Question about M Theory/String Theory

[Buffalo Souljah]

How does string/M theory (I know these are two "variations on a theme", but I don't know much more than that, so correct me if I'm wrong) take account of forces (gravity, electromagnetic, etc.) and "abstract" factors like thought and motor activity (and even things like "free will")? I would like to know, since a theory of everything would certainly have to contain some form of representation of thoughts and events, both abstractly and practically, no? Also, could we use this theory to discover if/when/where alien life exists, or at least what the probability of such a thing would be? I know of some formulas in string theory, and one such formula utilizes a set of integers for which any event (or every event) could stand. Does this play into the same sort of thinking, or am I completely off base? Just curious...

[Cal Engime]

String theory only concerns the physical interactions between particles. It is an attempt to construct a theory which implies both general relativity and quantum mechanics.

Contrary to popular belief, quantum mechanics does not imply that consciousness has a special place in the laws of physics. If it's thought and free will you're interested in, you should be studying neuroscience, not theoretical physics. I recommend A Brief Tour of Human Consciousness by V. S. Ramachandran.

The Drake equation (look it up—I can't post links because of my low post count) can give you an estimate of the number of alien civilisations in our galaxy, but you have to make wild guesses for variables like "number of life-supporting planets per solar system" and "probability that life on a planet becomes intelligent." The number will depend on whose questionable assumptions you trust, but I think it's safe to say that if any aliens exist, they must live so far away that meaningful communication would be impossible. It might be cool to write to a pen pal and get a reply 60 years later, though.

[ComradeRed]

A "theory of everything" is not a literal theory that explains every minute detail like what will happen to me after lunch.

It is a theory that explains all of the forces involved in physics as one "unified" field.

String theory kind of does this...it works with a representation that is broken down as the direct sum of a traceless symmetric rank-2 tensor ("graviton" or quantum gravity), a scalar matrix ("dilaton"), and an antisymmetric rank-2 tensor (generalizing electromagnetism).

It turns out to be consistent, more or less, perturbatively renormalizable, etc.

However, difficulties arise due to Tachyonic strings, ghosts, etc.

[black magick hustla]

To humanize what CR, basically, in physics you have two big scientific paradigms, quantum mechanics, and general relativity. Basically, imagine that in biology you had natural selection and lysenkoism, and that both, although they take contradictory underlying assumptions, can explain different aspects of evolution, and therefore are both "correct". This is the problem with physics, quantum mechanics is really good for explaining everything except gravity. QM assumes force is mediated through bosonic force carriers, which are particles. For example the photon mediates the electromagnetic force. However, gravity, as a force, is better "explained" by GM which explains it as a curvature of space. Physicists have been trying for atleast the last thirty years to Unify both theories so that there aren't contradictory assumptions anymore, therefore the rise of String theory.

[Mumbles]

If you haven't already, I'd recommend reading Brian Greene's "The Elegant Universe". I'm currently reading it and it's a very excellent statement of the history and implications of string-theory as explained in layman's terms.

Also there's a special PBS did that's related to the book, but I haven't watched it so I don't know if it covers exactly the same stuff, but I would figure it would get the same points across, although probably less detailed.

[Buffalo Souljah]

Contrary to popular belief, quantum mechanics does not imply that consciousness has a special place in the laws of physics. How does modern physics view thought, as the byproduct of electromagnetic and chemical interactions? I suppose it would seek a rather "mechanical" understanding of 'thought', as opposed to psychology, theology, neuroscience or biology. Is this adequate, though?


If it's thought and free will you're interested in, you should be studying neuroscience, not theoretical physics. I recommend A Brief Tour of Human Consciousness by V. S. Ramachandran. Is this a book on neuroscience?


The Drake equation (look it up—I can't post links because of my low post count) can give you an estimate of the number of alien civilisations in our galaxy, but you have to make wild guesses for variables like "number of life-supporting planets per solar system" and "probability that life on a planet becomes intelligent." The number will depend on whose questionable assumptions you trust, but I think it's safe to say that if any aliens exist, they must live so far away that meaningful communication would be impossible. It might be cool to write to a pen pal and get a reply 60 years later, though.

Very interesting. Thanks. Fresh from Wikipedia:

he Drake equation is closely related to the Fermi paradox (http://en.wikipedia.org/wiki/Fermi_paradox) in that Drake suggested that a large number of extraterrestrial civilizations would form, but that the lack of evidence of such civilizations (the Fermi paradox) suggests that technological civilizations tend to disappear rather quickly. This theory often stimulates an interest in identifying and publicizing ways in which humanity could destroy itself, and then counters with hopes of avoiding such destruction and eventually becoming a space-faring species. A similar argument is The Great Filter (http://en.wikipedia.org/wiki/The_Great_Filter),[2] (http://en.wikipedia.org/wiki/Drake_equation#cite_note-1) which notes that since there are no observed extraterrestrial civilizations, despite the vast number of stars, then some step in the process must be acting as a filter to reduce the final value. According to this view, either it is very hard for intelligent life to arise, or the lifetime of such civilizations must be relatively short.As T.J. Nelson states:[17] (http://en.wikipedia.org/wiki/Drake_equation#cite_note-16)



The Drake equation consists of a large number of probabilities multiplied together. Since each factor is guaranteed to be somewhere between 0 and 1, the result is also guaranteed to be a reasonable-looking number between 0 and 1. Unfortunately, all the probabilities are completely unknown, making the result worse than useless.
Likewise, in a 2003 lecture at Caltech (http://en.wikipedia.org/wiki/Caltech), Michael Crichton (http://en.wikipedia.org/wiki/Michael_Crichton), a science fiction author, stated:[18] (http://en.wikipedia.org/wiki/Drake_equation#cite_note-17)

The problem, of course, is that none of the terms can be known, and most cannot even be estimated. The only way to work the equation is to fill in with guesses. [...] As a result, the Drake equation can have any value from "billions and billions" to zero. An expression that can mean anything means nothing. Speaking precisely, the Drake equation is literally meaningless...


Sounds very speculative... I don't think I'd trust anyone's calculations as there is not basis on which to rest these, outside mere opinion (even if it is well-informed).

[ÑóẊîöʼn]

All the evidence points towards consciousness being the consequence of strictly physical interactions, even though the precise mechanism is only understood in the vaguest terms. It may be possible to describe consciousness in terms of fundamental interactions, but why would you want to? We know how computers work, but we talk about them in terms of hardware and software, rather than the interactions of electrons, because it would simply be too cumbersome to describe such macroscale objects at such a minute level. I suspect the same may apply for a theory of consciousness, if we ever get round to it.

There is another confounding factor - complex systems such as human brains are not strictly deterministic as far as we can tell, rather they appear to be probabilistic (which means that absolute predictions are ruled out) and also emergent, which means that you can't really tell which way things will turn out once they get going, unless you actually observe the system in action instead of simulating it.

Basically, the universe is a hell of a lot more complicated in it's workings than we originally thought it to be. At least that's my understanding.