s\u1eafc \u0111\u1ed9ng h\u1ecdc l\u01b0\u1ee3ng t\u1eed<\/em> (Quantum Chromodynamics, QCD). \u00d4ng \u0111\u00e3 t\u1eebng \u0111\u1ebfn sinh ho\u1ea1t v\u1edbi H\u1ed9i ngh\u1ecb khoa h\u1ecdc th\u1ebf gi\u1edbi t\u1ea1i Trung t\u00e2m ICISE Quy Nh\u01a1n c\u1ee7a GS Tr\u1ea7n Thanh V\u00e2n v\u00e0 L\u00ea Kim Ng\u1ecdc. NXX<\/p>\n\u2055\u2055\u2055<\/p>\n
A core aspect of our humanity is our desire to make sense of our place in the world, to understand what laws govern the universe \u2013 and if not to find the answer to why<\/i> we are here, then at least to find the answer to how<\/i> we are here. Physics is that part of science devoted to the investigation, at the most basic level, of the constituents of matter and the forces that govern their interactions. Down through the centuries, physics has successively delved deeper into microscopic realms, further back in time and farther out in space in pursuit of that quest. Our most powerful \u201cmicroscopes\u201d are particle accelerators, in which high-energy collisions of subatomic particles teach us about the structure of matter and interactions on the smallest scales. Our most powerful telescopes teach us about the largest structures in the cosmos, which had their origins in the big bang that began our universe. Remarkably, because the big bang was so hot and energetic, the same processes we now study in our particle accelerators were happening on a grand scale back then, and left their imprint on the distribution of galaxies we observe today with our telescopes. Over the last few decades, a remarkable synthesis has applied our understanding of fundamental particles and their interactions to calculate, with remarkable precision, how the universe began, how the matter in it came to be and how it coalesced to form galaxies such as our Milky Way, and so on down to stars such as our Sun.<\/p>\n
A remarkable theme emerging from that journey is the parallel development of physics and mathematics, the language we use to express the laws of nature. For instance, Newton developed the calculus in order to formulate his laws of gravity and the motion of bodies; and Einstein borrowed ideas from geometry in order to re-formulate gravitation in a framework consistent with his principle of relativity. In recent decades, string theory has emerged as the next step on this journey. It holds the promise of unifying the fundamental forces of nature, and at the same time has deepened the connection between mathematics and theoretical physics. In particular, it has enriched and deepened the connection between geometry and matter in new and unexpected ways.<\/p>\n
The route to the discovery and development of string theory has seen several surprising twists and turns, and we still have far to travel. It began as an attempt to make sense of the results being seen in particle accelerators in the 1950\u2019s and 60\u2019s. More powerful accelerators showed a proliferation of new strongly-interacting particles, which were shown qualitatively to fit the spectrum of a vibrating string whose tension would be set by the size and mass of the proton; the different vibrational modes were supposed to describe the different particles being observed. Eventually it was realized that such a string was merely a phenomenological approximation to the actual theory underlying strong nuclear forces, known as quantum chromodynamics (QCD)<\/i>. Attention of physicists turned to working out the details and predictions of QCD, as well as other aspects of particle interactions; string theory development dwindled to the work of just a few researchers by the mid-1970\u2019s. But in a remarkable reassessment, they made the bold proposal that rather than being a theory of just one of the fundamental forces, that string theory made more sense as a theory of all<\/i> the forces, including gravity. According to this proposal, the scale of the string tension was not the size of the proton, but rather the scale of quantum gravity \u2013 a size some twenty orders of magnitude smaller, and thought to be the smallest length scale in nature.<\/p>\n
It took another decade for this idea to ignite the interest of the broader community of theoretical physicists. By then, the \u201cStandard Model\u201d of particle physics, as it was now called, had been thoroughly explored, and proved wildly successful; and so physicists turned their attention to unifying it with Einstein\u2019s theory of gravity. This led to a proliferation of new results sometimes called the \u201cfirst superstring revolution\u201d<\/i>, showing how string theory could encompass the Standard Model, as well as resolve some major issues arising from attempts to merge Einstein\u2019s general relativity with quantum theory.<\/p>\n
The work of Stephen Hawking and others in the 1970\u2019s provided one of these puzzles. They showed that a black hole in quantum gravity must have an enormous number of possible internal states, while Einstein\u2019s general relativity gave no clue as to what these internal configurations might be. For two decades, the internal structure of black holes remained a mystery. Then in the mid-1990\u2019s, string theorists showed how to characterize the internal structure of a special class of black holes. Remarkably, their answer relied in an essential way on the structure of \u201cextra dimensions\u201d in string theory. It had been something of an embarrassment that the mathematical consistency of string theory requires there to be six or seven additional dimensions of space, beyond the three that are readily apparent in the world around us. In order to be compatible with observation, these extra dimensions must be extraordinarily small, perhaps as small as the quantum gravity scale; so small that they are unobserved. But these extra dimensions still have a structure. Supposing that the black hole is merely a large, heavy object built out of the fundamental constituents of string theory \u2013 strings, membranes, etc. \u2013 it was found that the number of ways that one could wrap those extended objects around the extra dimensions precisely accounts for the black hole\u2019s internal configurations. Tiny extra dimensions (and their intricate structure) turned out to be necessary ingredients to explain the internal states of these particular black holes.<\/p>\n
This landmark calculation was one of the great successes of the \u201csecond superstring revolution\u201d<\/i>, where we began to understand what happens when strings interact strongly with one another under the crushing forces inside a black hole. The implications of this result are still being worked out. Even though we can count the number of black hole states, we still don\u2019t understand exactly how string theory deals with the extraordinary forces at play at the spacetime singularity inside a black hole. That singularity bears some similarity with the big bang at the beginning of the universe, and so one may hope that understanding the structure of black holes may teach us about the early universe. In a related vein, observations have shown that the universe is mostly made up of matter and energy in forms quite different from those of everyday experience. A detailed accounting of the nature of this \u201cdark matter<\/i>\u201d and \u201cdark energy<\/i>\u201d has yet to be achieved, and remains a major challenge for string theory.<\/p>\n
Thus string theory represents a remarkable achievement of the human intellect, one discovered almost by accident. It builds upon decades of progress in understanding nature at the deepest level, and involves some of the most profound concepts in mathematics. At the same time it is still very much a work in progress. It has proven remarkably difficult to extract concrete experimental predictions from the theory, yet its achievements in encompassing both the Standard Model of particle physics and a quantum theory of gravity, and providing new insights into the structure of black holes, provide tantalizing evidence that we are on the right track.<\/p>\n
Chicago, 12\/9\/2018<\/p>\n
\nCh\u00fa gi\u1ea3i:<\/p>\n
1. Xem th\u00eam <\/span>T\u1ea1i sao l\u00fd thuy\u1ebft d\u00e2y?<\/span><\/i>, m\u1ee5c 5.2, hay trong Roger Penrose, <\/span>The Road to Reality. The complete guide to the laws of the universe<\/span><\/i>. Jonathan Cape, 2004, m\u1ee5c 31.5, trang 884 v\u00e0 ti\u1ebfp theo. Yoichiro Nambu, nh\u00e0 v\u1eadt l\u00fd M\u1ef9 g\u1ed1c Nh\u1eadt, gi\u1ea3i Nobel v\u1eadt l\u00fd n\u0103m 2008, c\u00f3 l\u1ebd l\u00e0 ng\u01b0\u1eddi \u0111\u1ea7u ti\u00ean v\u00e0o \u0111\u00e3 \u0111\u1ec1 xu\u1ea5t \u00fd t\u01b0\u1edfng d\u00e2y n\u0103m 1970 \u0111\u1ec3 gi\u1ea3i th\u00edch m\u1ed9t s\u1ed1 hi\u1ec7n t\u01b0\u1ee3ng quan s\u00e1t \u0111\u01b0\u1ee3c.<\/span><\/p>\n","protected":false},"excerpt":{"rendered":" A Brief History of String Theory by Emil Martinec Professor at the University of Chicago L\u1eddi n\u00f3i \u0111\u1ea7u. D\u01b0\u1edbi \u0111\u00e2y l\u00e0 nguy\u00ean b\u1ea3n ti\u1ebfng Anh b\u00e0i L\u01b0\u1ee3c s\u1eed l\u00fd thuy\u1ebft d\u00e2y c\u1ee7a Gi\u00e1o s\u01b0 v\u1eadt l\u00fd M\u1ef9 Emil Martinec \u1edf Vi\u1ec7n Enrico Fermi, \u0110\u1ea1i h\u1ecdc Chicago, v\u00e0 l\u00e0 gi\u00e1m \u0111\u1ed1c c\u1ee7a Trung t\u00e2m v\u1eadt<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_mi_skip_tracking":false,"jetpack_post_was_ever_published":false},"categories":[2],"tags":[],"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/rosetta.vn\/nguyenxuanxanh\/wp-json\/wp\/v2\/posts\/2235"}],"collection":[{"href":"https:\/\/rosetta.vn\/nguyenxuanxanh\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/rosetta.vn\/nguyenxuanxanh\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/rosetta.vn\/nguyenxuanxanh\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/rosetta.vn\/nguyenxuanxanh\/wp-json\/wp\/v2\/comments?post=2235"}],"version-history":[{"count":24,"href":"https:\/\/rosetta.vn\/nguyenxuanxanh\/wp-json\/wp\/v2\/posts\/2235\/revisions"}],"predecessor-version":[{"id":2264,"href":"https:\/\/rosetta.vn\/nguyenxuanxanh\/wp-json\/wp\/v2\/posts\/2235\/revisions\/2264"}],"wp:attachment":[{"href":"https:\/\/rosetta.vn\/nguyenxuanxanh\/wp-json\/wp\/v2\/media?parent=2235"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/rosetta.vn\/nguyenxuanxanh\/wp-json\/wp\/v2\/categories?post=2235"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/rosetta.vn\/nguyenxuanxanh\/wp-json\/wp\/v2\/tags?post=2235"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
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