the String Theory

dr wu23 wrote: Just curious......has there been any actual testing of this theory on a practical level via colliders or the like that show there's any merit to the theory..?

No, this is one of the problems, string theory is not testable with our current technology, and not just by a small margin but by orders of magnitude. It is highly unlikely that we can ever achieve the energies required to probe strings processes. Scientists have been trying to find ways in which it could be possible to get some indirect testing of the theory at lower energies but so far have not found any viable experiment.

Equality 7-2521 wrote: Yes, of course. I doubt our prospects to test the hypothesis anytime in the near future though, and it makes me question that strategy to channel an overwhelming majority of funding into string theory at the loss of alternative unification theories when such an ability is lacking.

Fully agree, have you read the book by Peter Woit 'Not Even Wrong'? if you work in string theory I'd say it's a must read.

Equality 7-2521 wrote: I have not. I did read Smolin's The Trouble with Physics. Does it add anything to the argument made there? It's a bit ingenuous to say I work in string theory. I'm a pure mathematician whose research happens to be related to string theory / high energy physics.

I have read 'The Trouble With Physics' too, nice one, I like Lee Smolin, I just ordered his 'Time Reborn' and I look forward to reading it.

I voted for 'yes, it's interesting', although no I don't really like it. There's been a long time tug of war between whether a unified field theory will look more like relativity or more like quantum mechanics. Quantum mechanics has been winning out more often than not, though it still fails to seal the deal. Personally I think particles are particles not strings. They exist in space that is curved and wavy. The particles take on properties of waves because they travel through wavy space. Finally, I expect that a unified field theory will be more like relativity than quantum mechanics in the end. I'm not a physicist.

Gerinski wrote: HackettFan wrote: I voted for 'yes, it's interesting', although no I don't really like it. There's been a long time tug of war between whether a unified field theory will look more like relativity or more like quantum mechanics. Quantum mechanics has been winning out more often than not, though it still fails to seal the deal. Personally I think particles are particles not strings. They exist in space that is curved and wavy. The particles take on properties of waves because they travel through wavy space. Finally, I expect that a unified field theory will be more like relativity than quantum mechanics in the end. I'm not a physicist. Everything points the other way around though, most physicists believe that General Relativity needs to be quantized. GR does not only describe spacetime but also matter and the way both of them interact, in GR both spacetime and matter / energy are classical (continuous). It is known that matter / energy is quantized, so from this point of view GR is already incorrect. There are some approaches where quantized matter / energy interacts with continuous spacetime but they also present difficulties. Quantum field theory by itself is not devoid of problems either, it is based on a rigid background geometry (that of Special Relativity) when we know that the background geometry is not rigid. So none of both look like real winners, the solution probably needs to be something else altogether.

Yes, relativity needs to be quantized, but quantum mechanics needs to account for gravity. That's exactly the tug of war I was talking about. Physicist tend to learn fundamental things at high energy states, but disagreement occurs as to where high energy states are really found, when things are really large or when they are really small. Quantum mechanics doesn't handle gravity easily, but a lot of physicists are strangely untroubled by this, because they consider it a low energy state. You're probably right that a viable unified field theory will be different from both relativity and quantum mechanics. I, for one, question the the very premise of quantum mechanics though that particles are sometimes particles and sometimes waves (ironically Einstein's own major contribution to quantum mechanics). Particles sometimes have wavelike properties, not because they are waves or wavy strings or whatever, but because they flow through wavy space-time. It's like a ball floating on water. It's motion proceeds in a way that can be graphed or transposed into a wave but it's still a ball. The wave motion is a function of waves occurring in the water not an integral property of the ball. Again, I'm not a physicist, but this makes something rational out of a long standing paradox, which I find incredulous.

Edited by HackettFan - July 31 2013 at 19:20

aginor wrote: what about these issues a) gravitons

Gerinski wrote: aginor wrote: what about these issues [QUOTE=aginor]  I know that a punch (boxing punch) straight can mac be 150 to 400 kgs or more) a boxing punch down can be between 700 to 1200 kgs, because of the pull of gravity, its easier to hit hard with the help of gravitational pull then, punching straight out in the air with gravitation breaking you kinetic force  Where did you read that? I believe that's a misunderstanding. The strength of your hit is the same, but of course the gravitational pull on the punching bag itself makes a difference, if you try to lift it up punching from below, it will be harder than if you try to push it down punching from above.

an episode of fight science about MMA, referring to the force of a punch straight forward and a punch that goes downwards, horizontal punch vs downward punch http://www.youtube.com/watch?v=NMphoz0hNeE 

I am a martial artist so i am very interested in all aspects of martial arts, and force behind what you do, sorry for not interest you with the science of martial arts which is a very precise yet, the results form measuring the science behind kicks and punches, is able to shock physicist who is measuring the scores, so much they have hard time believe what they are seeing on the data screen and monitors.

Gerinski wrote: Gravity is an extremely weak force and it works noticeably only because of its cummulative property. You routinely overcome the gravitational pull of the whole planet Earth every time you lift a coin from the floor. A simple fridge magnet overcomes easily the gravitational pull of the whole planet. With objects smaller than a small planet or moon, gravity is rather negligible.

No, gravity is an extremely strong force dispersed over great distance. It is weak up close but extends much further. If you drop a coin it falls back to the earth a distance so many orders of magnitude greater than what the strong and weak force have any influence over that scientific notation would be needed. If you pick it up you only separate it permanently from the earth only at a distance equal to your reach and by continuously holding it and being immortal like Atlas. And really the coin is still on the earth's surface because we basically still part and parcel of the earth's mass, so it hasn't really been separated from the earth. If you can routinely throw a coin into escape velocity from the surface of the earth that would be a better comparison. Of course, there's no one who can separate a coin from the earth in that more real sense. At large distances we see gravity acquitting itself quite against the strong force throughout the life of a star, and in fact causes the fusion chain reaction to occur in the first place. The idea that gravity is weak is simply a bias many physicist carry with them because they are pre-occupied by a perspective that focuses only on the quantum level as significant. Even if one can't separate themselves from this perspective, consider black holes. Black holes are so "impossibly" small as to have no size (they're a singularity), yet no force can even compete with gravity in that case all the way out to the event horizon.

Gravity is by far the weakest force. It's ability to span distance has nothing to do with its inherent strength.