute mass of the Earth against the mass of the spaceship moving uniformly at one G? A new one to me, can you prove it?

Or maybe older than I first thought, it wouldn't be the Pound-Rebka Experiment you are referring too?

As for the Pete Brown paper, why don't you just tell me how you see it?
References are always appreciated though :)

The Pound-Rebka experiment yor_on, Sat, 18th Sep 2010

Peter Brown as well as Hans C. Ohanian seems to share the same view there. As Hans was the first one to share his misgivings about Einstein's theory's I will assume that Peter's pdf build on what Hans wrote. The general conclusion of Ohanian seems to be that he was wrong in most of his views, and that it was more blind luck than any genius that he got it as right as he did :) A rather smug and unpleasant attitude to the physics he introduced it seems to me?

So what have those two introduced in form of new thinking themselves Farsight? As for the theory of equivalence and its proofs? Really need to read more about it before saying where, and if, Einstein made a mistake in viewing it the way he did. For arguments sake, let's assume that he did, then gravity and acceleration can't be the same? Or is the author(s) view that he was right, but only from their proofs :) talk about taking up the fallen mantle.

It also seems as if Hans C. Ohanian believe the idea of lights invariant speed to be wrong? Or? No, not wrong, he's just insulted that Einstein defined it as a constant in SR :) without, as he sees it, giving an absolute proof of how to synchronize those clocks for different frames. :) Well, let me give you some news Hans, it was a theory, and still is. We've tested his premises since that, and he was right :) and there was actually proofs before that too pointing to light being an 'constant' from Maxwell's equations and Michelson-Morley results..

I don't know Farsight? Seems like much ado over nothing? And even if the Equivalence principle would be proved totally up the walls it won't invalidate GR, not as I understands it?. That he didn't take up the 'tidal forces', as we call it today, I believe to be his way of presenting an idealized concept. What you could argue is that he made conceptual jumps in his reasoning, not validating all of his conclusions in painstaking detail. But he validated them good enough for his contemporary physicists to accept them. Sh* that's part of why he was a genius, his ability to make those 'jumps' and still get it right.. And that's why I ain't impressed with those guys either. Let them present a better theory, something new and 'unprecedented' like Einstein's ideas was felt to be then. That we in hindsight find others having reached proofs for his conceptions doesn't invalidate his genius. Turn it around, if all those other guys had it right before him, why didn't they present the 'theory of relativity'? and don't tell me they did, because then it would have been them we would have argued about :)

Naah. yor_on, Sat, 18th Sep 2010

I just want to point out that the results from the southern hemisphere are opposite to the one from the northern hemisphere. Could it be an effect from the earth magnetic field (or ionosphere)? Could the light from these far away quasars posess special chromatic polarization properties? I guess we have to wait... CPT ArkAngel, Sun, 19th Sep 2010

Perhaps that's because there is a North Pole and a South Pole. Geezer, Sun, 19th Sep 2010

Do physicists understand what constants are in the mathematical sense?  constants are numbers added to a function containing one or more known variables that results in the production of a result. Constants represent unknown factors that apparently don't change sufficiently to be detected.  These factors could be variables that only change slowly or in which the change is so small that existing equipment lacks sufficient sensitivity to detect the change.

reasonmclucus, Sun, 19th Sep 2010

That's one way of expressing it, but if a constant was proofed to change it wouldn't be a constant anymore. "Constants are the terms in the algebraic expression that contain only numbers. That is, they're the terms without variables. We call them constants because their value never changes, since there are no variables in the term that can change its value. ."

That's also what makes this "fine structure constant" strange. If it's changing it would be nice to define which exactly of the three constants creating it, the charge of the electron, the plank constant or the speed of light, that no longer will be a 'constant'? Or all three of course. Also it would be nice to see a definition of what exactly it is seen as promoting those changes, if we now suddenly want to introduce different 'constants' depending on SpaceTimes geometry?

On the whole, a very weird result. yor_on, Thu, 23rd Sep 2010

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