Posts and news on science

Interesting posts

Beyond God and atheism: Why I am a ‘possibilian’

But good science is always open-minded, and the history of science is one of surprises and overturnings. Science is nothing but careful thinking, and careful thinking encourages an appreciation of the complexity of the world. The complexity encourages us to maintain several possibilities at once. In a single lifetime, we may have no way to remove the ambiguities from these possibilities.



Scientists isolate, hold, photograph individual Rubidium 85 atom

( — In a major physics breakthrough, University of Otago scientists have developed a technique to consistently isolate and capture a fast-moving neutral atom – and have also seen and photographed this atom for the first time.

Random numbers created out of nothing

Now Christian Gabriel’s team at the Max Planck Institute for the Science of Light in Erlangen, Germany, has built a prototype that draws on a vacuum’s random quantum fluctuations. These impart random noise to laser beams in the device, which converts it into numbers.

Sound can leap across a vacuum after all

Now a theoretical analysis by Mika Prunnila and Johanna Meltaus, both of the VTT Technical Research Centre of Finland in Espoo, suggests that sound may be able to leap across a vacuum separating two objects made of piezoelectric crystals. These crystals generate an electric field when squeezed or stretched by sound waves or other forces, and deform in an electric field.


Study shows real partners are no match for ideal mate

Our ideal image of the perfect partner differs greatly from our real-life partner, according to new research from the University of Sheffield and the University of Montpellier in France. The research found that our actual partners are of a different height, weight and body mass index than those we would ideally choose.

Unlocking the secret of beauty: Scientists discover the complexities of attractive female bodies

Scientists in Australia and Hong Kong have conducted a comprehensive study to discover how different body measurements correspond with ratings of female attractiveness. The study, published in the Journal of Evolutionary Biology, found that across cultural divides young, tall and long armed women were considered the most attractive.


Maxwell’s demon at work: information-heat engine

The second law of thermodynamics is considered to be one of the “strongest” laws of Nature.

The second law of thermodynamics ensures (through statistical probability) that two bodies of different temperature, when brought into contact with each other and isolated from the rest of the Universe, will evolve to a thermodynamic equilibrium in which both bodies have approximately the same temperature. (.)

Right away by reading the above definition we understand that the second law of thermodynamics has to do with statistics. In schools we learn that the 2nd law of thermodynamics is the expression of the axiom of conservation of energy, and that is the reason that it is so “strong”. What they don’t teach us is that conservation of energy is a statistical phenomenon that we experience in the macroscopic world, despite that this was demonstrated 150 years ago by James Clerk Maxwell with his famous demon thought experiment;

second law of thermodynamics.. if we conceive of a being whose faculties are so sharpened that he can follow every molecule in its course, such a being, whose attributes are as essentially finite as our own, would be able to do what is impossible to us. For we have seen that molecules in a vessel full of air at uniform temperature are moving with velocities by no means uniform, though the mean velocity of any great number of them, arbitrarily selected, is almost exactly uniform. Now let us suppose that such a vessel is divided into two portions, A and B, by a division in which there is a small hole, and that a being, who can see the individual molecules, opens and closes this hole, so as to allow only the swifter molecules to pass from A to B, and only the slower molecules to pass from B to A. He will thus, without expenditure of work, raise the temperature of B and lower that of A, in contradiction to the second law of thermodynamics….

One better understanding of the second law of thermodynamics is through entropy¹;

The second law of thermodynamics states that the total entropy of an isolated system must increase. Since the demon and the gas are interacting, we must consider the total entropy of the gas and the demon combined. The expenditure of energy by the demon will cause an increase in the entropy of the demon, which will be larger than the lowering of the entropy of the gas. (.)

The demon will consume energy and increase the energy of the whole system, so the second law of thermodynamics is safe again. But it really depends on what this demon is; what about if the demon does not increase the entropy of the system by operating in thermodynamically reversible² way?

In 1960, Rolf Landauer suggested these “reversible” measurements could be used to sort the molecules, violating the Second Law. (.)

The second law of thermodynamics is not safe again, and in order to defend it we have to understand what entropy really means;

In information theory, entropy is a measure of the uncertainty associated with a random variable. The term by itself in this context usually refers to the Shannon entropy, which quantifies, in the sense of an expected value, the information contained in a message, usually in units such as bits. Equivalently, the Shannon entropy is a measure of the average information content one is missing when one does not know the value of the random variable.(.)

Taking in account the above definition of entropy, then the arguments in favor of the second law of thermodynamics replace energy with information;

In 1982, Bennett showed that, however well prepared, eventually the demon will run out of information storage space and must begin to erase the information it has previously gathered. Erasing information is a thermodynamically irreversible process that increases the entropy of a system. (Many people run into this problem of running out of storage space on their own computers but fortunately there is a simple solution – deleting some of the unnecessary data. A Maxwellian demon could do the same thing, deleting earlier data. But memory erasure is by definition an irreversible process. Once you’ve deleted the data on a piece of memory, resetting all the bits to 0, it is impossible to reconstruct the original data from this string of 0s. This irreversible process increases entropy by k ln 2 per bit. Bennett realised that one bit of storage was needed for each Szilard cycle. The entropy increase when these bits are erased offsets the entropy decrease effected by the demon.(.)

Despite that even this argument does not “save” the second law of thermodynamics ³ it achieves an important transformation; energy is replaced with information, and the quest of defending the second law of thermodynamics can be understood in terms of information exchange.

Finally 150 years later scientists and engineers managed to create the first implementation of Maxwell’s demon; Physicists Convert Information Into Energy For the moment they don’t seem to care about the quest of defending the second law of thermodynamics, they are excited because they have a principle for creating a nano-scale engine that converts information to energy.

Update 30 Sep 2010


If you read  the article carefully it seems that the “conversion of information to energy” is not the case exactly;

It’s hard to overstate the significance of what they’ve done: they’ve been able to operate a nanomachine–a stair-climbing bead–using nothing more than information as the power supply. (.)

The camera is observing the bead and stops it from moving back downstairs, by changing the electrical field action that implies consumption of energy. Until they replace the macroscopic camera with something else that does not consume energy the second law of thermodynamics is safe from this challenge. (thanks flaredOne)


¹Entropy is a macroscopic property of a thermodynamic system that is a measure of the microscopic disorder within the system. It is defined by the second law of thermodynamics. Thermodynamic systems are made up of microscopic objects, e.g., atoms or molecules, which carry energy. According to the second law of thermodynamics, the thermodynamic entropy is a measure of the amount of energy which does no work during energy conversions.

²In thermodynamics, a reversible process, or reversible cycle if the process is cyclic, is a process that can be “reversed” by means of infinitesimal changes in some property of the system without loss or dissipation of energy. Due to these infinitesimal changes, the system is in thermodynamic equilibrium throughout the entire process. Since it would take an infinite amount of time for the reversible process to finish, perfectly reversible processes are impossible. However, if the system undergoing the changes responds much faster than the applied change, the deviation from reversibility may be negligible. In a reversible cycle, the system and its surroundings will be exactly the same after each cycle.

³ John Earman and John Norton have argued that Szilárd and Landauer’s explanations of Maxwell’s Demon begin by assuming that the second law of thermodynamics cannot be violated, thus rendering their proofs that Maxwell’s Demon cannot violate the Second Law circular. (.)

Schrödinger’s cat is deadalive

Posted in Physics by e1saman on September 26, 2010

I first show that in twitter, I don’t remember the user, but it’s great!

schrondinger's cat

So you think you are special!

Posted in comment, Philosophy, Philosophy of Science, Physics, Science by e1saman on September 23, 2010

special According to Lee Smolin in “The trouble with Physics” the standard model of Physics was based on Natures symmetries and the spontaneous symmetry breaking;

Spontaneous symmetry breaking is the process by which a system described in a theoretically symmetrical way ends up in a non symmetrical state. For spontaneous symmetry breaking to occur, there must be a system in which there are several equally likely outcomes. The system as a whole is therefore symmetric with respect to these outcomes (if we consider any two outcomes, the probability is the same). However, if the system is sampled (i.e. if the system is actually used or interacted with in any way) a specific outcome must occur. Though we know the system as a whole is symmetric, we also know that it is never encountered with this symmetry, only in one specific state. Because one of the outcomes is always found with probability 1, and the others with probability 0, they are no longer symmetric. Hence, the symmetry is said to be spontaneously broken in that theory.

This mechanism is the basis for the unification of the three forces in Nature; electromagnetism,weak force, strong force. According to this view, and my understanding  the laws of physics that we experience are just an outcome of a random choice. There were other possibilities for this world; for example a possibility that the strong force is not so strong to hold the nucleus of the atoms together. In this case life, as we know it, is not possible. If you take this idea a little more further you can easily assume that there can be worlds that they are completely different from this one. These worlds cannot develop the same chemistry that our life is based on, but nothing forbids them from developing some other kind of life which we cannot even imagine.

I was reading the following post about the fine-structure constant;

the observer effect

fine-structure constant variation; If confirmed, this revelation could reshape physicists’ understanding of cosmology from the ground up. It may even help solve a major conundrum: Why are all the constants of nature perfectly tuned for life to exist?

As you can see the writer thinks that we are very very lucky that we live in a ‘place’ that is “life friendly”. I will not comment on the tautology of the view, but I am surprised that people are interested in science just to find the same answers rephrased; We know that we are here and this is the mystery, we want to know why and how. Learning again that we are here because the laws of Nature are ‘so well tuned’ does not add any kind of knowledge and does not answer something more! Maybe people like to think in this way because they just love to be reminded that they are special nothing more.