People all have their own ideas of what a time machine would look like. If you are a fan of the 1960 movie version of H. G. Wells\u2019s classic novel, it would be a steampunk sled with a red velvet chair, flashing lights, and a giant spinning wheel on the back. For those whose notions of time travel were formed in the 1980s, it would be a souped-up stainless steel sports car. Details of operation vary from model to model, but they all have one thing in common: When someone actually travels through time, the machine ostentatiously dematerializes, only to reappear many years in the past or future. And most people could tell you that such a time machine would never work, even if it looked like a DeLorean.<\/p>\n
They would be half right: That is not how time travel might work, but time travel in some other form is not necessarily off the table. Since time is kind of like space (the four dimensions go hand in hand), a working time machine would zoom off like a rocket rather than disappearing in a puff of smoke. Einstein described our universe in four dimensions: the three dimensions of space and one of time. So traveling back in time is nothing more or less than the fourth-dimensional version of walking in a circle. All you would have to do is use an extremely strong gravitational field, like that of a black hole, to bend space-time. From this point of view, time travel seems quite difficult but not obviously impossible.<\/p>\n
These days, most people feel comfortable with the notion of curved space-time. What they trip up on is actually a more difficult conceptual problem, the time travel paradox. This is the worry that someone could go back in time and change the course of history. What would happen if you traveled into the past, to a time before you were born, and murdered your parents? Put more broadly, how do we avoid changing the past as we think we have already experienced it? At the moment, scientists don\u2019t know enough about the laws of physics to say whether these laws would permit the time equivalent of walking in a circle\u2014or, in the parlance of time travelers, a \u201cclosed timelike curve.\u201d If they don\u2019t permit it, there is obviously no need to worry about paradoxes. If physics is not an obstacle, however, the problem could still be constrained by logic. Do closed timelike curves necessarily lead to paradoxes?<\/p>\n
<\/p>\n","protected":false},"excerpt":{"rendered":"
People all have their own ideas of what a time machine would look like. If you are a fan of the 1960 movie version of H. G. Wells\u2019s classic novel, it would be a steampunk sled with a red velvet chair, flashing lights, and a giant spinning wheel on the back. For those whose notions […]<\/p>\n","protected":false},"author":641,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[],"class_list":["post-266920","post","type-post","status-publish","format-standard","hentry","category-news"],"_links":{"self":[{"href":"https:\/\/mereja.media\/index\/wp-json\/wp\/v2\/posts\/266920","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/mereja.media\/index\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/mereja.media\/index\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/mereja.media\/index\/wp-json\/wp\/v2\/users\/641"}],"replies":[{"embeddable":true,"href":"https:\/\/mereja.media\/index\/wp-json\/wp\/v2\/comments?post=266920"}],"version-history":[{"count":0,"href":"https:\/\/mereja.media\/index\/wp-json\/wp\/v2\/posts\/266920\/revisions"}],"wp:attachment":[{"href":"https:\/\/mereja.media\/index\/wp-json\/wp\/v2\/media?parent=266920"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/mereja.media\/index\/wp-json\/wp\/v2\/categories?post=266920"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/mereja.media\/index\/wp-json\/wp\/v2\/tags?post=266920"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}