M-Theory, String Theory and Supersymmetry

you have probably heard of string theory an attractive development in theoretical physics which has run wild through the scientific community and media alike it has seen so much attention due to its incredible answers to deep questions of fundamental physics to the extent that some consider it a candidate for a theory of everything string theory itself is not exactly a theory but more a type of theory called a theoretical framework through which there are multiple different versions of the same based principle string theories based principle is that all the points of particle physics like leptons or quarks are replaced by one-dimensional strings which are on the scale of the Planck length and are either open or closed these strings vibrate and the way they vibrate determines which particle they look like at a larger scale but for the maths to support various string theories we need more dimensions at the moment we are very happy with our three spatial and one time dimension but string theorists imagined that there could be many more those on extreme theory for instance theorizes that there are 27 yes 27 different dimensions to our universe the reason that we don't notice these extra dimensions is because they're curled up incredibly small imagine you have a pole on which tiny object can move close up you can easily see how the object can move not only up and down the pole but around the circumference as well and the object itself would only be able to comprehend these two dimensions however if you step back far enough you will only be able to notice one dimension of movement up and down this is the essence of extra dimensional space or hyperspace string Theory's allow quantum gravity to be explained something that very few quantum theories have been able to do gravity as understood by Einstein's general theory of relativity often as serious disagreements with quantum physics one main reason for this is the gravity describing the geometry of space-time itself requires precise measurements of distance and at the quantum level these properties cannot be measured precisely enough due to the Heisenberg uncertainty principle the brilliance of string theory is that it introduces gravitons particles that mediate gravity allowing gravitational interactions to be explained in quantum physics this was what caused some to name string theory a potential theory of everything despite others criticizing it for its unfalsifiable T well what makes a theory a theory of everything a theory of everything in the most basic sense is a theory that encompasses well everything of modern physics there seems like a great deal of work but thankfully a lot of it has already been done we in fact have a single model humbly called the standard model that describes almost all of the known universe excluding one or two final stepping stones the biggest of these final pieces is gravity and a clear signpost that you have a theory of everything on your hands is if it connects gravity to the standard model as we know general relativity Einstein's theory of gravity really dislikes quantum theories but there is another very promising scientific principle called supersymmetry that could help us combine gravity and quantum physics supersymmetry is the principle of treating forces and matter equally and predicts cousin particles for every elementary particle we've observed called superpartners these superpartners are of the opposite lost their regular versions for instance electrons supersymmetric partners of the electron are bosons where electrons are fermions a supersymmetric theory would have its force equations identical to matter equations and for this reason many physicists are attracted to the way supersymmetry relates force to matter bosons to fermions making the standard model more elegant physicists already appreciate the symmetry in particle physics between the six quarks and antiquarks and between the six leptons and anti leptons and can see the mathematical significance of this symmetry on the other hand many criticize supersymmetry on the grounds that no superpartner particles have been observed and to test the principle it would take a gargantuan sized particle accelerator capable of collisions up to seven million times more energetic than the LHC's nonetheless supersymmetry when combined with general relativity results in very elegant and satisfactory solutions and this is called super gravity supersymmetry can also be applied to string theory and this gave rise to 5 super string theories each with 10 total dimensions these super string theories individually explain a number of questions in quantum physics and do so extremely well however these super string theories were found to be perturbative with no single ones seeming to be a theory of everything and it looked like string theory had failed to reveal the nature of our universe there was until an American physicist named Edward Witten noticed that the five string theories could be mapped to one another by certain conditions known as dualities then the string theory conference at the University of Southern California in 1995 he suggested that instead of these string theories being distinct theories they can in fact be cornerstones of a more fundamental theory called m-theory this started a huge amount of work which became known as the second superstring revolution and theory could be defined as a proposal for a unified quantum theory of the fundamental constituents and forces of nature which contains within it the five super string theories and super gravity it has since been considered the best candidate we have for a theory of everything by the likes of Stephen Hawking and Michiyo Kaku but the M&M theory might as well stand for mystery or miracle because no one really knows very much about M theory at all even its name M theory to be a single theory or a network of different theories in either case we are already aware of some of its base principles firstly M theory is 11 dimensional and it contains not just one-dimensional strings but other fundamental objects with a range of different dimensions called P brains where P runs from 0 to 9 this includes zero dimensional points membranes which are two-dimensional sheets three-dimensional blobs four dimensional hyper blobs and so forth up to nine brains which are pretty difficult to imagine the 11 dimensions of M theory can't in our Familia three macro dimensions and time dimension but what about the remaining seven tiny dimensions these extra dimensions must be either culled up or dry tangled somehow otherwise they would cease to be tiny dimensions and the maths of m-theory restricts the number of ways the internal space can be shaped as such we know that the shape of a tunnel space directly affects the values of physical constants such as the charge of the proton and the way elementary particles interact in this way the shape of internal space determines the laws of nature less fundamental than those of m-theory like the laws of chemistry we can say therefore that whilst our universe is a certain way of shaping hyperspace and so certain laws of nature the laws of m-theory allow fer of the universes with different ways of shaping hyperspace and so vastly different laws of nature how different ten to the five hundred different according to M faeries mathematics this means that M theory allows for ten to the five hundred different universes and ten to the five hundred is a very large number this multiverse possibility is just another way empathy escorting the attention of so many but is M theory the grand unified theory we have been looking for for that we will have to wait and see but should it be confirmed by observational evidence we will have made huge progress in understanding our universe

Channel: Charlie Aram

Views: 136,943

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Id: Bpek8j3QnAs

Length: 8min 14sec (494 seconds)

Published: Tue Jun 09 2020