Thread: m theory

I like to consider m theory (evolution of string theory) as as close to fact as any other theory can be said to be because from what I read it seems pretty solid.

Would someone with perhaps a more informed opinion like to shed light on any shortfalls of the theory or is it pretty accepted?

I find particularly interesting the concept that our universe is proposed to be a 2dimensional string yet from what I understood they claim to have observed strings with dimensions all the way up to 9 I believe it was. Makes you wonder, if a 2d string makes a universe, what does a 9d string make

Originally Posted by somfooleishfool

I like to consider m theory (evolution of string theory) as as close to fact as any other theory can be said to be because from what I read it seems pretty solid.

Would someone with perhaps a more informed opinion like to shed light on any shortfalls of the theory or is it pretty accepted?

I find particularly interesting the concept that our universe is proposed to be a 2dimensional string yet from what I understood they claim to have observed strings with dimensions all the way up to 9 I believe it was. Makes you wonder, if a 2d string makes a universe, what does a 9d string make

The biggest open problem im M Theory is "What is M Theory ?".

The popular literature is extremely misleading.

Originally Posted by DrRocket

Originally Posted by somfooleishfool

I like to consider m theory (evolution of string theory) as as close to fact as any other theory can be said to be because from what I read it seems pretty solid.

Would someone with perhaps a more informed opinion like to shed light on any shortfalls of the theory or is it pretty accepted?

I find particularly interesting the concept that our universe is proposed to be a 2dimensional string yet from what I understood they claim to have observed strings with dimensions all the way up to 9 I believe it was. Makes you wonder, if a 2d string makes a universe, what does a 9d string make

The biggest open problem im M Theory is "What is M Theory ?".

The popular literature is extremely misleading.

i guess then i refine my question. is it reasonable believe that our universe is a 2d string and that all elementary particles are 1d strings

Originally Posted by somfooleishfool

Originally Posted by DrRocket

Originally Posted by somfooleishfool

I like to consider m theory (evolution of string theory) as as close to fact as any other theory can be said to be because from what I read it seems pretty solid.

Would someone with perhaps a more informed opinion like to shed light on any shortfalls of the theory or is it pretty accepted?

I find particularly interesting the concept that our universe is proposed to be a 2dimensional string yet from what I understood they claim to have observed strings with dimensions all the way up to 9 I believe it was. Makes you wonder, if a 2d string makes a universe, what does a 9d string make

The biggest open problem im M Theory is "What is M Theory ?".

The popular literature is extremely misleading.

i guess then i refine my question. is it reasonable believe that our universe is a 2d string and that all elementary particles are 1d strings

no

That is not what M-Theory states anyway; IIRC M-theory just states that each fundamental string has an emergent string partner- kind of like in a metal composed of protons, neutrons and electrons where a sound wave passing down the metal has a particle partner (predicted by quantum theory) called a phonon. The fundamental and emergent strings are opposite in their actions, for example: if the probability for 2 fundamental strings to interact is proportional to the string coupling constant g, then in some cases the probability for the emergent strings to interact is proportional to 1/g. However, as DrRocket stated, one of M-theory's major problems is that no one actually has a formal (or informal for that matter) definition of what exactly it is; not even Edward Witten (the founder of so called M theory). It is just an "11-dimensional superstring theory".

Originally Posted by x(x-y)

That is not what M-Theory states anyway; IIRC M-theory just states that each fundamental string has an emergent string partner- kind of like in a metal composed of protons, neutrons and electrons where a sound wave passing down the metal has a particle partner (predicted by quantum theory) called a phonon. The fundamental and emergent strings are opposite in their actions, for example: if the probability for 2 fundamental strings to interact is proportional to the string coupling constant g, then in some cases the probability for the emergent strings to interact is proportional to 1/g. However, as DrRocket stated, one of M-theory's major problems is that no one actually has a formal (or informal for that matter) definition of what exactly it is; not even Edward Witten (the founder of so called M theory). It is just an "11-dimensional superstring theory".

In 1995 there were 5 competing string theories: Type I string theory, Type IIA string theory, Type IIB string theory, heterotic SO(32) theory, and heterotic E8×E8 theory. Witten gave a plausibility argument suggesting that these five string theories are related via notions of duality and could be considered as just different aspects of a single theory, called M theory.

No one has ever produced the relationships that connect the five theories, and the very existence of M theory remains an open conjecture.

I actually did know this . I watched on youtube an interview on the guy who had to give a speech after Witten had just announced this and he was real bummed because of how big of a shadow Witten had just made haha.

Originally Posted by somfooleishfool

I actually did know this . I watched on youtube an interview on the guy who had to give a speech after Witten had just announced this and he was real bummed because of how big of a shadow Witten had just made haha.

It was a pretty famous speech by Witten, a lot of physicists reckon it lead to the "2nd Superstring theory revolution". However, the speech itself was not groundbreaking- all Witten said was that "there is a way to unify the 5 fundamental theories within superstring theory" (or something along those lines), he didn't actually come up with any ideas to how this would happen- he just stated it, and everybody jumped on the bandwagon.

In my view, this whole string theory thing has been a bit of a mess within physics- stooping down to the level of imagining things and "creating" extra dimensions whilst fiddling with free constants to try to make the theory fit with any observations and current accepted theories (such as GR). That's not the way physics should work, there has to be some sort of experimental and observational basis to put the theories on- rather than the opposite way around, as has been in a lot of cases with string theory. String theory has had virtually no experimental testing/analysis and so is incredibly unreliable- yet the devout string theorists hold onto it claiming that it "must be right as it is so beautiful"; that's how pseudoscientists speak, not proper scientists, and this sort of attitude should never be had in the field of theoretical physics especially.

Anyway, who knows? String theory could end up being correct, but as far as I'm concerned the evidence points in the opposite direction. I'd even go as far to say that string theory has "prohibited" the revolution of theoretical physics- before the 1980s it was ablaze with new discoveries and had truly been a revolution for 200 years or so, now it is a slowly advancing field with little progress every decade. So, I think physicists (and I plan to become one) should be more careful in years to come as not to get "stuck" on a particular theory because it feels right for them; other possibilities must also be taken into consideration- for example, quantum technicolour theory or loop quantum gravity; however unlikely they may seem to be to start off with, work must be done on each of these contenders for "the theory of everything" in order to gain some more insight into what vital things, in these theories, that we're actually looking for.

Originally Posted by x(x-y)

Originally Posted by somfooleishfool

I actually did know this . I watched on youtube an interview on the guy who had to give a speech after Witten had just announced this and he was real bummed because of how big of a shadow Witten had just made haha.

It was a pretty famous speech by Witten, a lot of physicists reckon it lead to the "2nd Superstring theory revolution". However, the speech itself was not groundbreaking- all Witten said was that "there is a way to unify the 5 fundamental theories within superstring theory" (or something along those lines), he didn't actually come up with any ideas to how this would happen- he just stated it, and everybody jumped on the bandwagon.

In my view, this whole string theory thing has been a bit of a mess within physics- stooping down to the level of imagining things and "creating" extra dimensions whilst fiddling with free constants to try to make the theory fit with any observations and current accepted theories (such as GR). That's not the way physics should work, there has to be some sort of experimental and observational basis to put the theories on- rather than the opposite way around, as has been in a lot of cases with string theory. String theory has had virtually no experimental testing/analysis and so is incredibly unreliable- yet the devout string theorists hold onto it claiming that it "must be right as it is so beautiful"; that's how pseudoscientists speak, not proper scientists, and this sort of attitude should never be had in the field of theoretical physics especially.

Anyway, who knows? String theory could end up being correct, but as far as I'm concerned the evidence points in the opposite direction. I'd even go as far to say that string theory has "prohibited" the revolution of theoretical physics- before the 1980s it was ablaze with new discoveries and had truly been a revolution for 200 years or so, now it is a slowly advancing field with little progress every decade. So, I think physicists (and I plan to become one) should be more careful in years to come as not to get "stuck" on a particular theory because it feels right for them; other possibilities must also be taken into consideration- for example, quantum technicolour theory or loop quantum gravity; however unlikely they may seem to be to start off with, work must be done on each of these contenders for "the theory of everything" in order to gain some more insight into what vital things, in these theories, that we're actually looking for.

thank you, this is really what I was after when I posted my question

It's a pleasure to be of help!

In all honesty, actually, it is not just M-Theory which doesn't have a formulation or definition, it is all of the string theories out there. Here is an extract from a book called "The Trouble with Physics" written by Lee Smolin which I find to be very telling of string theory and I very much agree with it:

Let's begin by recapping exactly what we know about string theory. There is, first of all, no complete formulation of it. There is no accurate proposal for what the basic principles of string theory are, or for what the main equations of the theory should be. Nor is there proof that such a complete formulation exists. What we know of string theory consists mostly of approximate results and conjectures...