Huge hole in the sky — WMAP cold spot

Posted in Cosmology, Physics, Science on August 26, 2007 by Christine

The technical paper is here.

Let’s trim them: publish or perish!

Posted in Papers, Personal View, Philosophy, Physics, Science on August 24, 2007 by Christine

From a discussion on plagiarism over at Woit’s blog, came out an interesting spin-off discussion. I will not make a guess on what led those people to plagiarism, nor offer suggestions on how to improve the system, but from the comments that I read, there are certain general issues that are difficult to deny:

1- Science is now a highly competitive field (no longer practised by some few enthusiasts)
2- Publish-or-perish system (the present solution to trim the excess from #1)

I believe such a state of affairs will/is make/ing an imprint to science which, although is not enough to hinder the scientific activity in certain areas and for a certain amount of time, is more than enough to obstruct the pathway for new ideas and originality and ponderation. These, along with hard work, are the genuine ingredients for the advancement of science when at the edge of knowledge.

Hence, #1 and #2 are very worrisome and perturbing items, at least in my view. I would very much like to learn argumentations against those very basic statements.

Galaxies and Dark Matter Apart

Posted in Cosmology, Physics, Science on August 23, 2007 by Christine

Dark matter mystery deepens in ‘train wreck’ –”(…) a mass peak without galaxies [which] cannot be easily explained within the current collisionless dark matter paradigm” (see technical preprint here).

Update: Follow this link for an excellent description of the situation in Abell 520.

Can you solve it?

Posted in Mathematics on August 18, 2007 by Christine

Rubik’s Cube has approximately 43 quintillion possible configurations (that’s about $10^{19}$). Daniel Kunkle can solve it in 26 moves.

Are you looking for God?

Posted in Personal View, Philosophy, Science on August 17, 2007 by Christine

I have received the following comment to my previous blog entry:

Dear Christine,

Have you considered that you may actually be looking for God ?
There are strong indications in your poetry and blogging.

I wish you only the best,

Denis

I have decided to answer to Denis in a separate post. Here is my answer.

Dear Denis,

Well, I have intensively looked for God as a child and did not find him. But the notion of “God” have many meanings. Maybe I have searched in the wrong place. In any case, the fact is that I gave up on any kind of God ever imagined on the face of Earth for a long time. I have no religion whatsoever.You say that “there are strong indications in your poetry and blogging” that I am looking for God. I don’t know what is your notion of God. But yes, I can tell you for sure that I *am* looking for something.

First, I am looking for a scientific understanding of observed phenomena in nature, how the universe came into its present state, a description of the fundamental interactions and particles, why their properties are the way the are, etc. (Yes, all that is too much. I’ll never know in my lifetime. I am just a curious person). I think we have learned a lot about all these issues, but at the same time I also think that we are very far from having a complete understanding of them. I am firm to my belief that the scientific method is the only way to probe those questions at our current state of intellectual and technological development. But at the same time, I do not know whether those questions have an ultimate answer. Would an ultimate answer be God? You may call it that, if you like.

Second, as I mentioned, the scientific method serves us very well at our current state of development. Physical laws described as mathematical equations are the most beautiful “miracle” that our human mind has perceived. But I have a deep, wild, abstract feeling and absolutely non-scientific intuition that there is a sense in which the universe, its existence (and our existence), has a much stranger, impenetrable, mysterious status that we really may never be able to conceive. Would such a mysterious status be God? You may call it that, if you like.

Why I am here?

It’s a cry in the vast, empty desert of existence and there is not even an echo in response. Would the lack of an echo be God? You may call it that, if you like.

Best regards,
Christine

Living in a simulation? Much stranger than that.

Posted in Personal View, Philosophy, Science on August 15, 2007 by Christine

Here are my ramblings on this. [Via Woit's blog].

First, if the universe is a “simulation”, then there must necessarily be some kind of “reality out there” (inaccessible to us, who are part of the simulated elements and imposed rules) that put the simulation to run, to begin with.

Conversely, the “reality out there” must have access to the simulation, otherwise there would be no purpuse of running the simulation, to begin with.

These initial considerations, which reveal an obvious asymmetry, lead however to the following: even if the simulation has “nothing to do” with the “reality out there” (e.g., I can run on my laptop right now models which have nothing to do with the observed nature), there must be a minimum “concordance”, or a minimum “set of rules or elements”, or a minimum “translation map” between the simulation and the “reality out there”, in order to make simulation meaningful in some sense to the “reality out there”-guys.

Then, what would those minimum “concordance” elements, rules, or whatever be? If we could know them, we could end up learning at least a bit about the “reality out there” and my first assertion above would not be entirely true (namely, that the “reality out there” is inaccessible to us).

The only thing I can imagine is the following. The universe as we (very partially) know it gave rise to conscious beings like us, who are now asking exactly whether the universe is a simulation. This is a loophole; mathematics is another one. We have a mathematical mind and nature does obey general physical laws written in mathematical language. (This doesn’t imply of course that we live in a simulation, but if we did, I think these loopholes would seem to serve well to the minimum “concordance” elements between “both worlds”).

But what is the probability that the universe is a simulation?

I don’t really think such a question makes sense. But yet if one is willing to push it ahead anyway, I would say that an indication of such a probability would come from a complete, unequivocal proof that there is no ultimate reality, independent of the observer. If this could be somehow proved (1), then I would state that the probability that the universe is a simulation would be non-zero. (What? You wanted more precision than that?)

I personally believe that everything is much stranger than all that. I have no way to envision; if I did, it would not be strange enough.

(1) I don’t think we can prove it, and perhaps it is impossible to prove it. And although quantum mechanics currently points to that direction, I don’t think quantum mechanics is correct in an absolute or ultimate sense.

Cha-Cha-Cha!

Posted in Philosophy, Science on August 15, 2007 by Christine

The Cha-Cha-Cha Theory of Scientific Discovery (by Daniel E. Koshland Jr), in Science 10 August 2007, Vol. 317. no. 5839, pp. 761 – 762.

In looking back on centuries of scientific discoveries, (…) a pattern emerges which suggests that they fall into three categories–Charge, Challenge, and Chance–that combine into a “Cha-Cha-Cha” Theory of Scientific Discovery.

• “Charge” discoveries solve problems that are quite obvious–cure heart disease, understand the movement of stars in the sky–but in which the way to solve the problem is not so clear.
• “Challenge” discoveries are a response to an accumulation of facts or concepts that are unexplained by or incongruous with scientific theories of the time.
• “Chance” discoveries are those that are often called serendipitous and which Louis Pasteur felt favored “the prepared mind.”

It’s a reasonable list, but I fear that future generations may get used to the idea that scientific discovery could also be classified by one more “cha”:

• “Champion” discoveries: those which are claimed to be correct from having defeated or surpassed all “rivals” in a “competition” which nevertheless has nothing to do with the traditional scientific method of evaluation.

Cha-Cha-Cha-Tchau!

(“Tchau” translates to “bye” in Portuguese).

Is the Planck Scale Geometry in LQG Discrete or Not?

Posted in Physics, Quantum Gravity, Science on August 14, 2007 by Christine

A new paper by Bianca Dittrich and Thomas Thiemann scrutinizes the “celebrated results of Loop Quantum Gravity” (LQG) that state that geometrical operators like area, volume, etc, have discrete spectra.

Are the spectra of geometrical operators in Loop Quantum Gravity really discrete? (Bianca Dittrich & Thomas Thiemann) [http://arxiv.org/abs/0708.1721]

Abstract: One of the celebrated results of Loop Quantum Gravity (LQG) is the discreteness of the spectrum of geometrical operators such as length, area and volume operators. This is an indication that Planck scale geometry in LQG is discontinuous rather than smooth. However, there is no rigorous proof thereof at present, because the afore mentioned operators are not gauge invariant, they do not commute with the quantum constraints. The relational formalism in the incarnation of Rovelli’s partial and complete observables provides a possible mechanism for turning a non gauge invariant operator into a gauge invariant one. In this paper we investigate whether the spectrum of such a physical, that is gauge invariant, observable can be predicted from the spectrum of the corresponding gauge variant observables. We will not do this in full LQG but rather consider much simpler examples where field theoretical complications are absent. We find, even in those simpler cases, that kinematical discreteness of the spectrum does not necessarily survive at the gauge invariant level. Whether or not this happens depends crucially on how the gauge invariant completion is performed. This indicates that “fundamental discreteness at Planck scale in LQG” is an empty statement. To prove it, one must provide the detailed construction of gauge invariant versions of geometrical operators.

A Real Scientist at Heart

Posted in Personal View, Physics, Science on August 12, 2007 by Christine

Oh, I went through this many times before. But here is a plain commentary by an anonymous over at Woit’s blog that is worthy to dedicate a separate post to. He/she writes:

A wise professor once told me that there are the real scientists and then there are the politicians. (And he was talking about those with Ph.D.’s in the sciences.) I think his statement holds true for these people regardless of their career choice, whether they’re actually engaging in scientific research or not. A real scientist at heart will have great respect for truth over ego, period. Though he/she, with human weaknesses and all, may not be perfect all the time, his/her true desire nevertheless will be clear over time.

Science is a pure and uplifting endeavour, but a human activity anyway. Fascination and curiosity (modulated by a highly technical and logical training) in their purest forms are often disturbed by waves of destructive elements like ego.

(Hmm. Perhaps there is an explanation why I like Star Trek’s Spock so much).

Dyson’s Heretical Thoughts

Posted in Philosophy, Physics, Science on August 10, 2007 by Christine

[Via Edge]:

As a scientist I do not have much faith in predictions. Science is organized unpredictability. The best scientists like to arrange things in an experiment to be as unpredictable as possible, and then they do the experiment to see what will happen. You might say that if something is predictable then it is not science. When I make predictions, I am not speaking as a scientist.

Freeman Dyson