Random Thoughts on the Universe

Tuesday, October 04, 2011

2011 Nobel Prize

The Nobel prize people have just announced that the 2011 prize for physics will go to the two teams that inadvertently discovered dark energy (or at least their leaders).

For those who haven't followed this story, here is a brief review.

Back in 1915 Einstein published his General Theory of Relativity which describes the properties of space, time and gravity. One of its predictions was that the size of the Universe is changing - but Einstein didn't like that so he added an extra term called the Cosmological Constant whose sole purpose was to stop the Universe from growing.

A few years later Hubble discovered that the Universe is expanding, and Einstein felt rather foolish.

Now fast forward to the year 1998. Two teams of astronomers are cataloging distant supernovae (exploding stars) and independently discover that the supernovae are travelling faster away from us than expected. More study and they discover that in fact they are accelerating away.

Many explanations were proposed, but ultimately the only one the withstood further experimental data was that the Universe is not only growing as Einstein predicted and Hubble measured, but it is accelerating in size! (In other terms, the larger it gets, the faster it grows)

The only way to explain this is to either alter the laws of gravity which are valid for all other experiments or to add a large amount of mysterious substance called dark energy. In fact other experiments in the mid 2000s have determined that nearly three quarters of the energy in the Universe is in this dark energy form, but no one can explain what it is. (A leading candidate though is Einstein's Cosmological Constant but with the sign reversed).

So here we are 13 years after the discovery, and more evidence mounts for the existence of dark energy but with still no evidence for what it is. A most interesting mystery, and one that certainly warrants a Nobel Prize for its discoverers!

Wednesday, April 06, 2011

A New Discovery

There is a rumor circulating through the particle physics community that this afternoon the Fermilab particle accelerator team is going to announce preliminary results that indicate they may have discovered a new fundamental particle.

The rumors are claiming that the data shows a massive particle which is decaying into light quarks (which are the ones that form all of the protons and neutrons in the Universe), which adds to the excitement. The only particle that theorists have strong motivation to expect to find is the Higgs particle, which I have discussed in previous articles, and which gives mass to all the particles in the Universe. The problem is that the Higgs we expect to find will decay to very heavy short-lived quarks.

And that means that this new discovery is not the Higgs, and it is not any other particle in the Standard Model. If the data is real, it indicates an unexpected discovery of the first new particles or forces in several decades (the W,Z bosons and the top quark were both predicted before they were discovered).

But as always the theorists have plenty of candidates, even if they are not as well defined:

  • Dark Matter: The first candidate that physicists will discuss is dark matter. We know from astrophysics experiments that 95% of the energy in the Universe is not included in the Standard model, and roughly a third of that is a form of electrically neutral matter dubbed dark matter. But aside from its existence, none of its properties are known so this new discovery could indicate any of a hundred dark matter candidates. Some of the experiments that have searched for dark matter in the galaxy have indicated a candidate which is too light to decay into the heavier quarks, which agrees with this new data.

  • Supersymmetry: There are two classes of particles, fermions and bosons, and to make the Standard Model work at higher energy levels requires a symmetry between them that has never been observed. As with dark matter, there are hundreds of models for this supersymmetry and several of them could be adjusted to explain this new data.

  • Extra Dimensions: For almost a century physicists have considered the possibility that the Universe contains higher dimensions, with various properties. Several of these models contain a second complete copy of the Standard Model with masses above what previous experiments have been able to achieve. It is not difficult to model a higher mass copy of the u and d quarks that decay to their lighter counterparts in the Standard Model, in agreement with the observations. Because of the limited energy range of the Fermilab experiments, only the heavier u and d quarks can be produced and not the b and t quarks which would decay to heavier quarks, which makes this another prime candidate.
  • Fourth Generation: This one is a little harder to justify, but is still interesting. The Standard Model is neatly organized with 24 fermionic particles divided into three generations, each with two classes (quarks and leptons), each class divided into particles and antiparticles. There is no reason to exclude a fourth generation of particles, which would be very heavy and would quickly decay into lighter quarks. The downside is that they should prefer to decay into the third generation quarks rather than first generation, but that could be explained with a suitable model.
Of course theorists are notorious for generating thousands of models to explain a single anomaly, so this list is far from exhaustive. It must also be remembered that these large experiments often announce data that ends of being just an error or a statistical anomaly, and they end up meaning nothing.

For now all we can do is watch and wait...

Wednesday, December 29, 2010

The Year in Review

As 2010 comes to a close, it is a time to reflect on how the world has changed over the course of the last year. Here are a few highlights from the physics community:

  • The Large Hadron Collider finally starts! That's right, back in March after a year and a bit of delays, they finally fired up the biggest collider ever built. By the end of November the beam energies had reached 1.18 GeV officially making the LHC the highest energy particle accelerator in the world. We can only imagine what next year will bring in new data.
  • Einstein Was Right! In April, data from the Abell 3376 galactic cluster confirmed the prediction of general relativity, postulated by Einstein over 95 years ago and striking another blow against modified theories of gravity.
  • Symmetry Breaking at Fermilab? May saw the announcement from the team at Fermilab that they had discovered a rare B-meson decay which produced more matter than antimatter (or more precisely, it was more likely to decay into matter than into antimatter), raising hopes that the Universe's imbalance may finally be explained. As yet the asymmetrical decays have not been confirmed in other experiments, and most likely were regrettably only a statistical error.
  • Questionable Xenon? Also in May we saw the release of data from the Xenon experiment which suggested the two leading experiments, CDMS and DAMA, were conflicting with each other and with smaller experiments making dark matter even more bizarre. As with the last result, it is most likely caused by questionable data and processing by the Xenon team.
  • Unexplained Oscillator. In June the neutrino community was stunned by results from both the MINOS and miniBoone experiments which gives different properties to neutrinos and antineutrinos. The muon-neutrinos and their anti-partners were observed to oscillate into other flavors of neutrinos at very different rates, which also violates the symmetry laws of the Standard Model. Could this indicate new physics, or perhaps a heavier fourth neutrino type? Only time and more data will tell for certain.
  • Titanic Life? June also saw the announcement from NASA/JPL that they had found chemicals on the moon Titan which would be consistent with methane based life forms. If the data holds up, it could indicate the presence of other life within our very own solar system!
  • A Higgs? Back in July the physics world was buzzing with rumors that the group at the Tevatron had seen signs of a Higgs boson, beating out the LHC for the discovery. Unfortunately the results didn't appear in any formal reviewed format, so they were probably only rumors.
  • A Mirror Earth: In September astronomers were excited to discover a planet about 20 million light years away which appears to be in the perfect place to have liquid water. And as astrobiologists know, liquid water means a good chance of finding extraterrestrial life. Anyone ready for a 40M year tropical vacation?
These are just a few of the exciting new results in physics in the year 2010. The trend seems to be new data suggesting interesting new physics and new particles, but no hard evidence yet. But with the LHC just now gearing up for a serious attack on multi-TeV energy range, 2011 could be a year of decisive results. We look forward to reporting some amazing new discoveries in the coming year!

Tuesday, November 09, 2010

Online Roulette Scheme...

We normally don't comment on internet get-rich-quick schemes, but this one caught our attention because it claims to mathematically guarantee a profit.

The setup is that you use an online casino to play roulette. You start by selecting a colour - say Red - and betting $1. If you win, you gain $1 and repeat the process. If you lose, then you double your bet to $2 so that if you win you gain $2 creating a net profit between the two spins of $1. If you lose, you double again to $4 so that a win again creates a net profit of $1 over all the spins. So everytime you win, you increase your total profit by $1 and the losses are balanced out by the next win. They usually add a comment about how the probability of losing 8 times in a row is only 0.5% so you are certain to win sometimes.

It is complete bunk.

Unfortunately a lot of otherwise intelligent people fall for this because it seems to be mathematically certain that you will eventually win and that you can keep winning until you quit playing. But look closer...

On the first spin you have an equal chance of winning or losing $1, so your average profit is $0. If you win, then the second spin is the same, with an average profit of $0. Suppose you lost the first spin, and then bet $2. Once again, you have an equal chance of gaining or losing that $2 and so the average winning is still $0. This will be true no matter how much you bet and how often - you can always expect to just break even.

Consider the odds for the first 3 rounds. The probability of 3 wins is about 12.5% and you gain $3. The probability of three losses is the same, and you lose $7. The probability of winning the first time and losing the next two is also the same, with a loss of $2 while losing once and then winning twice gives a profit of $2. You might win twice and lose the third, giving you a net profit of $1, but if you lose twice and win the third then you get only a $1 profit. Add up all the possible runs of three rounds, and you find again that you only break even.

It is true that the odds of losing 8 times in a row are small - only 0.5% or so. But if you follow this method, that run of losses will cost you $500! The odds of winning 8 times in a row are also 0.5%, and following this scheme you gain $8. So you have an equal chance of winning $8 or losing $500 - is that really a good bet?

Of course breaking even is not so bad, except the game described here is not exactly the way roulette is played in most online casinos. Usually there is a small probability of neither black nor red, and in that case you always lose. And that small loss will eventually take all the money you started with...

That is certainly no way to make a fortune!

Sunday, October 10, 2010

This is a very Special Day!

Or maybe not...

But it is 10.10.10 (October 10,2010) and if that is taken as binary, it transforms into 42! And as we all know 42 is the answer to the ultimate question :D

Friday, October 01, 2010

A New Earth?

There is an interesting new result from the astronomy community. It seems that they have found a planet about 20 million lightyears away that is in the perfect zone in its system so that it could have liquid water and temperatures that support life.

Considering that only fifteen years ago there were no known planets outside of our system, this is quite an accomplishment. Of course it doesn't guarantee that it has life on it, but it is perhaps the best candidate yet.

Monday, September 06, 2010

A Variable Constant

We just received word of a new result that could have major implications for physics if it is confirmed. Apparently a team of astronomers/astrophysicists in Australia have determined that the fine-structure constant has a spatial dependency.

In particle physics, there is a constant which determines the electrical charge of the electron and all other charged particles - the fine structure constant. If this constant is higher, then the electrons and protons in all matter have a stronger binding. If it is lower, then the atoms are less bounded (and may not even form). As it turns out, the constant is in a range of values that are required to support life, but there is no reason why this should be so.

The new result indicates that the fine structure constant takes on different values in different parts of the Universe. That would suggest that we happen to live in a nice part of the Universe where life can exist, and that there is no need to fine tune the laws of physics to get that result.

On the theoretical side, it indicates that the electromagnetic coupling of particles is far more interesting than previously thought. One possibility is that there is a new particle which has never been detected before, and which essentially shields the electron and proton from electric forces. And if that is true, there is no telling what technological advances could be gained from a variable electric charge.

As I have said many times before, this is just a preliminary result and many times they don't hold up under further scrutiny. But it is interesting to consider and it will be interesting to see what develops from it.

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