String Theory

[Mercedes Benzene]

What does everyone think about string theory?

To me at least, I think the whole idea of String Theory is intriguing, but I have a hard time buying into it.

Also, does anyone have any outrageoud ideas for a "theory of everything". Sometimes I talk to people and they come up with some pretty interesting ideas for an "everything" theory. I just wanted to get an idea about what people here think.

[Jay-qu]

Yeah its all very interesting stuff and all I keep hearing is that the maths of it is far beyond us, so that all we can do is approximate.. but I havent even got a look at it yet :) anyone know any string equations? come on blow my mind :eek:

[alexander]

http://www.superstringtheory.com/basics/basic4a.html

there are some equations there for you too, Jay...

[Jay-qu]

Thats cool :xx: The first few are familiar.. but then it goes downhill

[Tormod]

Basically, string theory is very interesting but AFAIK it has yet to produce any predictions...

[Farsight]

I like the way String Theory moves us away from point particles, and brings higher dimensions into play. OK it doesn't always paint a picture that is easy to get a handle on, but I'm more satisfied with the concepts than those offered by the Standard Model of particle physics.

 

Are we sharing concepts here?

 

My own concept is that point particles involve intractable mathematical infinities, and messenger particles for things like Gravity have to be a red herring because they contradict General Relativity. So it's better to think of particles as "regions of space with properties". Then you can think of these regions of space as having their particular properties because of space being stretched or compressed, or bent or folded or knotted or creased. There's a natural link-up between particle physics where we're talking about small regions of space, and gravity, where we're talking about large regions of space.

 

Anyhow. By creased I mean like the creases down your trousers or round the bottom turnups of your jeans. These creases are the strings. They aren't "made" out of anything other than space. You can't take the creases out of your trousers and hand the creases over to me. And they're creases in more dimensions than we can see directly, and like the Flatlander creases experienced by Mr Square, we experience them as forces. Which rings so true compared to Einstein and Gravity.

 

OK, maybe String Theory (or "M" theory) has some way to go and might evolve or change or be renamed as Ten-Space Topology or something. I'm not sure. But I'm definitely interested.

[Mercedes Benzene]

You make some good points Popular.

To me, it's just soo incredibly hard to comprehend anything that does not have any physical proof whatsoever.

String Theory is especially hard because I suppose I do not fully understand what scientists mean by string theory?? I don't know. haha.

[Farsight]

It takes a while to get a grip on these string, Mercedes. Search Google and you find stuff like this:

 

http://library.thinkquest.org/27930/stringtheory1.htm

 

"For reasons that will later become apparent, the universe seems to incorporate closed strings, although open strings may also be present. Recent research has also revealed that "strings" may actually have many different dimensions, from the one-dimensional strings originally postulated to a two-dimensional membrane to many analogous structures in higher dimensions. Physicists have taken to calling strings "branes," and defining each's dimensional extent with a number, i.e a one-brane is a one-dimensional string..."

[TheFaithfulStone]

You'd like Kaluza-Klein and Heim Theory.

 

Heim Theory is bunk, but it's got one of those "duh" moments that so important to great breakthroughs.

 

I'm not up on my string theory, but it borrows the idea of a compactified dimension from KK.

 

TFS

[docbill]

What does everyone think about string theory?

To me at least, I think the whole idea of String Theory is intriguing, but I have a hard time buying into it.

Also, does anyone have any outrageoud ideas for a "theory of everything". Sometimes I talk to people and they come up with some pretty interesting ideas for an "everything" theory. I just wanted to get an idea about what people here think.

 

The problem with string theory is it is not really a predictive theory. Basically, it is like fitting a polynomial to data. No matter how much data you collect, you can always find a polynomial that fits. The only predictive power comes in assuming you have enough terms in your polynomial. String theory is remarkably successfull, in that it yeilds what appears to be the natural form you need to fit high energy physics observations. Mathematically though it is a nightmare, in that you have to use intuition to subtract infinities to come up with constant values. Those "constant" values are what allows the theory to fit practically anything we experimentally observe. I think of it more as a form of mathematically day dreaming then actually calculating results.

 

Bill

[docbill]

You'd like Kaluza-Klein and Heim Theory.

 

Heim Theory is bunk, but it's got one of those "duh" moments that so important to great breakthroughs.

 

I'm not up on my string theory, but it borrows the idea of a compactified dimension from KK.

 

TFS

 

I am not sure why you would conclude Heim Theory is bunk. The problem with Heim Theory is that it is not based on anything that adds to our understanding of the Universe. Albert Einstein did not just postulate the metrics for general relativity, and say that we now understand gravity. No, he observed the universe and came up with a set of equivalence princables. From those basic princables he derived the metric tensor we know in love. When I am faced with a physics problem, I always start from the basic postulates in order to setup the problem. Without them I am lost and have no way of knowing if my results are reasonable.

 

I have been searching, but I still have not come-up with any of the basic equivalence princables that lead to Heim theory. (I have found some basic princables of Heim theory, but that is not the same thing.) The theory could be right, but without those princables it is no more than a set of equations grabbed from the air. In order for physicists to take the theory seriously, someone will need to figure out what basic princables lead to Heim theory. Given those princables the challenge will be to prove the princables to support the theory.

 

Super String Theory on the otherhand is based on some basic princables. While our ability to grind those princables into firm predictions that can be experimentally tested have been dismal at best, most comologists and high energy physists believe ultimately the theory will be tested by experiment.

 

Interestingly enough, it is not a question of "which theory is correct?" It could well be that both Heim Theory and Super String Theory are correct, each giving access to a different level of details. Or it could be that both are wrong. Given the mathematical form of General Relativity, I have to believe that no matter which unified theory is correct that there is a correct formula very much like Heim theory. However, the only solid reason I would have for believing Heim stumbled on the correct ones is the accuracy of the mass calculations. Even then, I am not convinced tho neutrino calculations are correct leading me to believe at least one term in the equation is wrong.

 

Bill

[Qfwfq]

Mathematically though it is a nightmare, in that you have to use intuition to subtract infinities to come up with constant values. Those "constant" values are what allows the theory to fit practically anything we experimentally observe. I think of it more as a form of mathematically day dreaming then actually calculating results.

Infinities must also be subtracted in RQFT and yet it has been used for decades to calculate many things, many of which have been measured.

[docbill]

Infinities must also be subtracted in RQFT and yet it has been used for decades to calculate many things, many of which have been measured.

 

Physists frequently do things that aren't mathematically correct, because they work. Eventually the mathematicians catchup and formulize why it works. This is never a desired state, as you never know what missing details are important. But sometimes it is a neccessary evil. I just get very uncomfortable when I go to a talks and ask the top experts how he knows something and they admit it is just a guess.

[cwes99_03]

The problem with string theory is it is not really a predictive theory. Basically, it is like fitting a polynomial to data. No matter how much data you collect, you can always find a polynomial that fits. The only predictive power comes in assuming you have enough terms in your polynomial. String theory is remarkably successfull, in that it yeilds what appears to be the natural form you need to fit high energy physics observations. Mathematically though it is a nightmare, in that you have to use intuition to subtract infinities to come up with constant values. Those "constant" values are what allows the theory to fit practically anything we experimentally observe. I think of it more as a form of mathematically day dreaming then actually calculating results.

 

Bill

Sounds like a mistake that every first year student makes when they are taught to fit equations to graphed data.

They always try a 7 or eight term poly to get an equation that matches their data 99% but then when asked to tell me what each of those terms represents they're like "ummmm, what do you mean?"

[docbill]

Sounds like a mistake that every first year student makes when they are taught to fit equations to graphed data.

They always try a 7 or eight term poly to get an equation that matches their data 99% but then when asked to tell me what each of those terms represents they're like "ummmm, what do you mean?"

 

Not quite. When you ask a theorist what each of the integrals/sums means he can give you a precise answer. But when you ask why he matched the terms he did prior to summing, the best he can answer is that it gave him the right answer.

[HappytheStripper]

Imagine the universe as "nothing" .. an eye of a needle .. that knows everything and is self aware .. totally within itself .. no interfacing .. just a dot .. a pinpoint .. under pressure .. a matter of thought creating mass ..

 

Then within a trillionth of a trillionth of a second .. the pressure becomes to much and the eye of the needle begins to open .. allowing enough room for a piece of string to be pulled through .. and a new awareness of a self .. interfacing ..

 

Now imagine the string represents plasma .. a cell like structure and a set of codei .. instructions for a universe .. what do you have .. recipe ..

 

Now what do you think .. ??

 

Man jumped through the eye of a needle .. how did he do it .. ??

 

Why he did it in the blink of an eye .. just one thought and a piece of string .. !!!!

 

Regards Ashley