Thursday, November 29, 2012

Does The Universe Have A Purpose?

A fun video, no matter which side of the fence you fall into.

At the very least, you can understand why, if we simply look at it "the way it is, rather than the way you want it to be", science has more evidence in favor of the universe having no purpose than the other way around.

I guess I'm with the e-coli bacteria in the video that asked for "more poop!".


Wednesday, November 28, 2012

Fermilab's Physics Slam Video

I mentioned earlier about the first Physics Slam at Fermilab, and ended the blog entry with the question on where the video for this event is.

Well, ask and you shall receive. The video for this physics slam is now available online.


How Quickly Does A Photon Reach c?

I've seen this question numerous times. The premise here is that while a photon travels at c in vacuum, it wasn't "born" with that speed. Somehow, after a photon is created at some low speed (zero?), it then accelerates to c. So I often get asked on how quickly does it reach c.

There are several problems with such a question, and this certainly qualifies as a "When did you stop beating your wife?"-type of question. Why? Because it assumes, a priori, that photons CAN have speeds other than c in vacuum. This is not verified. So the idea that a photon gets born with some low speeds is not an idea that has any physical basis, and thus, the starting point is all wrong.

Secondly, there is a problem in reconciling our experimental evidence with such a scenario. Let's look at this carefully.

Say we have a body that is initially at rest. at some point, emits a particle, as shown in the figure below.
The larger body moves with velocity V, while the smaller body moves with velocity v_i. These two values are related to each other via conservation of momentum.

Now, let's say that the smaller body then accelerates, by some means, to some final velocity, as shown below.

However, this final velocity v_f has no directly relations to V, i.e. it isn't correlated to V since the conservation of momentum of the two bodies no longer is relevant here. v_f no longer carries any direct information about V.

So let's look at what we know about such a thing. Atomic recoil, electron recoil, and a while bunch of other experiments on photo emission and photon collision experiments have shown that what we measure in such interactions totally conserve momentum. In other words, we measure v_f (since it was already at c for photon), and this v_f is still correlated to V via a direct conservation of momentum. This clearly means that v_f is equal to v_i, and therefore, there is no "acceleration" of photons

This scenario applies to a whole zoo of fundamental particles as well since the same conservation law applies to many  such interactions involving these particles.


Tuesday, November 27, 2012

What Happens When A Theory Is Wrong?

This has happened a lot of times in the history of physics. However, we could be confronting one right now on a very prominent theory - Supersymmetry.

This article by Marcelo Gleiser briefly looks at how physics often proceeds, and what is the fate of Supersymmetry after so many searches for it have failed to produce anything it is predicting that is unique beyond the Standard Model.

Given the lack of data in support of supersymmetry after all these years, why is the theory still considered viable?

The complication comes from the way mathematical models depend on various adjustable parameters. For example, the decay rate of a particle may depend on its mass and the way it interacts with other particles; if certain types of decays aren't seen, parameters can be changed to reflect that. The model may be made to hide from available experiments. And given that technology has more concrete limits than the imagination of theorists, a model may always be beyond the detectable.

How, then, can such types of models be ruled out? Well, simpler versions may be ruled out when the tweaking of parameters becomes so extreme that the model loses its original motivation: it explains nothing and becomes too cumbersome. Or a forbidden particle is discovered. Then there are always the more complicated versions, with more parameters that are harder to rule out.

The point is that there isn't a clear-cut answer. The physicist Max Planck used to say that wrong ideas don't die out, their proponents do. It will be interesting to watch what will happen in the next few years with supersymmetry and its proponents if tests keep producing negative answers.
This will become even more interesting if the LHC sees no convincing evidence after it boots its collision energy in a couple of years. While I am certainly interested in the physics, I am equally fascinated to see how the high energy physics community, and the Supersymmetry advocates, handle the outcome that they will get from that run.


Sunday, November 25, 2012

What Is Touch?

I see this question frequently being asked in public forum, especially on Physics Forums. Hopefully, this video provides a good start in answering such a question.


Friday, November 23, 2012

Fermilab's First Physics Slam

I'm sure this was a lot of fun and involves a level of performance and entertainment.

Fermilab had its first ever Physics Slam. And from the report, it sounded like it was a Smash! :)

The occasion was the laboratory's first ever physics slam. A physics slam is kind of like a poetry slam—the five contestants were given 12 minutes each to explain a complex particle physics concept to an auditorium filled with laymen. And they had to do it in the most entertaining way they could, because audience applause determined the winner.
Now, where are the videos of the event?


Thursday, November 22, 2012

Why Do Physicists Care About Finding The Higgs?

This is a very short and informative article on why many of us care so much about finding the Higgs. The reasons may be quite different from those understood by the general public. This article, along with the one I posted earlier, might help in correcting several misconceptions about the Higgs.

Happy Thanksgiving to those in the US.


Wednesday, November 21, 2012

The Origins of the Elements

If you have an hour to spare, here's something you might either want to watch, or just listen in the background.


Tuesday, November 20, 2012

Dance To String Theory

It is no secret that I've made fun of many of these efforts to incorporate physics with dance. I'm sure they are of high artistic caliber, but I question the "reason" for doing such a thing, and the effectiveness of it. In other words, if I don't tell you what this is all about, can you decipher it for yourself?

I've mentioned before several attempts at using various physics topics or principles as a dance motif. Read here, here, here, and here. Add this one to the list.

The choreographer has been working with Andrew Melatos, a theoretical physicist at Deakin. Melatos is an expert in string theory, the strand of particle physics that attempts to reconcile quantum mechanics and general relativity. The pair's collaboration has led to Multiverse, an "innovative, animated dance work" that is being workshopped before a premiere next year.

Stewart says Multiverse - taken from the term coined by 19th-century philosopher William James, who put forward the idea of multiple parallel universes - will be a combination of live dance and three-dimensional animation, requiring the audience to wear 3-D glasses.
That sounds like a hoot!

I'd like to ask this: without invoking or being told about the "physics" behind the dance, can you enjoy the performance as is? If yes, then how come one doesn't sell it as such?

I again am curious about why these things are done. I mean, sure, they'll argue that this is another way to "visualize" various aspects of physics, and visualize this from an artistic point of view. But (i) why; (ii) is this really accurate; (iii) is this really necessary? Did someone who had no idea about physics saw this and suddenly got inspired to either study physics, or support physics? Did someone who didn't quite understand a certain aspect of physics suddenly understands it better after seeing such a performance?

I'm not saying this shouldn't be done. I'm just awfully curious on why and what are the consequences of such a thing. After all, a lot of effort, time, and money were spent for one of these things. It has to mean SOMETHING!


Monday, November 19, 2012

Finally, A Direct Detection Of Time Reversal Symmetry Violation In Elementary Particles?

It appears that we now have evidence of a direct detection of time reversal symmetry violation in elementary particles. This detection appears to be clearer and less ambiguous than before, and doesn't rely on the detection of CP violation.

It also seems that this is a result out of BaBar, which came from SLAC's linear collider before it was permanently shut down and converted into the LCLS. So that old gal is still giving us results from her grave!


Saturday, November 17, 2012

Top 5 Misconceptions About The Higgs

This appeared a few days ago, but better late than never. It lists the top 5 basic misconception about the Higgs, especially as reported in the popular media.

1.      Misconception: The Higgs particle gives other particles mass.
 Correction: The masses of fundamental particles come from interactions with the Higgs field. 

"You see this statement all the time, but how would another particle even 'give' another particle mass?" Kruse asks, explaining truly it's the Higgs field that provides mass to fundamental particles, such as quarks, electrons and neutrinos.

The Higgs particle is a consequence of the Higgs field. By discovering the Higgs particle, it shows the Higgs field exists. In the math that physicists use to understand the Higgs boson and field, there is a piece of an equation that they interpret as the existence of a Higgs boson, which they see as a point-like particle resulting from the Higgs field "curling in" on itself, like a knot in a spider's web. Physicists can't interpret the Higgs boson itself to be giving anything mass, but by interacting with other particles, they can argue that the Higgs field is giving resistance to the particles' motion, thereby giving them mass.

2.      Misconception: The Higgs field generates the mass of everything.
 Correction: The Higgs field generates the mass of about one percent of observable matter and possibly all of dark matter.

The Higgs field generates mass for quarks, which are the building blocks of protons and neutrons. The protons and neutrons, in turn, form the nuclei at the core of atoms, which are the building blocks of molecules, proteins, cells, plants, animals, planets, stars, galaxies and all the stuff we see in the universe. The mass of quarks accounts for only one percent of the mass of a proton or neutron. The other 99 percent of the mass of observable matter comes from the energy that binds protons' and neutrons' constituent quarks together.

It may seem kind of strange to think that the discovery of the Higgs boson, and thereby the existence of the Higgs field, means scientists have discovered an explanation for only one percent of the observable mass of everything we see. But, "that one percent is the mass of the fundamental constituents of the universe," Kruse says, adding that the Higgs field has also incredible consequences for the structure of atoms and molecules. "If the already small mass of electrons was zero, as it would be without a Higgs field, then everything would just disintegrate," he says. "All the atomic structure we are familiar with wouldn’t exist. We wouldn’t exist. There may still be matter, but it wouldn’t be the same. There certainly wouldn’t be life as we know it."
Also, unobservable matter also wouldn't have mass. Scientists believe this unseen, or dark matter, comprises more than 80 percent of the matter of the universe, but it doesn't interact strongly enough with anything to allow its direct observation. Yet, because it has significant mass, "it must interact with the Higgs field and that's another key point," Kruse says. "The Higgs field generates about one percent of observable mass, with the term 'observable' being a very important qualifier, because the Higgs field may be responsible for the mass of all dark matter."

3.      Misconception: The Higgs boson creates the Higgs field.
 Correction: The Higgs field generates the Higgs boson.

Kruse says that some of the best physics writers have shared this misconception, but the Higgs boson does not create the Higgs field. The opposite is true, because the Higgs boson is a consequence of the Higgs field. The field itself became noticeable to fundamental particles existing in the very early universe about a billionth of a second after the Big Bang, when a fundamental symmetry in the universe, called the electroweak symmetry, broke.

4.     Misconception: The Higgs field is what scientists used to call the aether.
Correction: The Higgs field isn't a medium; it's a field of energy. 

In the late 1800s, scientists conceived of the aether as a way to explain how light spreads through space. At the time, scientists reasoned that because sound waves needed a medium through which to travel, then so should light. "With the advent of the theory of relativistic electrodynamics, the need for an aether disappeared," Kruse says.

When physicists and writers try to explain the Higgs field, they often describe it as an "icky, gluey" medium where, as particles move through it, the resistance they experience generates their mass. "It's not a horrible way of thinking about it, except that the field is not any type of sticky mechanical substance. It's not a medium, but rather a type of energy that uniformly pervades all of space," Kruse says.

5.      Misconception: There was a "eureka moment" for discovering the Higgs boson and the   existence of the Higgs field.
 Correction: There will never be eureka moments for discoveries such as the Higgs boson and the Higgs field at the Large Hadron Collider.

"I think this experimental misconception is a whole story in itself," Kruse says. "The discovery is based on a laborious accumulation of evidence, which at a certain point we deem strong enough to claim victory, based on a very low probability that it could be due to something else," he says, adding that "there's no single eureka moment where we look at an event and say that's a Higgs."

Friday, November 16, 2012

Why Is Li Atom Ground State In a 1s2 2s Configuration?

You would think that something that is well-established in both physics and chemistry textbooks would not reveal any more surprises, but you (and we) are wrong.

This is an interesting preprint, and it got me captivated for several minutes. First of all, let's set the scenario.

In the periodic table, as one go from H to higher numbered atoms, one start filling up various atomic orbitals. So you have H having 1s^1, He with 1s^2, Li with 1s^2 2s^1, etc.. etc. The interesting thing here is that with just the electron-ion interaction being accounted for, the 2s and 2p states in Li are degenerate, meaning they both have the same energy. So why would the 2s state gets filled first ahead of the 2p?

The standard textbook explanation here is that the 2p states, due to the geometry of the orbitals, tend to get shielded more by the 1s electrons than the 2s states. Thus, the 2p states have a higher energy than the 2s states.

This preprint claim that that explanation is flawed. They showed that what is really at play here is the electron-electron interaction, which is often neglected in many of these multi-electron systems with low atomic number. In their calculation, the interaction between 1s - 2s electrons produced a lower energy state than the interaction between 1s - 2p electrons. This is the main reason for Li ground state to be what it is, and not due to "shielding".

I'm sure this is being submitted for publication somewhere. The paper is not that difficult to follow for advanced undergraduate physics students.


Thursday, November 15, 2012

Just The Higgs And Nothing Beyond

The Kyoto conference going on now gets to see more results out of the ATLASand CMS detector at the LHC. So far, they are confirming the data of the apparent Higgs from last year, but nothing much beyond that.

Alas, most of the Higgs results being presented this week at the Hadron Collider Physics symposium in Kyoto, Japan, have been well within our standard understanding. Physicists at ATLAS and CMS, the two largest particle detectors at the LHC, have about double the amount of data they did in July; this new data hasn’t dramatically changed the tentative conclusion that the LHC is seeing a plain-old Standard Model Higgs.

We already heard on the other result that still showed no sign of SUSY. That Standard Model is gripping us real tightly!


Tuesday, November 13, 2012

Optical Atomic Clock Outperforms Cesium Clock

Our expertise in Metrology seems to be improving quite dramatically nowadays. This is one such example.

Now, in Physical Review Letters, Alan Madej and colleagues at the National Research Council in Canada report they have greatly increased the accuracy with which another atomic frequency standard, the optical transition in an isolated strontium ion, can be measured. Furthermore, the precision of their frequency measurement now supersedes that of the existing cesium standard, which could lead to the adoption of a new frequency standard for defining the second as the basic unit of time.
You can get a free copy of this paper at the link provided above.


Monday, November 12, 2012

More Results NOT In Favor Of SUSY

I will admit that I am not sure of significant this or how big of a "setback" it is for SUSY. But this theory is in need of some hint of an experimental rescue, and it didn't get it from this latest result.

If superparticles were to exist the decay would happen far more often. This test is one of the "golden" tests for supersymmetry and it is one that on the face of it this hugely popular theory among physicists has failed.

Prof Val Gibson, leader of the Cambridge LHCb team, said that the new result was "putting our supersymmetry theory colleagues in a spin".

The results are in fact completely in line with what one would expect from the Standard Model. There is already concern that the LHCb's sister detectors might have expected to have detected superparticles by now, yet none have been found so far.
 This certainly does not rule out SUSY, but it is getting to the same level as cold fusion if positive experimental result does not come soon.


Sunday, November 11, 2012

Open Letter to the President: Physics Education

Here's a very timely "letter" to the US President regarding physics education in the US.


Friday, November 09, 2012

You Can Teach Yourself To Think Like A Scientist - Part 1

It's true, and it isn't that difficult at all!

I'm going to start a series of essays on the things I see everyday in which the person involved either were using the same analytical technique as a scientist would, or the person simply dropped the ball and did not really thought things through as a scientist would. What I'm hoping to show here is that in our everyday lives, we DO make some decision in what to choose, what to believe in, and what to accept as valid. In many cases, these things come instinctively, or they have to be thought out a bit more. However, depending on what methodology we use to arrive at a conclusion, what we accept be not be valid because of the flaw in our reasoning or analysis. And I'm not going to restrict myself just with examples from science. I'm going to point out reasonings, methodologies, flaw in logic, etc.. from all and any parts of our daily lives as I can find.

But to start out with, we'll go back to the world of science and see what we have here. In a post in the Physics Forums, a member asked this question:

Why is it that lower frequency EM waves are aloud to pass through objects, but high..

... frequency are absorbed, like gamma rays. I would think it would be the opposite. So whats the physical reason?
Ignoring the spelling mistake, and without providing an answer to this question, there are already flawed methodology here in which the person who asked this question did not follow.

First is the "general rule" that this person appear to have observed, which is (to paraphrase):

Low frequency EV wave has more penetrating power than high frequency EM wave.

We are then asked to explain this. But wait a second! Is this true? As scientists, before we answer a question, we have to examine what that question is asking, and whether that question itself is true! This is because, if you try to answer a question that is based on faulty premises, then you're wasting your time on something that isn't true! So let's examine this then.

Now, presumably, this person is quite familiar with x-rays. After all, many of us has had to have one for one reason or another. x-rays have higher frequency than, say, visible light. Yet, we know for a fact that x-rays are more penetrating in our bodies than visible light. What just happened here? I've just given an example that thoroughly contradicts the assertion made in the question. I've shown something where a lower frequency is NOT more penetrating than a higher frequency EM radiation. And I've used an example that practically everyone is familiar with, not some exotic physics experiments that only someone with a PhD can comprehend! In other word, if you think you've drawn some sort of a conclusion, see if you can find an example that contradicts that conclusion. If you do, then it should cause you to ponder, at the very least, if your conclusion is universally valid, valid most of the time, valid some of the time, only works in a special case, or it is truly nonsensical.

Now, as scientists, we always try to see if there are any contradictions to things that we thought we understood. If we have a "rule" or theory that we go by with, and then see something that does not seem to fit that description, this means that our understanding or rule either may not be complete, or that something may be governed by descriptions that are different. In fact, contrary to popular beliefs, scientists LOVE such contradictions, because it means that there are things we don't understand and still need to be studied - things things keep us fascinated AND employed!

The moral of the story here is that, even without understanding the physics of what is going on here, a person without any physics knowledge can already do his/her own self-diagnosis and, at the very least, realize that the assertion made in the question is really false. Low frequency EM radiation does NOT ALWAYS penetrate a material more than high frequency EM radiation. One does this simply by being aware of already-established knowledge that most people already know. This is what I mean by thinking things through analytically, and in this case, using just common knowledge. We all posses this ability, but some of us have it more honed than others. It is this ability that needs to be brought out more often, and more deliberately.


Measurement of Electron Electric Dipole Using Solid State Experiment

Another example where the so-called "applied" physics field can make as fundamental of a contribution to physics knowledge as any other "pure" field.

A while back, a new and improved measurement of the electron dipole moment using beams of electrons reveals that there is still no internal structure to the electron. A new experiment has significantly improved the ability of a solid state experiment to measure the electron dipole moment.

The electron’s EDM must be collinear with its spin. Solid-state EDM searches, therefore, typically apply an electric field to a sample and try to measure the induced magnetic signal. Stephen Eckel and colleagues at Yale University in Connecticut perform such an experiment with Eu0.5Ba0.5TiO3, a ceramic with a high density of unpaired, unordered spins, and a sizable ferroelectric response. This means that an external electric field creates an even larger internal electric field for the spins. The authors place a sensitive magnetic pickup loop between two 12-mm-diameter, 1.7-mm-thick disks of Eu0.5Ba0.5TiO3 and apply a series of short electric field pulses to modulate the signal from the EDM and cancel out stray fields.

Eckel et al. conclude that if the EDM is nonzero, it cannot be greater than 6.05 x 1025ecm. Compared with the best limit of 1.05 x 1027ecm from atomic beam measurements, it may seem like a losing battle to continue with a solid-state approach, but the prospect of new materials and lower noise measurements motivates continued research.
With the discovery of the same physics for a magnetic monopole in the spin-glass system, possible discovery of skyrmions, and the recent discovery of Majorana fermions, condensed matter experiments are producing a lot of fundamental results that used to be the sole realm of particle physics. The myth that condensed matter physics does not produce "fundamental knowledge" should be thoroughly destroyed by now.


Wednesday, November 07, 2012

Another Physicist In the US House of Representatives

Physicist Bill Foster won the seat to the US House of Representatives, beating incumbent Judy Biggert. He will be back in the House after losing his congressional seat 2 years ago.

I mentioned earlier if his talk at last year's TIPP conference on the life of a scientist in the US Congress. Here's a link to the power point document of that talk. Click on his talk titled "Applications of Analog Circuit Design to Life as a Scientist in the United States Congress".


Edit 11/9/2012: More coverage on this can be found at PhysicsWorld.

Monday, November 05, 2012

Can We Predict Everything?

This is quite consistent with the very latest result from last week.


Saturday, November 03, 2012

"Ridges" In High-Energy Collisions

It looks like Ruffles potato chips are not the only ones that have ridges.

New results out of the CMS detector at the LHC seems to produce "ridge"-like structure in the collision data between proton-lead. This observation has been detected before.

The first data from proton–lead collisions at the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider (LHC) at CERN include a "ridge" structure in correlations between newly generated particles. According to theorists in the US, the ridge may represent a new form of matter known as a "colour glass condensate".

This is not the first time such correlations have been seen in collision remnants – in 2005, physicists working on the Relativistic Heavy-Ion Collider (RHIC) at Brookhaven National Laboratory in New York found that the particles generated in collisions of gold nuclei had a tendency to spread transversely from the beam at very small relative angles, close to zero. A similar correlation was seen in 2010 at CMS in proton–proton collisions and then later that year in lead–lead collisions.
Of course, as expected, theorists are already out in force presenting various scenarios to explain this phenomenon. We simply have to wait for more data to come in before we can make any kind of rational decision on this.


Thursday, November 01, 2012

Oliver Heaviside

This month's issue of Physics Today has a terrific brief biography of Oliver Heaviside. If you've studied physics, mathematical physics, or even electrical engineering, then you would have encountered and used the fruits of his labor.

In physics, there many many of these unsung heroes that do not get the public recognition that they should. It is only through articles such as this, and highlighting them in blogs such as this one, that these figures will at least be known to a few more people that have never heard of them.