<story><title>A delightful quirk of relativity theory</title><url>https://twitter.com/MarkusDeserno/status/1482811504424542211</url></story><parent_chain><item><author>awb</author><text>A few issues with the “free will” debate.&lt;p&gt;1) Define “free”&lt;p&gt;2) How do you test your hypothesis?&lt;p&gt;You’re trying to apply logic to an untestable philosophical debate. If you believe free will doesn’t exist, you can’t design an experiment that would invalidate that belief. And if your theory is untestable and unfalsifiable, then what good is it other than a creative exercise?&lt;p&gt;However, we do know from Quantum Mechanics that the universe is probabilistic and not deterministic:&lt;p&gt;&lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;www.thegreatcoursesdaily.com&amp;#x2F;quantum-universe-fundamentally-probabilistic-not-deterministic&amp;#x2F;#:~:text=The%20quantum%20universe%20is%20fundamentally,laws%20must%20be%20strictly%20deterministic.&amp;amp;text=It%20was%20this%20kind%20of,new%20theory%20of%20quantum%20mechanics&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;www.thegreatcoursesdaily.com&amp;#x2F;quantum-universe-fundam...&lt;/a&gt;.&lt;p&gt;So, we do know that the universe is not pre-determined and cannot be calculated in advance, but if you want to believe in humans as fully deterministic (or some other definition of no free will) inside of a non-deterministic environment, I haven’t heard anyone propose an experiment that could test that, at which point the debate of “free will” is relegated to the realm of thought experiments rather than science.&lt;p&gt;So, perhaps the better question is: Does it serve you better to believe there is free will or no free will? And leave it at that.</text></item><item><author>danbruc</author><text>&lt;i&gt;Rescuing free-will from the jaws of spacetime would be cool!&lt;/i&gt;&lt;p&gt;Free will does not exist. It is logically inconsistent. Either your choice is some function of your current state and the environment you are in, then the choice is not free, or it is independent of your current state and the environment you are in, then it is not your choice in any meaningful way, it is just the result of a coin flip.&lt;p&gt;You can do some mental gymnastics, define free will as being able to do what you want, define it as being free of various kinds of constraints, call it free if the choice is not computable in advance, if you can not measure all necessary variables, in practice or in theory, ... If you are happy with any of those definitions, fine, then you might have this kind of free will, but I would not consider any of those particularly interesting.</text></item><item><author>irthomasthomas</author><text>This would be more fun in a blog post. Twitter is a fucking horrible format for a complex analysis of special relativity.&lt;p&gt;That aside, my favourite quirk from relativity is this:&lt;p&gt;&lt;pre&gt;&lt;code&gt;  &amp;quot;The more you move in space, the less you move in time.&amp;quot;
&lt;/code&gt;&lt;/pre&gt;
Like relativity in general, it sounds simple enough, but it&amp;#x27;s consequences are profoundly shocking. (That is, if you take the time to understand it, and don&amp;#x27;t leap to the conclusion that you know relativity better than Einstein or Penrose ;)&lt;p&gt;Take the case of two people on Earth, one stationary and one travelling past in a car. They each have a different reference frame, and a different set events which make up their present. Now imagine that there is an alien government in Andromeda debating a possible invasion of Earth. In the reference frame of the person on Earth who is moving, the debate is still going on. But, in the reference frame of the stationary person, it is a day or so later in Andromeda, and the invasion fleet is already on it&amp;#x27;s way! In nature there is no absolute reference frame we can call base reality, and both observers reference frames are equally valid. Then the outcome of the invasion debate is a foregone conclusion. How can there be any room for free will in the deliberations of the alien government? This is the crux of the Andromeda Paradox and the Reitdijk-Putnam-Penrose argument.&lt;p&gt;BTW:&lt;p&gt;&lt;pre&gt;&lt;code&gt;  &amp;quot;Notice that neither observer can actually &amp;quot;see&amp;quot; what is happening in Andromeda, because light from Andromeda (and the hypothetical alien fleet) will take 2.5 million years to reach Earth. The argument is not about what can be &amp;quot;seen&amp;quot;; it is purely about what events different observers consider to occur in the present moment.&amp;quot;
&lt;/code&gt;&lt;/pre&gt;
&lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;en.wikipedia.org&amp;#x2F;wiki&amp;#x2F;Rietdijk%E2%80%93Putnam_argument&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;en.wikipedia.org&amp;#x2F;wiki&amp;#x2F;Rietdijk%E2%80%93Putnam_argume...&lt;/a&gt;&lt;p&gt;More info
&lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;en.m.wikipedia.org&amp;#x2F;wiki&amp;#x2F;Relativity_of_simultaneity&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;en.m.wikipedia.org&amp;#x2F;wiki&amp;#x2F;Relativity_of_simultaneity&lt;/a&gt;&lt;p&gt;Edit: If you know of any serious alternatives to the 4D spacetime&amp;#x2F; block universe theory then I would love to read it. Rescuing free-will from the jaws of spacetime would be cool!</text></item></parent_chain><comment><author>vidarh</author><text>&amp;gt; You’re trying to apply logic to an untestable philosophical debate. If you believe free will doesn’t exist, you can’t design an experiment that would invalidate that belief. And if your theory is untestable and unfalsifiable, then what good is it other than a creative exercise?&lt;p&gt;This is reversing the burden of proof. The issue with &amp;quot;free will&amp;quot; is getting those who think there is a meaningful &amp;quot;free will&amp;quot; concept to actually define what they mean.&lt;p&gt;Look through this discussion and see the comments trying to justify the existence of free will, and look for definitions of what they actually mean by that.&lt;p&gt;&amp;gt; However, we do know from Quantum Mechanics that the universe is probabilistic and not deterministic:&lt;p&gt;That&amp;#x27;s a meaningless distinction in this context. The point is that nobody has presented a mechanism whereby you can inject any form of agency that fits a definition of &amp;quot;free&amp;quot; (see your own point: define &amp;quot;free&amp;quot;) that doesn&amp;#x27;t devolve to smoke and mirrors that way.&lt;p&gt;In order to do so, there&amp;#x27;d need to be something that would lead to measurable biases in outcomes that can not be explained by the probabilities.&lt;p&gt;The rest of your argument devolves to Russel&amp;#x27;s teapot: As long as nobody has posited a reasonable definition that&amp;#x27;d give rise to a theory of what free will might mean, the notion is so absurd that it is entirely reasonable to say that free will makes no sense.&lt;p&gt;If you can present a definition that can&amp;#x27;t easily be shown to be just smoke and mirrors and which somehow makes sense to people, even without coming up with ways of actually testing it, I might be tempted to moderate that claim, but I&amp;#x27;ve had these discussions with people for decades, and in none of them have anyone ever managed to come up with a cohesive definition of what free will would even mean that doesn&amp;#x27;t very easily start looking distinctly &amp;quot;unfree&amp;quot;.&lt;p&gt;There are clearly definitions of free will that would allow something you label with that term to exist. But I challenge you to come up with one that people would agree is both &amp;quot;free&amp;quot; and &amp;quot;will&amp;quot;.</text></comment>
<story><title>A delightful quirk of relativity theory</title><url>https://twitter.com/MarkusDeserno/status/1482811504424542211</url></story><parent_chain><item><author>awb</author><text>A few issues with the “free will” debate.&lt;p&gt;1) Define “free”&lt;p&gt;2) How do you test your hypothesis?&lt;p&gt;You’re trying to apply logic to an untestable philosophical debate. If you believe free will doesn’t exist, you can’t design an experiment that would invalidate that belief. And if your theory is untestable and unfalsifiable, then what good is it other than a creative exercise?&lt;p&gt;However, we do know from Quantum Mechanics that the universe is probabilistic and not deterministic:&lt;p&gt;&lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;www.thegreatcoursesdaily.com&amp;#x2F;quantum-universe-fundamentally-probabilistic-not-deterministic&amp;#x2F;#:~:text=The%20quantum%20universe%20is%20fundamentally,laws%20must%20be%20strictly%20deterministic.&amp;amp;text=It%20was%20this%20kind%20of,new%20theory%20of%20quantum%20mechanics&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;www.thegreatcoursesdaily.com&amp;#x2F;quantum-universe-fundam...&lt;/a&gt;.&lt;p&gt;So, we do know that the universe is not pre-determined and cannot be calculated in advance, but if you want to believe in humans as fully deterministic (or some other definition of no free will) inside of a non-deterministic environment, I haven’t heard anyone propose an experiment that could test that, at which point the debate of “free will” is relegated to the realm of thought experiments rather than science.&lt;p&gt;So, perhaps the better question is: Does it serve you better to believe there is free will or no free will? And leave it at that.</text></item><item><author>danbruc</author><text>&lt;i&gt;Rescuing free-will from the jaws of spacetime would be cool!&lt;/i&gt;&lt;p&gt;Free will does not exist. It is logically inconsistent. Either your choice is some function of your current state and the environment you are in, then the choice is not free, or it is independent of your current state and the environment you are in, then it is not your choice in any meaningful way, it is just the result of a coin flip.&lt;p&gt;You can do some mental gymnastics, define free will as being able to do what you want, define it as being free of various kinds of constraints, call it free if the choice is not computable in advance, if you can not measure all necessary variables, in practice or in theory, ... If you are happy with any of those definitions, fine, then you might have this kind of free will, but I would not consider any of those particularly interesting.</text></item><item><author>irthomasthomas</author><text>This would be more fun in a blog post. Twitter is a fucking horrible format for a complex analysis of special relativity.&lt;p&gt;That aside, my favourite quirk from relativity is this:&lt;p&gt;&lt;pre&gt;&lt;code&gt;  &amp;quot;The more you move in space, the less you move in time.&amp;quot;
&lt;/code&gt;&lt;/pre&gt;
Like relativity in general, it sounds simple enough, but it&amp;#x27;s consequences are profoundly shocking. (That is, if you take the time to understand it, and don&amp;#x27;t leap to the conclusion that you know relativity better than Einstein or Penrose ;)&lt;p&gt;Take the case of two people on Earth, one stationary and one travelling past in a car. They each have a different reference frame, and a different set events which make up their present. Now imagine that there is an alien government in Andromeda debating a possible invasion of Earth. In the reference frame of the person on Earth who is moving, the debate is still going on. But, in the reference frame of the stationary person, it is a day or so later in Andromeda, and the invasion fleet is already on it&amp;#x27;s way! In nature there is no absolute reference frame we can call base reality, and both observers reference frames are equally valid. Then the outcome of the invasion debate is a foregone conclusion. How can there be any room for free will in the deliberations of the alien government? This is the crux of the Andromeda Paradox and the Reitdijk-Putnam-Penrose argument.&lt;p&gt;BTW:&lt;p&gt;&lt;pre&gt;&lt;code&gt;  &amp;quot;Notice that neither observer can actually &amp;quot;see&amp;quot; what is happening in Andromeda, because light from Andromeda (and the hypothetical alien fleet) will take 2.5 million years to reach Earth. The argument is not about what can be &amp;quot;seen&amp;quot;; it is purely about what events different observers consider to occur in the present moment.&amp;quot;
&lt;/code&gt;&lt;/pre&gt;
&lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;en.wikipedia.org&amp;#x2F;wiki&amp;#x2F;Rietdijk%E2%80%93Putnam_argument&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;en.wikipedia.org&amp;#x2F;wiki&amp;#x2F;Rietdijk%E2%80%93Putnam_argume...&lt;/a&gt;&lt;p&gt;More info
&lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;en.m.wikipedia.org&amp;#x2F;wiki&amp;#x2F;Relativity_of_simultaneity&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;en.m.wikipedia.org&amp;#x2F;wiki&amp;#x2F;Relativity_of_simultaneity&lt;/a&gt;&lt;p&gt;Edit: If you know of any serious alternatives to the 4D spacetime&amp;#x2F; block universe theory then I would love to read it. Rescuing free-will from the jaws of spacetime would be cool!</text></item></parent_chain><comment><author>danbruc</author><text>&lt;i&gt;However, we do know from Quantum Mechanics that the universe is probabilistic and not deterministic&lt;/i&gt;&lt;p&gt;That is not true, quantum mechanics - more specifically the Schrödinger equation - is deterministic. What is not deterministic is the wave function collapse but that is also incompatible with the Schrödinger equation because it implies non-unitary evolution of the wave function. And we have - as far as I know - no really good ideas how to resolve this. In consequence I think it would be premature to declare that the universe is definitively non-deterministic.</text></comment>