It is a very interesting theory a "theory of everything" as string theorists like to say. But does having mathmatical backing to the theory make it physics? Or does the fact that there is no way to test it (until the new partical accelerator is built in Italy) make it Philosophy?
String Theory - Physics or Philosophy?
- Thread starter Cawchy87
- Start date
I would say that it's observational physics. Much like before elliptical orbits were found in the solar system, when the motion was believed to be circular. It's merits will be refined, and either thrown away, or adopted.
PowerEngineer
Diamond Member
- Oct 22, 2001
- 3,605
- 785
- 136
This is one of the interesting points discussed in Nova's The Elegant Universe (You can watch all three hours on the PBS website!)
It seems to me that the key difference between science and philosophy (religion) is that conjectures can be put to the test against reality -- and that this testing is never ending (as shown by recent experiments to verify predictions of relativity). Some people have suggested that the nature of string theory makes it impossible to test (i.e. it's a complete description of everything we already know without predicting anything measurable that we don't know). If so, then it would seem to be indistinguishable from philosophy. As string theory is fleshed out, I'm hoping that its proponents will discover ways to test it against reality and therefore prove it to be a theory of science (mind you, not necessiarly a completely correct theory).
Here's part of one interview from the PBS website:
NOVA: What would it take, do you think, to prove or confirm that string theory is right?
Peet: You can never prove that a theory of nature is correct. All you can prove is that it's the best theory you have that satisfies your theoretical consistency and describes the real world to the accuracy that we can test it. I'm not sure if we'll ever know whether a particular theory is the truth, because physics is an operational science. What we do is experiments, and we check our theoretical predictions against our experimental results. Once we've come up with a theory that agrees with the experimental results, we then try to predict something new that we haven't measured before. That's the process by which we keep refining our theories of nature.
It is always easier to falsify a theory than to prove it's correct. String theory, as yet, can't be falsified, partly because it is such a big structure. It's got so many ideas in it and incorporates so many new concepts, like extra dimensions and supersymmetry and unification, that at the moment, string theory is a flexible enough structure that it cannot be falsified.
NOVA: Then how do you respond to critics who say, "This is just not testable. It's not science."
Peet: String theorists worry a lot about whether our approach to understanding all of the forces and unification is the right track to be following. I think the best justification at present is that it's really, by far, the best approach to trying to understand the quantum theory of gravity. It's certainly better than taking Einstein's general relativity theory and trying to kludge it together with the standard model]. Just taking general relativity and the standard model, which is a quantum theory, doesn't enable you to calculate anything in extreme regimes deep inside black holes or back at the origin of the universe.
So it's the best we've got. And if it turns out that a part of it is not really the right way to be proceeding, what we'll find is that we'll need to add extra ideas or change our attack somewhat. But as scientists, all we can really do is work with the best theory that we've got and keep refining it as the experimental data keep coming in.
NOVA: How do you examine string theory experimentally?
Peet: Since string theory is a theory of extremely high-energy physics, one of the concerns one might have as a string theorist is: how will we really be able to give this theory a good run for its money and really test it out? The traditional way that high-energy physicists have tested theories is to make predictions about what happens in particle accelerators, because that was the most direct way that we could really crank up to very high energies and test our theories. So we can expect string theory and its predictions for low-energy physics to be tested inside accelerators. That's one of the reasons why string theorists are waiting keenly for what's going to come out of Run II at Fermilab and what happens at the Large Hadron Collider when it's finally up and running. [Editor's note: Run II at Fermilab began in March 2001. The Large Hadron Collider is now under construction at CERN on the Franco-Swiss border near Geneva.]
But there is another way of trying to test predictions of string theory, or whatever else might be the final theory describing the highest-energy physics that we can imagine. What that takes advantage of is the fact that the highest energies ever were in the big bang. So it's natural to try to take advantage of that cosmic experiment, even though there was only one experiment.
One of the ways that you can test theories of cosmology is to look at the background radiation that's left behind from the big bang. This is called the cosmic microwave background. It's currently very cold radiation, but back when the big bang was happening, it was extremely hot. It's thought that what was happening back at the big bang, or somewhat later, could imprint on that radiation that then came to us, eventually, as this very cold radiation.
There have been some experiments done already in cosmology that are really producing fantastic data, providing very precise measurements of not only the background radiation itself, but the fluctuations in that background radiation. For example, maybe the temperature in that region of the sky is a little bit colder than the temperature over there. People have been very carefully analyzing those little differences in the background radiation all over the sky to try to tell us about what was happening back much closer to the big bang.
This is really the decade of cosmological data. There are fantastic experiments that have already happened, and there are even more precise ones that are going to be bringing in data very soon. We've already got, from cosmological data, some very interesting information about the universe and the stuff that's in it that has really shaken up the string theory community, in terms of the ways that we try to build models of the real world.
It seems to me that the key difference between science and philosophy (religion) is that conjectures can be put to the test against reality -- and that this testing is never ending (as shown by recent experiments to verify predictions of relativity). Some people have suggested that the nature of string theory makes it impossible to test (i.e. it's a complete description of everything we already know without predicting anything measurable that we don't know). If so, then it would seem to be indistinguishable from philosophy. As string theory is fleshed out, I'm hoping that its proponents will discover ways to test it against reality and therefore prove it to be a theory of science (mind you, not necessiarly a completely correct theory).
Here's part of one interview from the PBS website:
NOVA: What would it take, do you think, to prove or confirm that string theory is right?
Peet: You can never prove that a theory of nature is correct. All you can prove is that it's the best theory you have that satisfies your theoretical consistency and describes the real world to the accuracy that we can test it. I'm not sure if we'll ever know whether a particular theory is the truth, because physics is an operational science. What we do is experiments, and we check our theoretical predictions against our experimental results. Once we've come up with a theory that agrees with the experimental results, we then try to predict something new that we haven't measured before. That's the process by which we keep refining our theories of nature.
It is always easier to falsify a theory than to prove it's correct. String theory, as yet, can't be falsified, partly because it is such a big structure. It's got so many ideas in it and incorporates so many new concepts, like extra dimensions and supersymmetry and unification, that at the moment, string theory is a flexible enough structure that it cannot be falsified.
NOVA: Then how do you respond to critics who say, "This is just not testable. It's not science."
Peet: String theorists worry a lot about whether our approach to understanding all of the forces and unification is the right track to be following. I think the best justification at present is that it's really, by far, the best approach to trying to understand the quantum theory of gravity. It's certainly better than taking Einstein's general relativity theory and trying to kludge it together with the standard model]. Just taking general relativity and the standard model, which is a quantum theory, doesn't enable you to calculate anything in extreme regimes deep inside black holes or back at the origin of the universe.
So it's the best we've got. And if it turns out that a part of it is not really the right way to be proceeding, what we'll find is that we'll need to add extra ideas or change our attack somewhat. But as scientists, all we can really do is work with the best theory that we've got and keep refining it as the experimental data keep coming in.
NOVA: How do you examine string theory experimentally?
Peet: Since string theory is a theory of extremely high-energy physics, one of the concerns one might have as a string theorist is: how will we really be able to give this theory a good run for its money and really test it out? The traditional way that high-energy physicists have tested theories is to make predictions about what happens in particle accelerators, because that was the most direct way that we could really crank up to very high energies and test our theories. So we can expect string theory and its predictions for low-energy physics to be tested inside accelerators. That's one of the reasons why string theorists are waiting keenly for what's going to come out of Run II at Fermilab and what happens at the Large Hadron Collider when it's finally up and running. [Editor's note: Run II at Fermilab began in March 2001. The Large Hadron Collider is now under construction at CERN on the Franco-Swiss border near Geneva.]
But there is another way of trying to test predictions of string theory, or whatever else might be the final theory describing the highest-energy physics that we can imagine. What that takes advantage of is the fact that the highest energies ever were in the big bang. So it's natural to try to take advantage of that cosmic experiment, even though there was only one experiment.
One of the ways that you can test theories of cosmology is to look at the background radiation that's left behind from the big bang. This is called the cosmic microwave background. It's currently very cold radiation, but back when the big bang was happening, it was extremely hot. It's thought that what was happening back at the big bang, or somewhat later, could imprint on that radiation that then came to us, eventually, as this very cold radiation.
There have been some experiments done already in cosmology that are really producing fantastic data, providing very precise measurements of not only the background radiation itself, but the fluctuations in that background radiation. For example, maybe the temperature in that region of the sky is a little bit colder than the temperature over there. People have been very carefully analyzing those little differences in the background radiation all over the sky to try to tell us about what was happening back much closer to the big bang.
This is really the decade of cosmological data. There are fantastic experiments that have already happened, and there are even more precise ones that are going to be bringing in data very soon. We've already got, from cosmological data, some very interesting information about the universe and the stuff that's in it that has really shaken up the string theory community, in terms of the ways that we try to build models of the real world.
. Thats why i am posting.Peter Woit summarizes my view pretty well in his article "Is String Theory Even Wrong?" in American Scientist.
That is a very good article, just one little bit i would like to put forth:
String Theorists do make one perdiction. In a partical colision they predict that they will "see" a small bit of gravity (a gravitron) seemingly "float" off into another dimention. Granted that we never know if it will be found it is a very small prediction so i would have to mostly agree with the statement above.
I just thought i would be the first physics student to post here. It is a real theory, there is a lot of mathematical evidence, it is still being worked on, it is not proven, it explains a lot about gravity on the planck scale, and it is likely that it will never be completely proven. The thing is, much of what we know comes from deduction based on crude experiments and complex mathematics which are still not entirely understood. We still lack a fundemental principle to guide us. An example of such a principle was Einstein's relativity theories. It's more like working backwards compared to that. But it does help us predict a lot of things about the universe and is therefore very useful, even if it's not right.
i do believe in the string cheese theory: it tastes good when you eat it thanks cawchy for the CoD
Chaotic42
Lifer
- Jun 15, 2001
- 34,778
- 1,953
- 126
Pauli used to say that about things. "It's not even wrong".
There's a way to test string theory, but it requires huge colliders. The US had an $11B supercollider in the works, but it was cancelled. It's not hard to see why, it's very difficult to convince people to spend $11B on something like that.
Anyway, supposedly if you take two elementary particles and make them collide in a certain way, they'll shatter and it's possible that a graviton will form. Being a closed-string particle, it would rapidly fly away. That's what M-Theory predicts anyway.
Edit: Well, it looks like not reading every reply in the thread has failed me again and my post is redundant.
Ah, well. :beer:
Just saying you can't prove something wrong doesn't mean that it is true in any way. I want to believe in the String Theory and I want to do research in it when I get older, but I realize that it all might amount to nothing.
The thing that troubles me most is that the only reason why this theory isn't being screamed at like Galileo's thoery of the heliocentric universe at the time of its conception is because of the apparent equal mathematics behind it. But there are several different ways of representing this, which probably means that we need more information. A lot more information. Theoretical physics always has this conundrum.
As for supersymmetry, where's all the antimatter???
The thing that troubles me most is that the only reason why this theory isn't being screamed at like Galileo's thoery of the heliocentric universe at the time of its conception is because of the apparent equal mathematics behind it. But there are several different ways of representing this, which probably means that we need more information. A lot more information. Theoretical physics always has this conundrum.
As for supersymmetry, where's all the antimatter???
The testability of a theory isn't a matter of technique, it's a matter of logic. Superstring theory is testable in that it makes positive predictions about how the universe works. This is verifiable logically, even if we can never find the technology to do it.
Compare this to the testability of Freud's theories, a classic case of an untestable theory.
"You hate your father"
"No I don't"
"You're in denial"
His theory has rationales built-in that explain away any aberration in the data. There is no way to verify his claims, because there is no way to refute them.
Compare this to the testability of Freud's theories, a classic case of an untestable theory.
"You hate your father"
"No I don't"
"You're in denial"
His theory has rationales built-in that explain away any aberration in the data. There is no way to verify his claims, because there is no way to refute them.
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