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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.
No. c is the speed of light in a vacuum. The slowed light down by passing it through a certain material.
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.
The number of dates I've had in the past year. Of course this tends to cause some division by zero errors.
--It's Pimptastic!--
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.
Arrr, it be the infamous pirate, No Beard Pete!
Whoa, time to change those #defines to doubles.
Quoth the article:
"If this is correct, it will radically change our view of the Universe. We have to be cautious but it could be revolutionary. We have seen something in our data - but is it what we think?"
I like it when scientists talk about their theories in this manner. On one hand you have a whole body of researchers, scientists, and journals who are so afraid to rock the status quo that they refuse to research (or publish) controversial information. On the other, you have scientists and/or crackpots who are so paranoid and skittish towards working within the peer reveiw system that we'll probably never gain access to their research, some of which may be quite important and revolutionary.
(I quit my physics major a year in and switched to CS. At what point do 'paranoia' and 'ego-building' become required courses?)
I think this is a nice middle ground. These guys have announced a neat finding, with the caveat that they are still in a thourough 'error-checking' mode and are looking for problems with their own research and are implicitly inviting others to do the same.
The next Slashdot story will be ready soon, but subscribers can beat the rush and slashdot the links early!
It's not possible to go faster than the speed of light in a vacuum. However, it is possible to go faster than light in some medium.
This actually happens fairly often in nuclear physics. Radiation given off by, say, radioactive waste in a nuclear power plant's storage pool can go faster than the speed of light in water. When it does this, you get the eerie blue glow everyone imagines with radioactivity (which usually isn't really there).
This effect is called Cherenkov radiation, unless I've forgotten how to spell.
It is not possible for any medium to speed up light, so far as in known.
The simplest way to understand why light slows down in a medium is to think of it this way:
Light is zooming along at its full vacuum speed, right? But, there are all these atoms there! Zillions of them! So, light runs into an atom. Luckily for light, the way this works is that it temporarily "charges" the atom, which then almost immediately (but not quite) "discharges" a photon going in pretty much the same direction with the same frequency. Depending on how many atoms there are, and how the atoms behave, this can have varying effects on the light.
This isn't really particularly accurate, but it's easy to understand and more or less vaguely similar to how it works.
Of course, IANAP.
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.
---- El diablo esta en mis pantalones! Mire, mire!
Alternately, if we're shrinking on a hyperbolic space (ie staying the same size on an ever growing space), then pi should be getting smaller.
Actually, unlike 0, 1, and e, pi is not "a fundemental constant", but a convenient artefact that allows circles and spheres to be expressed. For example, one can use any number "k", and express pi in terms of "k". The definition of k would be different, but that's ok.
For example, if k were pi/4, we would say that the circumference of the circle is 8kr, and its area 4kr^2. For diameters, circ = 4kd, and area = kd^2. This make the circumference and area k times that of the circumscribing square.
Also, I have played with a set of mathematics, that makes the surface of the sphere 8 pi r^2, with pi=3.14159265359 &c. This has an effect on the "rationalisation" in physics, where 4pi gets replaced by 8pi.
Mathematics has a lot of preconcieved notions in it.
OS/2 - because choice is a terrible thing to waste.
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.
"You have the option of insanity. I do not. And that makes me crazy!" - Brian to Angela, My So-Called Life
Everyone seems to love carbon. It is highly overrated if you ask me. Hydrogen, now there's an element...
python -c "x='python -c %sx=%s; print x%%(chr(34),repr(x),chr(34))%s'; print x%(chr(34),repr(x),chr(34))"
Hmmm. Maybe in a dozen billion years or so, my slashdot Karma may be worth more also.
Table-ized A.I.