tag:blogger.com,1999:blog-22973357.post1293488811315603957..comments2023-09-27T07:44:19.769-04:00Comments on Sabine Hossenfelder: Backreaction: What if... #5Sabine Hossenfelderhttp://www.blogger.com/profile/06151209308084588985noreply@blogger.comBlogger23125tag:blogger.com,1999:blog-22973357.post-30364971327138927242008-12-14T17:07:00.000-05:002008-12-14T17:07:00.000-05:00If A is an observable, then so isA(t)= exp(i H t/h...If A is an observable, then so is<BR/><BR/>A(t)= exp(i H t/hbar)A exp(-i H t/hbar) <BR/><BR/>So, quantum mechanics does allow you to measure now who will be the president of the US in the year 2013. :)Count Iblishttps://www.blogger.com/profile/07429017672028256731noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-39626112165794787132008-12-08T11:59:00.000-05:002008-12-08T11:59:00.000-05:00And if you were to understand what Peter Shor just...And if you were to understand what Peter Shor just said, some might even use it now like Susskind did to ponder in a thought experiment the relevance of the horizon and "a elephant" to wonder about the inside of a blackhole:)<BR/><BR/>Best, :)PlatoHagelhttps://www.blogger.com/profile/00849253658526056393noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-20790033730552934002008-12-08T11:02:00.000-05:002008-12-08T11:02:00.000-05:00Can I muddy the waters further by pointing out tha...Can I muddy the waters further by pointing out that we <I>already</I> have a way to predict the results of a quantum measurement. Suppose I hold one of a pair of entangled photons in the EPR state, and you hold the other. Theoretically (assuming ideal experimental equipment) I can predict the results of any measurement you make on your photon. This experiment has indeed been done, and I think theAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-22973357.post-49776955339136953292008-12-08T09:59:00.000-05:002008-12-08T09:59:00.000-05:00I meant non-probabilisticallyI meant non-probabilisticallySabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-37363583087977716132008-12-08T09:58:00.000-05:002008-12-08T09:58:00.000-05:00I thought the probability density was already a wa...I thought the probability density was already a way for us to predict the outcome of a measurement. Was something else meant based off of the question that i simply don't see?Shawn Wilkinsonhttps://www.blogger.com/profile/18308205724057373941noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-51053888999807357842008-12-06T06:27:00.000-05:002008-12-06T06:27:00.000-05:00Hi Bee,“Either way, my thoughts were that such a c...Hi Bee,<BR/><BR/>“Either way, my thoughts were that such a conclusion would be faced with major sociological resistance up to the point of denial, since it would mean we have no free will.”<BR/><BR/>All good points including this last one. The way I look at it something can be unknowable while still being determinant. This means simply that although cause still leads to effect, being able to Phil Warnellhttps://www.blogger.com/profile/15671311338712852659noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-88872966248550717832008-12-05T21:47:00.000-05:002008-12-05T21:47:00.000-05:00Maybe a horoscope operates like a QM wave function...Maybe a horoscope operates like a QM wave function? It tells you what is possible, but doesn't guarantee a particular outcome.Arunhttps://www.blogger.com/profile/03451666670728177970noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-59358066576112927862008-12-05T19:22:00.000-05:002008-12-05T19:22:00.000-05:00Hi Phil,I would think that if we could predict the...Hi Phil,<BR/><BR/>I would think that if we could predict the future, we can not change it. The one is incompatible with the other. It's the same thing that puzzles me about horoscopes. Why do people read them? They either say what is going to happen and you can't change it, then what's the point of knowing it anyway. Or you can change it, then it's not a useful prediction. <BR/><BR/>Anyway, the Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-47470161845559726922008-12-05T19:15:00.000-05:002008-12-05T19:15:00.000-05:00Hi Andy,Well, that is an interesting point which t...Hi Andy,<BR/><BR/>Well, that is an interesting point which touches on a much more difficult question, that is how to combine the collapse of the wave-function with gravity. Suppose the moon was not 'there' if you wouldn't look at it (measure it). What would happen to it's gravitational field? Best,<BR/><BR/>B.Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-74414307589150139112008-12-05T19:14:00.000-05:002008-12-05T19:14:00.000-05:00This would have to be a way to predict the outcome...This would have to be a way to predict the outcome of a "general" quantum measurement, since we can already predict the outcome of idealized same-basis measurements already. For example, if I produce a horizontal polarized photon I can predict it will near definitely pass a horizontal filter. But that's only from knowing how the photon was produced in the first place, and I wouldn't know what Neil Bateshttps://www.blogger.com/profile/04564859009749481136noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-71798398222305345372008-12-05T19:13:00.000-05:002008-12-05T19:13:00.000-05:00Hi Peter,You hit the nail on the head. Evidently, ...Hi Peter,<BR/><BR/>You hit the nail on the head. Evidently, it follows from what you say that if you'd want to avoid major problems with causality, you can't change your mind without spoiling the predictions. Or, to put it differently, the settings of the measurement are part of the input necessary to make the predictions. Best,<BR/><BR/>B.Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-40871081690129554802008-12-05T16:54:00.000-05:002008-12-05T16:54:00.000-05:00We'd know if the moon was there without actually l...We'd know if the moon was there without actually looking at it, which always bugs me cuz then I have to crane my neck at an awkward angle.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-22973357.post-3932868111517171072008-12-05T14:21:00.000-05:002008-12-05T14:21:00.000-05:00Blood Music, Greg Bear.The only thing saving manki...<I>Blood Music</I>, Greg Bear.<BR/><BR/>The only thing saving mankind is its inability to predict the future. Science fiction exists to enumerate and discard bad futures.<BR/><BR/>Be careful what you do not wish for, too.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-22973357.post-21578888753901460552008-12-05T11:53:00.000-05:002008-12-05T11:53:00.000-05:00Suppose you predicted the outcome in one basis, an...Suppose you predicted the outcome in one basis, and then changed your mind and measured in a different basis. You'd be able to effectively measure in two non-commuting bases simultaneously. It's well know that this lets you communicate faster than the speed of light, which is equivalent to being able to send messages backwards in time. So, the consequences would be that physicists would get very Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-22973357.post-55802702211160875502008-12-05T08:59:00.000-05:002008-12-05T08:59:00.000-05:00I can't explain why, but I think time would stop s...I can't explain why, but I think time would stop somehow.Rae Annhttps://www.blogger.com/profile/10239791074376508016noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-50435346173932178872008-12-05T08:20:00.000-05:002008-12-05T08:20:00.000-05:00It would be a sad day for the scientific community...It would be a sad day for the scientific community ...Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-22973357.post-52877185076557938622008-12-05T08:03:00.000-05:002008-12-05T08:03:00.000-05:00FTL communication, breakdown of relativity and, ev...FTL communication, breakdown of relativity and, eventually, instantaneous space explorationAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-22973357.post-68870805942462711452008-12-05T08:02:00.000-05:002008-12-05T08:02:00.000-05:00Then we 'll call these measurements classical.Then we 'll call these measurements classical.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-22973357.post-75751735394911317532008-12-05T08:01:00.000-05:002008-12-05T08:01:00.000-05:00I would try to be a Jedi.I would try to be a Jedi.Daniel de França MTd2https://www.blogger.com/profile/01281817409696805377noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-72557986360675150002008-12-05T07:47:00.000-05:002008-12-05T07:47:00.000-05:00I would just like to further point out that with t...I would just like to further point out that with the current political events taking place in my nation (Canada) indicating that there is little likely hood that consciousness is of a collective nature and thereby suggests perhaps reality truly may indeed be both multiple and private:-)Phil Warnellhttps://www.blogger.com/profile/15671311338712852659noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-67613970736211159762008-12-05T07:28:00.000-05:002008-12-05T07:28:00.000-05:00Oh yes I forgot to add if consciousness did lend s...Oh yes I forgot to add if consciousness did lend some power to alter reality and as there are more then one which can; does this infer there are many private realities or the resultant sum total of a collective one?Phil Warnellhttps://www.blogger.com/profile/15671311338712852659noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-36481957391311468642008-12-05T07:19:00.000-05:002008-12-05T07:19:00.000-05:00we should all throw a party on Einstein's behalfwe should all throw a party on Einstein's behalfAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-22973357.post-75471670270125174002008-12-05T07:10:00.000-05:002008-12-05T07:10:00.000-05:00I would say it would allow us to predict the futur...I would say it would allow us to predict the future. The question then would be if we would be able to change it or would such a change produce yet another version of reality? The former is called destiny the latter many worlds or perhaps free will if you prefer to have consciousness have some reality as to have worth.Phil Warnellhttps://www.blogger.com/profile/15671311338712852659noreply@blogger.com