Could you tell me what should I focus on in the provided links? Can you quote?
Concerning the string theory:
wikipedia:
"Not all strings are confined to p-branes. Strings with closed loops, like the graviton, are completely free to move from membrane to membrane. Of the four force carrier particles, the graviton is unique in this way. Researchers speculate that this is the reason why investigation through the weak force, the strong force, and the electromagnetic force have not
hinted at the possibility of extra dimensions. These force carrier particles are strings with endpoints that confine them to their p-branes. Further testing is needed in order to show that extra spatial dimensions indeed exist through experimentation with gravity."
So, existence of extra dimensions can be tested.
I recomend to read:
http://particle-theory.physics.lsa.umic ... 0world.pdf
Some quotes from there:
"Athough string theory is formulated in 10 or 11 dimensions, specific string theory solutions make unambiguous, testable predictions about our four-dimensional universe."
"... string theory provides a framework to address and relate many open questions in particle physics. We know that particles divide into three families exemplified by the electron, muon, and tau, but if we didn't know it, string theory would suggest that families exist and why. If we did not know about forces such as the strong and electroweak forces of the standard model, or the parity violation of the weak interactions, or supersymmetry, or inflation, or gravity, string theory would suggest them."
"Based on the presentation of string theory in some popular books, articles, and blogs, one might well be suspicious of taking purported string theory explanations seriously. Such sources often claim that string theory is not testable, and I agree that untestable explanations are not helpful. But I would also argue that string theory is testable in basically the same ways that other theories are and that string theory is ordinary science in terms of describing nature and testing its explanations."
"Fortunately, an increasing active group of 'string phenomenologists' are focusing on formulating a string-based description of the world and testing that understanding."
"Some books and popular articles have claimed that because string theories are naturally formulated at such high energies or small distances, they cannot be tested. Obviously, collisions will never probe energy scales of 10^18 GeV, some 14 orders of magnitude larger than that of the LHC. But equally obviously, one does not have to be somewhere to test what's going
on there. Physicists have no doubt that a hot Big Bang occurred even though no one was there to witness it: We are convinced by the extensive evidence from relics such as the expanding universe, helium and other light-element abundances, and the cosmic microwave background radiation. You do not have to travel at the speed of light to test that it is the limiting speed."
"To make contact with the real world, a 10D or 11D string theory must be compactified. String theories with stable or metastable ground states usually also have supersymmetry, so the compactification process must break supersymmetry. ... Some compactifications have generated wrong predictions. ... It is simply wrong to say that string theory is not testable in basically the same way that F=ma or the Schoringer equation is testable. One specific test of a compactified string theory involves neutrino masses ..."
"Probably the ideal goal for those who want to examine string theory is to formulate testable properties that hold for all compactified string theories with metastable or stable vacua, regardless of the form of the compactification or other conditions such as supersymmetry breaking. Most knowledgeable physicists would agree that the gravitational force is one such property; its existence is a success for string theory."
"Earlier this year Bobby Acharya, Eric Kuflik, and I proposed a test that concerns the cosmological history of the universe, one that should be aplicable to any compactifies string theory. ..."
B. W. wrote:
Then again,the origin of the universe was never witnessed by human beings - conjecture is still conjecture...
"one does not have to be somewhere to test what's going on there. Physicists have no doubt that a hot Big Bang occurred even though no one was there to witness it: We are convinced by the extensive evidence from relics such as the expanding universe, helium and other light-element abundances, and the cosmic microwave background radiation. You do not have
to travel at the speed of light to test that it is the limiting speed."