<story><title>Big Bounce Simulations Challenge the Big Bang</title><url>https://www.quantamagazine.org/big-bounce-simulations-challenge-the-big-bang-20200804/</url></story><parent_chain><item><author>simonh</author><text>Well, there&amp;#x27;s the Marvin Minsky answer. He believed that there is no difference between a possible universe and a real universe. Think of the difference between an algorithm that only exists in theory and running the algorithm on a computer. What do we add to the result by running it? We don&amp;#x27;t change the result, or grant it any greater validity in a metaphysical sense. The answer was always going to be the same and always will be the same. Minsky thought that our world is simply a possible world, but to suppose it is &amp;#x27;real&amp;#x27; or not doesn&amp;#x27;t change anything and more than doing a calculation makes the result correct. It simply is.&lt;p&gt;It&amp;#x27;s similar in some ways to the concept of block time, in which there is no progression of time. The universe simply exists and the perception of the &amp;#x27;present&amp;#x27; is an illusion. Similarly for Minsky the perception of reality or existence is an illusion.</text></item><item><author>mytailorisrich</author><text>The metaphysical issues are unavoidable because whatever the theory we come up with or, I think, whatever the reality is, it can only fall within 2 possibilities:&lt;p&gt;- Infinity: There is no beginning and something always precedes the &amp;#x27;current&amp;#x27; step (e.g. the Big Bang occurred out of something)&lt;p&gt;- Discontinuity: There is a beginning. Everything suddenly started out of nothing.&lt;p&gt;While both options are hard to grasp for the human mind, the second one, which is the standard Big Bang also sits very uncomfortably with Physics&amp;#x27; concepts and is the more &amp;#x27;disturbing&amp;#x27; of the two. I think that&amp;#x27;s why people have been looking for alternatives to the standard Big Bang theory.&lt;p&gt;Infinity, is still unfathomable but at least it is easier to fit Maths and Physics around.&lt;p&gt;Even adding God to the mix still leads to these 2 options, because if the Universe was created by &amp;#x27;God&amp;#x27; it implies that the Big Bang is not the beginning and that something (God) pre-existed. The idea that we might be in a simulation is equivalent to a creator God, just more hi-tech.&lt;p&gt;It really seems to me that these alternatives, infinity or discontinuity, are inescapable.</text></item><item><author>Zamicol</author><text>I despise the big bounce because it&amp;#x27;s dogmatic in origin.  &amp;quot;It makes sense that the universe just bounces instead of &amp;#x27;coming from nowhere&amp;#x27;!&amp;quot;&lt;p&gt;Every time cosmologists looked, the universe got bigger and suggested growth.  The big bounce at no point in history ever looked right.  Moreover, the big bounce kicks the bucket down the road.  It ultimately has the same metaphysical issues.&lt;p&gt;I find the reasoning poor as well.  &amp;quot;I don&amp;#x27;t like inflation&amp;quot; != &amp;quot;The universe ends in contraction&amp;quot;.  Yes, it&amp;#x27;s proven difficult to explain CMB smoothness, but this doesn&amp;#x27;t mean the big bounce is a better candidate than other non-empirical ideas.&lt;p&gt;I&amp;#x27;m confident truth will be far stranger than big bounce fiction.</text></item></parent_chain><comment><author>ardy42</author><text>&amp;gt; It&amp;#x27;s similar in some ways to the concept of block time, in which there is no progression of time. The universe simply exists and the perception of the &amp;#x27;present&amp;#x27; is an illusion. Similarly for Minsky the perception of reality or existence is an illusion.&lt;p&gt;Labeling something an &amp;quot;illusion&amp;quot; like that seems like a massive cop-out, made by a mapmaker to avoid confronting the fact that their maps don&amp;#x27;t fully represent the territory.  Fossils weren&amp;#x27;t illusions, and I don&amp;#x27;t think the present or existence are illusions either.</text></comment>
<story><title>Big Bounce Simulations Challenge the Big Bang</title><url>https://www.quantamagazine.org/big-bounce-simulations-challenge-the-big-bang-20200804/</url></story><parent_chain><item><author>simonh</author><text>Well, there&amp;#x27;s the Marvin Minsky answer. He believed that there is no difference between a possible universe and a real universe. Think of the difference between an algorithm that only exists in theory and running the algorithm on a computer. What do we add to the result by running it? We don&amp;#x27;t change the result, or grant it any greater validity in a metaphysical sense. The answer was always going to be the same and always will be the same. Minsky thought that our world is simply a possible world, but to suppose it is &amp;#x27;real&amp;#x27; or not doesn&amp;#x27;t change anything and more than doing a calculation makes the result correct. It simply is.&lt;p&gt;It&amp;#x27;s similar in some ways to the concept of block time, in which there is no progression of time. The universe simply exists and the perception of the &amp;#x27;present&amp;#x27; is an illusion. Similarly for Minsky the perception of reality or existence is an illusion.</text></item><item><author>mytailorisrich</author><text>The metaphysical issues are unavoidable because whatever the theory we come up with or, I think, whatever the reality is, it can only fall within 2 possibilities:&lt;p&gt;- Infinity: There is no beginning and something always precedes the &amp;#x27;current&amp;#x27; step (e.g. the Big Bang occurred out of something)&lt;p&gt;- Discontinuity: There is a beginning. Everything suddenly started out of nothing.&lt;p&gt;While both options are hard to grasp for the human mind, the second one, which is the standard Big Bang also sits very uncomfortably with Physics&amp;#x27; concepts and is the more &amp;#x27;disturbing&amp;#x27; of the two. I think that&amp;#x27;s why people have been looking for alternatives to the standard Big Bang theory.&lt;p&gt;Infinity, is still unfathomable but at least it is easier to fit Maths and Physics around.&lt;p&gt;Even adding God to the mix still leads to these 2 options, because if the Universe was created by &amp;#x27;God&amp;#x27; it implies that the Big Bang is not the beginning and that something (God) pre-existed. The idea that we might be in a simulation is equivalent to a creator God, just more hi-tech.&lt;p&gt;It really seems to me that these alternatives, infinity or discontinuity, are inescapable.</text></item><item><author>Zamicol</author><text>I despise the big bounce because it&amp;#x27;s dogmatic in origin.  &amp;quot;It makes sense that the universe just bounces instead of &amp;#x27;coming from nowhere&amp;#x27;!&amp;quot;&lt;p&gt;Every time cosmologists looked, the universe got bigger and suggested growth.  The big bounce at no point in history ever looked right.  Moreover, the big bounce kicks the bucket down the road.  It ultimately has the same metaphysical issues.&lt;p&gt;I find the reasoning poor as well.  &amp;quot;I don&amp;#x27;t like inflation&amp;quot; != &amp;quot;The universe ends in contraction&amp;quot;.  Yes, it&amp;#x27;s proven difficult to explain CMB smoothness, but this doesn&amp;#x27;t mean the big bounce is a better candidate than other non-empirical ideas.&lt;p&gt;I&amp;#x27;m confident truth will be far stranger than big bounce fiction.</text></item></parent_chain><comment><author>hacknat</author><text>It’s a pleasing cognitive answer, but doesn’t really fit well with math or physics. Time is an emergent property of the Universe that we can measure and compare with a more platonic mathematical model of time. Also, you could make the argument that Minsky’s argument is just a form of discontinuity.</text></comment>