More on the Fine Structure Constant

Bonker writes "Neat news from the Beeb. It turns out that data collected from observation of quasars indicates that the fine structure constant of the universe, aka 'Alpha', may have changed since the universe began. It may have been very slightly smaller than it is right now. The article hints that other constants we're familiar with, such as high, holy 'c', may also vary over time. Of course values can't have changed dramatically, because that would mean that low-weight atoms such as carbon would be unstable, and without carbon, there wouldn't be anyone around to measure the fine structure constant anyway." We ran a story about this last year. It looks like the team has continued to check their work for errors and hasn't found any yet.

Comments

I want independant analysis and data.

[astrophysics]

It's that same group saying the same thing again. Although I haven't reviewed their latest paper, I remember that I wasn't impressed with the statistical analysis of their data, as of the previous paper.

Personally, I won't find the evidence convincing untill another group takes some their own data and gets similar results. Given that many astronomers have similar sentiments, it seems that giving VLT time to the same group seems not the best use of VLT time.

Of course, if no other astronomers find the likelyhood of the discovery worth the effort of making the observations, then it may be difficult to get independant confirmation. Given that it would be a really big deal if true, I think that says a lot about how seriously the astronomical community takes these claims.

No hints about c

[NoBeardPete]

The article actually doesn't really hint that 'c' is changing, which is good, because it's not clear what would be meant by that. The article says that several physicists have previously wondered if it could change. It then goes on to quote a modern physicist as saying that they were wrong.

I think c is best thought of as a man made constant. Just as I might say that there are 2.54 centimetres per inch, I can say that there are ~3*10^8 metres per second. Neither of these really contains any information about the universe outside of our perception of it. It is simply a statement of how one one system of measurement compares to another. 2.54 centimetres per second evaluates to unity (the number 1, with no units) if you actually evaluate it. Likewise, physicists commonly use unity as the speed of light, because in a very meaningful way, it is.

If I suddenly magically increased c by 10%, that would be indisinguishable from stretching the universe by 10% in every spacial direction. Consider that the speed of light it essentially unity, and that expressing it otherwise is really more a statement of our systems of measurement that we use than of physical reality. This makes it seem silly to say that I have magically increased c by 10% and makes it seem more reasonable to say that I have stretched the universe by 10% in every direction.

Re:No hints about c

[MarkusQ]

But since a yardstick is more tangible than the speed of light, people would prefer to say that the speed of light changed, and not the yardstick.

It may be more tangible, but it isn't "more constant." The length of a yardstick is determined by the number of atoms on a typical line running from one end to the other times the average distance between their centers along this line. The number of atoms won't change if you change c, but the distance between them (which is determined by the interaction between charges, which is mediated by photons, which move at c) will--it will change in exactly the way to make you think that c hasn't changed.

As the original poster was pointing out, c isn't so much a constant as a tautology.

-- MarkusQ

Re:Speed of light

[bravehamster]

(OT I know, but I couldn't let this go)

No. c is the speed of light in a vacuum. The slowed light down by passing it through a certain material.

Actually, this is also, technically, incorrect. The speed of light is a constant. Always. Light always moves at light speed. Now, the time it takes for light to pass through various mediums is different, but this is not because the light is being slowed down. It's because the light is hitting the atoms in the medium and is kicking the electrons in the atom to a higher energy state. When the electron falls down from its higher energy state, it in turn release a particle of light. You could go so far as to say that it's the same particle of light. With denser mediums, light takes longer to get through. In the sun, for example, the plasma surrounding the fusion core is so dense, the light from that fusion takes many millions of years to reach the surface. During those millions of years, the light is always moving at light speed. It just keeps running into stuff.

some background on 'alpha'

[ChenLing]

alpha is the coupling constant for the electromagnetic force.
In other words, it determines the "strengh" of the electromagnetic force. It is important because
a) it has no units (it's just a number, approximately 1/137)
b) it is easy to measure to a great degree of accuracy
c) it can be measured using a variety of different experiments
d) many fundamental phyiscal constants (such as c - the speed of light in a vacuum, e - the charge of an electron, and h - the Planck constant.

So a change in alpha would mean a change in one of the fundamental constants of physics.

For more information, you can read NIST's wonderful description.