Sunday, February 20, 2011

Quote of The Week - Allan Rosenberg

I’m not qualified to evaluate technical issues in string theory, but I can imagine a biologist who submits a paper postulating that lions have sharp canines because there is a multiverse that includes universes with all possible biota, and we happen not to live in a dull-toothed lion universe. I don’t think that would pass peer review. Maybe we biologists are just too closed minded.

Don’t worry, you don’t sound at all like Motl. He has a Czech accent. And you’re FAR funnier than he is.

... Allan Rosenberg to Peter Woit, in the replies at Not Even Wrong,  here

Leonard Susskind in the Lion's Den


Jérôme CHAUVET said...

I've always thought of "multiverse theory" that it is a ridiculous one. Or just equivalent to the assumption that probabilities in quantum theories are there for practical use only.

According to it, quantum systems may not be able to choose between several possibilities so every of them should pertain recurrently in the future, and so on. In my opinion, the universe knows how to choose within the black box between a dead cat and a cat still alive and it's up to our models to model that, not up to the universe to resemble what equations tell.

We simply dare not say quantum theory is in no way reality but is only a model of reality.


Steven Colyer said...

The "Multiverse" theory has many sources, the most current one being the "Anthropic Landscape" in String Theory idea of Leonard Susskind, with his second in command, Joe Polchinski of Kavli, both of whom are brilliant, brilliant men.

This is all explained very well in Peter Woit's book, "Not Even Wrong", so I won't go on any more about it here.

I have studied Anthropic, and found it very, very wanting. The first clue is: "Anthro-" in Anthropic. I.e., "man" or "human-" centered. Trust me, the universe doesn't care if Humanity let alone Earth or Sol exists. The Mandelbrot Set would be what it is if we had never existed. So let's keep "Man", or "life" even, out of this. The Universe is what it is, with or without us. No "Anthro-" about the Universe, we should feel lucky just to be here.

Anthropic comes in 2 flavors: The Weak Anthropic Principle and The Strong Anthropic Principle. I've studied both, and my conclusion is: they're both weak. Why differentiate? Weak is weak.

Which is not to say I have "proof" of these opinions. I have none, and given the subject, neither does anyone else, for it is 100% NON-falsifiable, not just because of the (lack of) technology we have, but because of the lack of technology that is even possible.

In my opinion, as always. But it's not just me.

Upshot: I think "Anthropic" hurts String Theory. If one wishes to learn String Theory, listen to David Gross. I was going to say Ed Witten too, but Witten is playing politics and trying to ford a bridge between the Anthropic camp of Susskind and the Non-Anthropic camp of Gross.

Listen to Gross, would be my advice. Lenny does what he does for whatever reason, and since he's 70, he should have Emeritus status by now, and if he does, Anthropic should have done it for him, but it may be overkill, as he was one of the three men who rescued String Theory from the ashes that was the epic fail that was the Bosonic String Theory of Venezio, The Father of Strings, whose Strings failed to account for matter particles. Lenny was one of the three who introduced Supersymmetry, and that was indeed a great mathematical, if not physical, accomplishment.

Arjen Dijksman said...

Nice modest reply of Allan Rosenberg. I think the biologists are the real physicists of modern times, studying nature itself and not conjectures about nature.

Steven Colyer said...

Oh hello, Arjen, good to see you drop in. Your presence reminds me that I must explore Quantum dots more, as surface physics is one of the many (too many) fields that interests me.

Yes, Allan is modest in a sense, also talking outside his area of expertise a bit, yet with an amusing flair and sweet simple logic that is difficult to assail IMO. I am tempted to call that the Quote of the Decade, possibly more. ;-)

There is a fascinating contrast between Foundational Physics, which seems to be stuck in a highly speculative rut for the moment, and Biology, which thanks to Chemistry thanks to Physics (especially Schrodinger and Pauli) is going absolutely gangbusters.

Also thanks to engineering and the small distances we can probe in a lab. Just great stuff coming out all over the place atm. Who can keep up? Sixty percent of science blogs are biology blogs, wow.

I liked your prime number sieve article at your own blog very much, good thinking. I once spent the better part of the afternoon surfing the netways based on that one post alone.

For other readers, and briefly from Wikipedia, Quantum dots are:

A quantum dot is a semiconductor whose excitons are confined in all three spatial dimensions. Consequently, such materials have electronic properties intermediate between those of bulk semiconductors and those of discrete molecules.They were discovered at the beginning of the 1980s by Alexei Ekimov in a glass matrix and by Louis E. Brus in colloidal solutions. The term "quantum dot" was coined by Mark Reed.

Researchers have studied quantum dots in transistors, solar cells, LEDs, and diode lasers. They have also investigated quantum dots as agents for medical imaging and hope to use them as qubits.