Here we go again. I recommend investing in Kroger stock this year, because they’re gonna get a big boost in sales in TN from all these “snowstorms” wherein a meteorologist utters the word “snow” and 75% of the population immediately clears the milk, bread, and egg isles. (Apparently people only eat french toast during snowstorms?) As usual, I’ve been monitoring the progress of the forecast and find it interesting that the NWS hasn’t issued the winter storm warning yet, only a watch. I’m sure the warning will come, but it’s kinda funny that they’re hesitating, no doubt because of the giant snow fail from a few weeks ago. (To be fair, some areas around the midstate did get something close to the forecasted amounts, though no one really got the full 2-3 inches that was initially forecast…) This system is a little different than the last one, however. This one will most definitely have enough moisture to generate the 3-5 inches, unlike the last system which had moisture “issues.” The big limiting factor with this system will instead be temperatures. Nashville will literally be right on the dividing line between having an ice/rain mix and having an all snow event. If this system decides to track just 50 to 100 miles further north than the models think it will, that will cause more warm air to advect farther north, and we’ll end up having mostly rain friday changing to a little snow on the backside fri. night into sat. morning. If it decides to track slightly further south, we’ll have all snow, but much less of it, and areas to the south of us could actually see more snow than Nashville does. This system has a little better chance of “success” in giving us a good ol’ fashioned snowfall than the last one, but I wouldn’t place any bets yet.

Big rumors abound in the blogosphere about Obama’s budget proposal due to land in Congress on Monday. The biggest rumor is that it will completely cutout NASA’s Constellation program, which is the rocket system currently under development to not only replace the Space Shuttle, but also put men back on the Moon. I reported many times on the progress of the Augustine Commission and its recommendations for how NASA should proceed given that its current “trajectory” was financially unsustainable. One of the options they proposed was to eliminate the Constellation program and let commercial spaceflight companies like SpaceX takeover the duties of getting astronauts to the International Space Station and other low-earth orbit missions. I have a feeling that if the budget really does cut the Constellation funds, that’s where we’ll be headed next. Honestly I think it may not be a bad idea, because it would allow NASA to focus more on getting man further out into the solar system, and eventually to Mars. I tend to agree with Dr. Phil Plait’s (the Bad Astronomer) sentiments on the issue (as usual) but I’m not in total agreement with him that we should still go back to the moon. But then again, he’s the astronomer with a Ph.D and I’m not. For even more info, check out Universe Today. Check those blogs again on Monday afternoon, as I’d say they’ll be able to update waaaay sooner than I will once the actual budget info is released.

I just moved from Toronto to Cambridge (UK) so unfortunately I can’t go here, but if you are in Toronto, you should check out this talk next Thursday:

Cosmic Music – Astronomy through the eyes of the Billboard 100
Date: Thursday, February 4, 2010
Time: 8:10pm – 10:00pm
Location: Bahen Centre Room 1160 and McLennan Physical Labs 15th/16th Floors, 40 St. George Street, Toronto, ON

The passion for astronomy is universal and even plays itself out in music. In this talk, I (Mubdi) will be looking at tracks from the Billboard Hot 100 and the astronomy concepts they evoke: from general relativity to the birth of stars. Come join us for a whimsical take on North America’s favourite music and Astronomy!

Mubdi Rahman is a PhD student in the Department of Astronomy and Astrophysics theory at the University of Toronto. His primary research interests include understanding the effects of star formation on the environment of the galaxy as a whole. An avid astronomer from even his earliest of years, Mubdi is active not only in research but also in the promotion and outreach of Astronomy and Science as a whole.

“Chaos theory has a bad name, conjuring up images of unpredictable weather, economic crashes and science gone wrong. But there is a fascinating and hidden side to Chaos, one that scientists are only now beginning to understand. It turns out that chaos theory answers a question that mankind has asked for millennia – how did we get here?

Over this 2010 BBC 4 documentary “The Secret Life of Chaos“, Professor Jim Al-Khalili sets out to uncover one of the great mysteries of science – how does a universe that starts off as dust end up with intelligent life? How does order emerge from disorder? It’s a mindbending, counterintuitive and for many people a deeply troubling idea. But Professor Al-Khalili reveals the science behind much of beauty and structure in the natural world and discovers that far from it being magic or an act of God, it is in fact an intrinsic part of the laws of physics theory. Amazingly, it turns out that the mathematics of chaos can explain how and why the universe creates exquisite order and pattern. The natural world is full of awe-inspiring examples of the way nature transforms simplicity into complexity. From trees to clouds to humans – after watching this film you’ll never be able to look at the world in the same way again.” (description at YouTube).

[1 hour documentary in 6 parts: Part I (above), Part II, Part III, Part IV, Part V and Part VI. Enjoy!]

Partially inspired by xkcd

In physics theory we are going over classical mechanics of rotating/rolling bodies and conservation of angular momentum. As long as there are no outside forces contributing torque to an isolated system, angular momentum remains constant. The way I see it, the earth is rotating about its axis with a fixed velocity, and revolving around the sun at a different fixed velocity. The mass of the earth is obviously not changing, and gravity from the sun acts along the radius between the sun and the earth. For all terms and purposes, the earth is an isolated rotating system.

Therefore, in order for angular momentum to be conserved, the earth must adjust its own rotation based upon internal forces. If the earth spins in a counter-clockwise, theoretically any counter-clockwise rotation would increase angular momentum, and the earth would have to slow its spin to compensate and vice versa.  Since perpendicular velocities don’t contribute to each other’s angular momentum as efficiently, the farther from the equator you are the greater the effect.

So someday when I’m rich I am going to build two enormous flywheels, one on each pole, and control the length of the day. Right now they would be spinning clockwise furiously, speeding along this final week of winter break and then immediately reverse direction when you arrive. Sure, it doesn’t really affect time, but who’s gonna notice that everyone is going to bed half an hour earlier? Multiplied by 10 days, thats 5 hours closer to seeing you.

Maybe if you would start working on your apparation skills….

Diamond-based Quantum Computing

Dear all,

First of all…greetings to everybody viewing this blog. For the creation of this blog I am mainly thankful to some of my students who has repeatedly requested me to use such an interface of expressing and communicating. From long times back, I was also realizing the necessity for such a medium. Because, time restricted classroom teaching can not serve as a complete substitute for the teaching-learning process. Also, all the students can not be reached always. Some feels comfortable in typing rather than verbal communication. Hence, all these causes driven to create this effect of creation.

Again, all the best wishes to everybody…happy new year 2010 to all…let’s awake n share whatever is sleeping in mind…

L6 Che 1 – We covered some more intermolecular forces stuff with a bit of a focus on hydrogen bonds. And it seems I might have mislead you! Each water is H bonded to 4 others… Sorry!

5 Phy – You guys actually did really well (in slightly chaotic circumstances) to calculate and then measure the critical angles of glass and perspex.

In other news… I’m pretty excited about this:

We’ve been fairly busy lately on the equator.  I for one have been buzzing around like a fly and seeing parts of Thailand, Indonesia, Malaysia, and Hong Kong.  The last one being my favorite; what an incredible city!

Yet, in the mean time, we manage to get a paper accepted in Physical Review Letters that deals with putting entanglement and other correlations, like quantum discord, on an equal-footing.   The whole thing worked out to be rather nice as it is perfectly applicable for arbitrary dimensional multipartite systems as well.

We used the concept of relative entropy as the basis of work.  Relative entropy of entanglement is a well known measure.  Using the same approach we defined quantum discord, quantum dissonance, and classical correlations.  Quantum dissonance is new quantity that we introduced, which is similar quantum discord but excludes entanglement.

Our work simplifies comparing different correlations.  Till now, there was no clear method to compare quantum discord with entanglement for instance.  One can compare concurrence and discord, but what does that mean?  With our methods relative entropy of entanglement is computed in the same way as quantum discord, and so comparing the two is perfectly legitimate.

Our definition of discord differs from the original definition.  We show that the definitions are closely related and therefore we are not diverting too much from the original spirt of quantum discord.  I think the results in this paper will enable many to do new computations that are pertinent.

Origin of the Term – In 1867, in a letter to fellow physicist Peter Tait, the great Scottish physicist James Clerk Maxwell proposed a thought experiment.  He postulated a chamber divided by an impermeable partition into two equal parts.  Both part contained equal amounts of a gas at equal temperatures.

He then proposed a “finite being[1]” that could open and close a door in the partition at will.  He endowed this being with the ability to discern molecular speeds and positions.  The being then proceeds to open to door to fast molecules moving from space A to space B, and to slow molecules moving from B to A.  The being closes the door when opposite conditions occur.

In this manner, the being brings about a situation where B contains a hotter gas than does A.  This temperature differential can then be used to drive a heat engine and to do work in violation of the Second Law of Thermodynamics—a law that Maxwell himself had earlier worked to prove most rigorously.

We need not concern ourselves either with Maxwell’s motives (entirely laudable) or the Second Law (still generally accepted) at this point.  Instead, let us consider the experiment itself.  Let us look at the experiment’s defining characteristics.

Essential Characteristics of the Demon – The “demon” has two essential characteristics.  Firstly, he can distinguish between fast molecules and slow ones.  Secondly, he can either pass or bar the passage of molecules through a plane depending upon their speed.  Simply put, the two characteristics enable the demon to engage in molecular selection.

It should be noted that the experiment does not need a “finite being” to identify and segregate the molecules.  This task could equally well be done by a device or a force.

Such devices have been developed, although they do require some outside source of energy to drive them (no violation of the Second Law here).  The forces also exist and are ubiquitous.  They are our—by now familiar—forces of intermolecular attraction.

The Demon in the Interface – In earlier papers in this series, we saw that each of the changes of phase which water undergoes also involve molecular selection and segregation.  Vaporization and melting involve the preferential selection of faster molecules.  Slower ones are rejected.  Condensation and freezing involve the preferential selection of slower molecules.  Faster ones are allowed to continue about their business. In each of these cases, the “demon” is hard at work doing the same job as Maxwell assigned to him in his famous thought experiment.

The location of these acts of selection, of course, is not the partitioned chamber Maxwell described.  It is, instead, the interface between the two phases—a partition of sorts.  The agent of this selection is the collective forces of intermolecular attraction that play the role of demon and do the actual sorting.  Maxwell’s demon may thus be found everywhere water or ice evaporates, everywhere water vapor condenses, everywhere ice melts and everywhere water freezes.  Within the free atmosphere, the demon is ubiquitous.

Water, of course, is not the only substance playing host to the demon.  We may assume that this same sort of selection and sorting takes place at the change of phase of any substance have two or more phases.

Summary – Thus we see that Maxwell’s Demon does exist.  He goes by many names:  force of intermolecular attraction, surface tension, surface energy and so on.  But he exists and is hard at work.

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[1] By “finite” we have to assume that he meant that the being was not supernatural.  A supernatural being would not be bound by natural laws and would render the experiment moot.  By the way, Maxwell himself did not refer to the being as a “demon”.   Lord Kelvin  first called the being by that name.

Copyright 2007 by Patrick J. Tyson     www.climates.com