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  • 23-05-2019 12:08pm
    #1
    WrathOfNothing
    Registered Users Posts: 6 ✭


    Been reading a bit and was wondering if you're not going with God and all that, where did it all come from? How can something come from nothing? Not saying this as an argument for God, just a bit confused. What are the other explanations? How will it all end up?


Comments

  • #2
    robindch
    Moderators, Society & Culture Moderators Posts: 24,420 Mod ✭✭✭✭robindch


    The most plausible of the current theories concerning the early universe suggest that time itself "began" at the Big Bang, so the concept of "what happened before" doesn't really apply.

    Also, externalizing the creation of the universe to a deity doesn't achieve anything anyway, since the question then moves to well, who or what created the deity?


  • #3
    branie2
    Registered Users, Registered Users 2 Posts: 10,305 ✭✭✭✭branie2


    I'd go for the big bang as well


  • #4
    WrathOfNothing
    Registered Users Posts: 6 ✭WrathOfNothing


    Thanks. Yeah I get that God is no different really. So was there nothing before the Big Bang? Where did the stuff for the Big Bang come from? That's the bit I don't get.


  • #5
    smacl
    Moderators, Society & Culture Moderators Posts: 15,778 Mod ✭✭✭✭smacl


    WrathOfNothing wrote: »
    Thanks. Yeah I get that God is no different really. So was there nothing before the Big Bang? Where did the stuff for the Big Bang come from? That's the bit I don't get.

    If one big bang doesn't do it for you have a look at the oscillating model. Insane in the brane and all that ;)


  • #6
    nozzferrahhtoo
    Registered Users Posts: 9,348 ✭✭✭nozzferrahhtoo


    WrathOfNothing wrote: »
    Been reading a bit and was wondering if you're not going with God and all that, where did it all come from?

    Built into this is an assumption that such an answer is necessary if you do not "go with god". This assumption is problematic but one I have seen often. That if we do not think a god did it, there must be something else we think.

    For many of us here however the answer is "We do not know". It is currently an open and unanswered question for which we CURRENTLY have no evidence that a god is the answer.
    WrathOfNothing wrote: »
    How can something come from nothing?

    How do you know it did? Why do we assume "nothing" was the default and therefore "something" must be explained?

    Is it not equally valid to assume there always has been a something and that therefore at no point did something actually come from nothing?

    Also I once had two bank accounts each with a 0 balance. However one had an over draft facility so I transferred money from it to the other account and then took money out of my account.

    In a way something came from nothing. Why? Because the sum total of everything, including the money in my hand, was still nothing. And in fact if you listen to lectures from Laurence Krauss it seems recently attempts to add up all the positive and negative energies in our universe is tending towards a sum total result of....

    .... you guessed it......

    Zero.

    So it may in fact turn out our universe is like my student bank accounts. The result of what happens when you get nothing at all, and then split it. It appears like there is something, but gather it all together and there actually isn't.


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  • #7
    robindch
    Moderators, Society & Culture Moderators Posts: 24,420 Mod ✭✭✭✭robindch


    WrathOfNothing wrote: »
    So was there nothing before the Big Bang? Where did the stuff for the Big Bang come from? That's the bit I don't get.
    robindch wrote: »
    The most plausible of the current theories concerning the early universe suggest that time itself "began" at the Big Bang, so the concept of "what happened before" doesn't really apply.
    There was no "before" to exist before the Big Bang, so the question of what existed "before" the Big Bang is not meaningful.

    We know from quantum mechanics that things seem to be able to spring into existence and disappear again without any external input. The Big Bang appears to be the same thing at a far greater scale.


  • #8
    WrathOfNothing
    Registered Users Posts: 6 ✭WrathOfNothing


    nozzferrahhtoo wrote: »
    Built into this is an assumption that such an answer is necessary if you do not "go with god". This assumption is problematic but one I have seen often. That if we do not think a god did it, there must be something else we think.

    For many of us here however the answer is "We do not know". It is currently an open and unanswered question for which we CURRENTLY have no evidence that a god is the answer.
    I was just wondering if there was a currently known answer. Not really assuming there was.
    nozzferrahhtoo wrote: »
    How do you know it did? Why do we assume "nothing" was the default and therefore "something" must be explained?

    Is it not equally valid to assume there always has been a something and that therefore at no point did something actually come from nothing?
    That makes sense. I've heard about stuff popping in and out of existence, I was wondering if it was something to do with that.


  • #9
    WrathOfNothing
    Registered Users Posts: 6 ✭WrathOfNothing


    robindch wrote: »
    We know from quantum mechanics that things seem to be able to spring into existence and disappear again without any external input. The Big Bang appears to be the same thing at a far greater scale.
    How does that happen though? I can't find an answer to that.


  • #10
    nozzferrahhtoo
    Registered Users Posts: 9,348 ✭✭✭nozzferrahhtoo


    WrathOfNothing wrote: »
    I was just wondering if there was a currently known answer. Not really assuming there was. That makes sense. I've heard about stuff popping in and out of existence, I was wondering if it was something to do with that.

    Well as I said the current situation is that we simply do not know. We have no explanation. But the good folks at places like CERN are working on it. Send them your love!

    But the evidence that the answer.... whatever it turns out to be..... involves a sentient intentional non-human agent..... is currently exactly ZERO. There is no reason at this time to suspect a god has anything to do with the explanation we will hopefully some day attain.


  • #11
    seamus
    Registered Users, Registered Users 2 Posts: 68,317 ✭✭✭✭seamus


    WrathOfNothing wrote: »
    How does that happen though? I can't find an answer to that.
    If you do find an answer, a lot of people would be very happy to hear from you :D

    The key here is being happy with "We don't know" being the answer to a given question until we have more information.

    The temptation of theists is to find questions which are seemingly unanswerable and insert "God" as the answer. Really though that's not an answer, it just produces more questions. Just like if you inserted "Magic" or "A wizard" in there.

    "We don't know" is the only intellectually honest answer. It acknowledges that the question is open and doesn't create any additional ones.

    On the actual question, quantum mechanics is the place where the line between reality and mathematics becomes blurred. Mathematics tells us that anything is possible, but for many things the probability of it occurring is really, really small. So small that you can assume it is impossible.

    But when you get down to the scale on which quantum mechanics operates, these ridiculously unlikely things actually start to happen. Not constantly, but regularly enough to make a difference.

    Thus in a classical mechanical system, we have determinism. This is cause and effect. The knowledge that given a set of input parameters, we can know for certain what the output will be. That is, if I leave an empty room and close the door, I can know for certain that an elephant will not be there when I go back in.

    Quantum mechanics is not like this. It's probabilistic. Given a piece of empty space, I cannot know for certain that there will not be a quantum particle there when I look again. I can say what the probability is that it will still be empty, but I cannot say with any certainty.

    In line with the old adage, I'm not explaining it very well because I don't understand it well enough :)
    The good news is that quantum theory and our understanding of it is growing very quickly. If pondering the nature of reality and the burning questions about how things exist and why is something that floats your boat, then diving into quantum physics has a steep learning curve but is well worth it.


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  • #12
    Fourier
    Registered Users, Registered Users 2 Posts: 10,558 ✭✭✭✭Fourier


    Lots of stuff here.

    Currently we don't know what proceeded the fireball of "matter" for lack of a better term that was to be found roughly 13.7 billion years ago. Trillions of years of development might have proceeded it or none at all. Difficult to know. Also there are several features of the early universe we can't currently explain like the lack of gravitational waves. It's possible due to quantum mechanics that the early universe lacks a scientific or mathematical description so we might never know.

    As for how the universe will end, currently it is not known. You'll often read about concepts like entropy etc meaning it will end in Heat Death, but entropy doesn't really make sense for the universe as a whole. Recent observations suggest the universe contains phantom energy, I won't go into the technical details but this means it is very hard to tell how the universe will develop in the future.
    WrathOfNothing wrote: »
    How does that happen though? I can't find an answer to that.
    Things don't really pop in and out of existence, that's a misconception driven by popular science books.
    nozzferrahhtoo wrote: »
    In a way something came from nothing. Why? Because the sum total of everything, including the money in my hand, was still nothing. And in fact if you listen to lectures from Laurence Krauss it seems recently attempts to add up all the positive and negative energies in our universe is tending towards a sum total result of....

    .... you guessed it......

    Zero.

    So it may in fact turn out our universe is like my student bank accounts. The result of what happens when you get nothing at all, and then split it. It appears like there is something, but gather it all together and there actually isn't.
    Just to let you know this is not currently tenable. Krauss's ideas require Energy to make sense in General Relativity in a way that has turned out not to be valid. Also that's just Energy, several other quantities exist like spin, momentum, etc that wouldn't be explained by this.


  • #13
    Fourier
    Registered Users, Registered Users 2 Posts: 10,558 ✭✭✭✭Fourier


    seamus wrote: »
    Quantum mechanics is not like this. It's probabilistic. Given a piece of empty space, I cannot know for certain that there will not be a quantum particle there when I look again. I can say what the probability is that it will still be empty, but I cannot say with any certainty.

    In line with the old adage, I'm not explaining it very well because I don't understand it well enough :)
    The good news is that quantum theory and our understanding of it is growing very quickly. If pondering the nature of reality and the burning questions about how things exist and why is something that floats your boat, then diving into quantum physics has a steep learning curve but is well worth it.
    Yeah the problem is in quantum mechanics it's actually the observation itself that causes the particle to be in a certain position or have a certain spin. In fact even the particles themselves only exist as a result of observations. Your body for instance isn't really made of electrons and protons, that's a mental fiction to help explain observations.
    Quantum Mechanics is written from the perspective of an observer and describes what they can expect to see and the chances of seeing it.
    That's why it might not be possible to apply it to the universe, who would be performing observations on the whole universe?

    I recommended some books here if you want to have a deep dive like seamus said:
    https://www.boards.ie/vbulletin/showpost.php?p=109746993&postcount=537


  • #14
    nozzferrahhtoo
    Registered Users Posts: 9,348 ✭✭✭nozzferrahhtoo


    Fourier wrote: »
    Just to let you know this is not currently tenable. Krauss's ideas require Energy to make sense in General Relativity in a way that has turned out not to be valid. Also that's just Energy, several other quantities exist like spin, momentum, etc that wouldn't be explained by this.

    The point of explaining this to the user is not based on whether it is currently accurate and known or not. But to show the user the KIND of answers that are possible out there and how the narratives that might ultimately answer the questions he asks can be very different to the ones we once had when we started asking.

    We have no final answer on the sum total of adding all those things together. Not least because we simply do not have measurements on most of it. Energy, dark energy, matter, dark matter, gravity and more. But it IS interesting that the results of such endeavours so far have tended in the direction of Zero. Philosophically it opens us up to this interesting idea that "something from nothing" might just be "a whole lot of nothing split in interesting ways".

    But sure, the first thing I asked him for me is more interesting. I am not sure why we assume "nothing" to be the default and seek to explain the "something" we have. This is simply not an assumption we can make, is it? There may have "always" (whatever always even means given the only model of time we currently know of is that of our own universe, within its confines) been something so perhaps the expectation of "nothing" requires explanation.


  • #15
    Fourier
    Registered Users, Registered Users 2 Posts: 10,558 ✭✭✭✭Fourier


    nozzferrahhtoo wrote: »
    The point of explaining this to the user is not based on whether it is currently accurate and known or not.
    Oh I know. Just saying it's not a currently valid explanation.
    nozzferrahhtoo wrote:
    We have no final answer on the sum total of adding all those things together. Not least because we simply do not have measurements on most of it. Energy, dark energy, matter, dark matter, gravity and more. But it IS interesting that the results of such endeavours so far have tended in the direction of Zero.
    They aren't tending to zero. It's an outmoded idea. It was a possibility in the 90s. Not now.


  • #16
    nozzferrahhtoo
    Registered Users Posts: 9,348 ✭✭✭nozzferrahhtoo


    You should put yourself forward for a stage debate with Krauss for sure then :) As both his most recent book, and his most recent talks (by recent I mean 3 to 5 years ago maybe even more recent) are still making the claim in question. Though like me here, he might be making it more as a thought experiment than an actual claim. I would have to go back and re-listen to that stuff I suppose.


  • #17
    Fourier
    Registered Users, Registered Users 2 Posts: 10,558 ✭✭✭✭Fourier


    nozzferrahhtoo wrote: »
    You should put yourself forward for a stage debate with Krauss for sure then :) As both his most recent book, and his most recent talks (by recent I mean 3 to 5 years ago maybe even more recent) are still making the claim in question.
    I know you're joking but conducting science via stage debates with science "personalities" is something I'm not too fond of. The arxiv papers and observations discounting the idea are over a decade old. His idea isn't even mentioned in all cosmology graduate text books.

    Krauss has pushed his position for a long time, despite virtually all other cosmologists agreeing the statement is not only untrue but vacuous. He's similar to Sean Caroll with Many Worlds in this regard: placing their own view in popular books and not explaining the mountains of evidence that makes the majority of other scientists disagree with them. Or especially not showing the arguments that essentially discount their proposals.


  • #18
    robindch
    Moderators, Society & Culture Moderators Posts: 24,420 Mod ✭✭✭✭robindch


    WrathOfNothing wrote: »
    robindch wrote: »
    We know from quantum mechanics that things seem to be able to spring into existence and disappear again without any external input. The Big Bang appears to be the same thing at a far greater scale.
    How does that happen though? I can't find an answer to that.
    It is known that spontaneous - ie, uncaused - creation and destruction of particles takes place and can be seen during the (relatively) well-known Casimir Effect:

    https://en.wikipedia.org/wiki/Casimir_effect

    As to why spontaneous creation + destruction takes place - that's something that, for example, our friends over in CERN are working to figure out.


  • #19
    nozzferrahhtoo
    Registered Users Posts: 9,348 ✭✭✭nozzferrahhtoo


    Fourier wrote: »
    I know you're joking

    Only partly joking, I quite enjoy such debates when both parties are actually capable of having the conversation. As opposed to the debates I used to love but lost interest in a long time ago between actual scientists and creationists like convicted criminal Kent Hovind. Well not "like" Kent Hovind. It mostly WAS Kent Hovind. He had the market for anti evolution debates all but cornered.

    Anyway I think he is too busy feigning off accusations of sexual misconduct these days to engage either way.


  • #20
    magicbastarder
    Moderators, Category Moderators, Arts Moderators, Sports Moderators Posts: 50,212 CMod ✭✭✭✭magicbastarder


    Fourier wrote: »
    Yeah the problem is in quantum mechanics it's actually the observation itself that causes the particle to be in a certain position or have a certain spin. In fact even the particles themselves only exist as a result of observations. Your body for instance isn't really made of electrons and protons, that's a mental fiction to help explain observations.
    that's an explanation i haven't heard before; usually it's that particles exist but exist in a superposition of positions and velocities until observed.
    i'd never seen it claimed before that their very existence required observation?

    as to the question 'can something come from nothing' - no, not on the scale, or scale of experience that a human would be familiar with. you could always switch it around and ask 'why can't something come from nothing?' you don't know the answer till you understand the underlying laws of nature, which we don't (yet).


  • #21
    Fourier
    Registered Users, Registered Users 2 Posts: 10,558 ✭✭✭✭Fourier


    nozzferrahhtoo wrote: »
    Only partly joking, I quite enjoy such debates when both parties are actually capable of having the conversation. As opposed to the debates I used to love but lost interest in a long time ago between actual scientists and creationists like convicted criminal Kent Hovind. Well not "like" Kent Hovind. It mostly WAS Kent Hovind. He had the market for anti evolution debates all but cornered.
    I know what you mean, but Krauss on this topic is more like the latter than the former. He's just espousing an idea outmoded twenty years ago that doesn't get discussed anymore.


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  • #22
    robindch
    Moderators, Society & Culture Moderators Posts: 24,420 Mod ✭✭✭✭robindch


    nozzferrahhtoo wrote: »
    It mostly WAS Kent Hovind.
    And, of course, the wilfully silly Doctor Doctor Ken Ham.


  • #23
    Lantus
    Registered Users, Registered Users 2 Posts: 3,027 ✭✭✭Lantus


    WrathOfNothing wrote: »
    Been reading a bit and was wondering if you're not going with God and all that, where did it all come from? How can something come from nothing? Not saying this as an argument for God, just a bit confused. What are the other explanations? How will it all end up?

    Questions like this are valid but not currently verifiable 100% with scientific knowledge as it stands. All matter originated from the big bang and universal expansion and cooling over billions of years including life like ours.

    But don't get caught in trap of filling in the gaps with ideas like deities that grant wishes. It's an easy route to cope with humanities fear of death which we really don't like to confront hence the smorgous board of ideas to provide an afterlife comfort blanket.

    There are models for what will happen in the future. Expansion to nothing, on contraction back to a single point etc and another big bang.
    All interesting but not helpful in relation to the upcoming environmental disaster.


  • #24
    Fourier
    Registered Users, Registered Users 2 Posts: 10,558 ✭✭✭✭Fourier


    magicbastarder wrote: »
    that's an explanation i haven't heard before; usually it's that particles exist but exist in a superposition of positions and velocities until observed.
    i'd never seen it claimed before that their very existence required observation?
    It's the standard Copenhagen interpretation of Quantum Mechanics.

    Particles only exist as an effect on certain macroscopic devices when they interact with the microscopic world. For example a photo detector will develop dots. So to get a particle you have to do a certain kind of observation.

    What the microscopic world actually consists of is not described by Quantum Mechanics.
    robindch wrote:
    It is known that spontaneous - ie, uncaused - creation and destruction of particles takes place and can be seen during the (relatively) well-known Casimir Effect:
    The Casimir Effect is actually just that the plates attract each other because the Van der Waals forces are stronger than you would naively expect. It was thought in the 1940s that it was due to particles "popping in and out of existence" and unfortunately this idea from the 40s has lingered in popular science books.


  • #25
    Cabaal
    Moderators, Technology & Internet Moderators, Regional South East Moderators Posts: 28,510 Mod ✭✭✭✭Cabaal


    Have always seen the god suggestion as an easy way out as already pointed out by robindch the obvious response is "who created the god?", to which I've been told by numerous religious people that apparently god always existed....this of course is a cop out. After all you could just equally claim the universe always existed without god.

    I guess some people really do fear the unknown and although there is scientific ideas regarding the creation nobody can ever say 100% they are accurate, but thats ok, you can still base the theory on the available evidence.
    I don't fear the unknown, but equally I don't replace the unknown with a god just because its easy to do so.


  • #26
    magicbastarder
    Moderators, Category Moderators, Arts Moderators, Sports Moderators Posts: 50,212 CMod ✭✭✭✭magicbastarder


    Cabaal wrote: »
    Have always seen the god suggestion as an easy way out as already pointed out by robindch the obvious response is "who created the god?", to which I've been told by numerous religious people that apparently god always existed....this of course is a cop out.
    an equally facile response is to point out that if god always existed, for infinity, that he was sitting around for an infinite amount of time before creatig the universe. and you'd have to ask what the hell was he doing to keep himself occupied all that time.


  • #27
    Cabaal
    Moderators, Technology & Internet Moderators, Regional South East Moderators Posts: 28,510 Mod ✭✭✭✭Cabaal


    magicbastarder wrote: »
    an equally facile response is to point out that if god always existed, for infinity, that he was sitting around for an infinite amount of time before creatig the universe. and you'd have to ask what the hell was he doing to keep himself occupied all that time.

    Clearly he/she/it built an ant hill somewhere else and created a star so he/she/it could randomly kill the ants with a magnify glass...good practice for when he/she/it created humans. :D

    God focusing on just earth is sort of equal to all of human civilsation focusing on one ant hill somewhere in Africa


  • #28
    robindch
    Moderators, Society & Culture Moderators Posts: 24,420 Mod ✭✭✭✭robindch


    Fourier wrote: »
    The Casimir Effect is actually just that the plates attract each other because the Van der Waals forces are stronger than you would naively expect. It was thought in the 1940s that it was due to particles "popping in and out of existence" and unfortunately this idea from the 40s has lingered in popular science books.
    The Wikipedia article might need a little updating then - thanks for the correction.


  • #29
    Fourier
    Registered Users, Registered Users 2 Posts: 10,558 ✭✭✭✭Fourier


    robindch wrote: »
    The Wikipedia article might need a little updating then - thanks for the correction.
    The Wikipedia article does mention it in a small section "Relativistic van der Waals force" and does note it is the correct explanation. However the problem is it uses the incorrect explanation for most of the article and only notes the correct explanation briefly in that section.

    The quark page is even worse.


  • #30
    WrathOfNothing
    Registered Users Posts: 6 ✭WrathOfNothing


    Fourier wrote: »
    It's the standard Copenhagen interpretation of Quantum Mechanics.

    Particles only exist as an effect on certain macroscopic devices when they interact with the microscopic world. For example a photo detector will develop dots. So to get a particle you have to do a certain kind of observation.

    What the microscopic world actually consists of is not described by Quantum Mechanics.
    Even more confused now. Surely particles are real? Do we have some idea of what is down there?


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  • #31
    Fourier
    Registered Users, Registered Users 2 Posts: 10,558 ✭✭✭✭Fourier


    WrathOfNothing wrote: »
    Even more confused now. Surely particles are real?
    Funnily enough probably not. In certain experiments you get results that for which the classical idea of atoms and particles is useful, so in those cases and for those applications you can think of things being made of atoms and particles. However in general you cannot because you can set up an experiment where those aren't useful notions.

    So strictly speaking we don't know what you are made of beneath roughly the molecular level, i.e. we can say coffee has caffeine in it but saying caffeine is made of carbon etc seems to be just a useful fiction.
    WrathOfNothing wrote: »
    Do we have some idea of what is down there?
    Not really. In the standard view of QM what's really down there is not amenable to scientific analysis or mathematical description because it is not "mechanical" or "algorithmic", so you probably can't know.


  • #32
    WrathOfNothing
    Registered Users Posts: 6 ✭WrathOfNothing


    Fourier wrote: »
    Not really. In the standard view of QM what's really down there is not amenable to scientific analysis or mathematical description because it is not "mechanical" or algorithmic, so you probably can't know.
    How can there not be a scientific explanation?


  • #33
    robindch
    Moderators, Society & Culture Moderators Posts: 24,420 Mod ✭✭✭✭robindch


    WrathOfNothing wrote: »
    How can there not be a scientific explanation?
    You're aware that humans don't know everything there is to know?


  • #34
    Fourier
    Registered Users, Registered Users 2 Posts: 10,558 ✭✭✭✭Fourier


    robindch wrote: »
    You're aware that humans don't know everything there is to know?
    Perhaps you're encompassing this when you say "don't know", but this goes a bit further into "unknowable in principle". Microscopic systems don't seem to be quantifiable. Whatever is responsible for the behaviour of the sub-molecular world it seems to lie outside of spacetime and not obey quantifiable rules.

    That's not "obey scientific laws we don't know" it's literally "their behaviour is not governed by mathematical rules or laws". This is related to why reductionism breaks down in quantum mechanics.

    I'm trying to think of how to explain it briefly though.


  • #35
    robindch
    Moderators, Society & Culture Moderators Posts: 24,420 Mod ✭✭✭✭robindch


    Fourier wrote: »
    Microscopic systems don't seem to be quantifiable.
    Is 'quantifiable' the right word here? I'd have said that the world of the very small is quantifiable - inasmuch as it's amenable to statistical calculation. That's different however from 'predictable' which seems to be what the wider population expect derives from "scientific knowledge".


  • #36
    Fourier
    Registered Users, Registered Users 2 Posts: 10,558 ✭✭✭✭Fourier


    robindch wrote: »
    Is 'quantifiable' the right word here? I'd have said that the world of the very small is quantifiable - inasmuch as it's amenable to statistical calculation. That's different however from 'predictable' which seems to be what the wider population expect derives from "scientific knowledge".
    What's amenable to statistical calculations is macroscopic responses to the microscopic world. So for instance QM doesn't say there is a (let's say) 40% chance of a particle being located in a certain region, it says that if there is a device (with the correct properties) placed in that region it will light up 40% of the time. However that's not a statistical statement of the subatomic world, just responses from it.

    If the positions, momenta, spins, etc we measured were actual real properties of the stuff down there, then you'd have statistical account. However since they're actually properties of our devices we don't even have that.


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  • #37
    smacl
    Moderators, Society & Culture Moderators Posts: 15,778 Mod ✭✭✭✭smacl


    Fourier wrote: »
    What's amenable to statistical calculations is macroscopic responses to the microscopic world. So for instance QM doesn't say there is a (let's say) 40% chance of a particle being located in a certain region, it says that if there is a device (with the correct properties) placed in that region it will light up 40% of the time. However that's not a statistical statement of the subatomic world, just responses from it.

    If the positions, momenta, spins, etc we measured were actual real properties of the stuff down there, then you'd have statistical account. However since they're actually properties of our devices we don't even have that.

    Excuse the total ignorance of QM but how does that differ from use of transducers in other passive or active forms of measurement such LIDAR, interferometry, tomography etc...


  • #38
    Fourier
    Registered Users, Registered Users 2 Posts: 10,558 ✭✭✭✭Fourier


    smacl wrote: »
    Excuse the total ignorance of QM but how does that differ from use of transducers in other passive or active forms of measurement such LIDAR, interferometry, tomography etc...
    Just explain what seems to you to be the similarity first in more detail. This is just to frame my answer without me rambling.


  • #39
    moonage
    Registered Users Posts: 855 ✭✭✭moonage


    robindch wrote: »
    The most plausible of the current theories concerning the early universe suggest that time itself "began" at the Big Bang, so the concept of "what happened before" doesn't really apply.

    Also, externalizing the creation of the universe to a deity doesn't achieve anything anyway, since the question then moves to well, who or what created the deity?

    The problem with the Big Bang theory is, as Terence McKenna used to say, that modern science is based on the principle, 'Give us one free miracle, and we'll explain the rest'. And the one free miracle is the appearance of all the matter and energy in the universe, and all the laws that govern it, from nothing, in a single instant.

    https://www.youtube.com/watch?v=AATA0TzZf0A


  • #40
    Fourier
    Registered Users, Registered Users 2 Posts: 10,558 ✭✭✭✭Fourier


    moonage wrote: »
    The problem with the Big Bang theory is, as Terence McKenna used to say, that modern science is based on the principle, 'Give us one free miracle, and we'll explain the rest'. And the one free miracle is the appearance of all the matter and energy in the universe, and all the laws that govern it, from nothing, in a single instant.
    The Big Bang model as it exists in cosmology is not an attempt to explain the origins of reality. It's an attempt to explain the large scaled features of the universe from a hypothesised earlier state. It seems to do that pretty well. It's not sensible to say it has a problem because it doesn't explain everything.


  • #41
    magicbastarder
    Moderators, Category Moderators, Arts Moderators, Sports Moderators Posts: 50,212 CMod ✭✭✭✭magicbastarder


    explaining *that* something happened, explaining *how* it happened, and explaining *why* it happened can be three different things.


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  • #42
    smacl
    Moderators, Society & Culture Moderators Posts: 15,778 Mod ✭✭✭✭smacl


    Fourier wrote: »
    Just explain what seems to you to be the similarity first in more detail. This is just to frame my answer without me rambling.

    Ok, so say you have a system like LIDAR. You fire a laser burst in a given direction, you have a light sensitive receptor that looks for a reflection of that laser, you compare the time you fired the laser against the time you get the return, and divide by twice the speed of light to get a distance. You haven't measured the distance to the object directly, you've measured the effect, direct reflection in this case, of placing the object in the path of a laser beam. This usually works but is subject to various interference factors such that it yields a wrong result or no result, e.g. trying to measure to a refractive surface such as water doesn't work well. To improve the result you might take a very large number of repeated measurements and use statistics to get the most likely distance after removing outliers.


  • #43
    Fourier
    Registered Users, Registered Users 2 Posts: 10,558 ✭✭✭✭Fourier


    smacl wrote: »
    Ok, so say you have a system like LIDAR. You fire a laser burst in a given direction....To improve the result you might take a very large number of repeated measurements and use statistics to get the most likely distance after removing outliers.
    Okay well I'll go with two examples from quantum mechanics. The Kochen Specker theorem and Bell's theorem. I'll have to do this in stages rather than all in one go.

    First Bell's theorem.

    Say you have two particles and you can measure their spin in two directions X and Z. That means how much they are spinning about that axis. The spins can be either -1 or 1, clockwise or anticlockwise.

    I'll use the notation XX to denote that you measured the X-direction spin of the first and the X-direction spin of the second. Similarly XZ means X-direction spin of the first and Z-direction spin of the second.

    If I do the measurements I find the following results:
    Measurement|Comparison
    XX|=
    XZ|=
    ZX|=
    ZZ|≠


    This means for example that when I measure X-direction spins for both they are always equal.

    If you look at this there is no possible assignment of values for X and Z for both particles that can make this table true.

    If that makes sense I'll proceed with what this demonstrates and compare it to what you are talking about.


  • #44
    robindch
    Moderators, Society & Culture Moderators Posts: 24,420 Mod ✭✭✭✭robindch


    Fourier wrote: »
    However that's not a statistical statement of the subatomic world, just responses from it.
    Now that you say that, I'm reminded of the double-slit experiment and the multiple interpretations coming from from a single lower-level phenomenon - what you say makes sense, once some head furniture is moved about a bit.


  • #45
    Fourier
    Registered Users, Registered Users 2 Posts: 10,558 ✭✭✭✭Fourier


    robindch wrote: »
    Now that you say that, I'm reminded of the double-slit experiment and the multiple interpretations coming from from a single lower-level phenomenon - what you say makes sense, once some head furniture is moved about a bit.
    What's happening in the double slit experiment is that if you don't place a detector at either of the slits then there is no "fact of the matter" about which slit it went through. Many popular expositions say it went through both, but rather it's that the concept of "which slit the particle went through" is non-applicable. Only concepts you measure have truth values.

    And since there is no fact about how it went through the slits, the screen beyond the slits can develop a pattern that makes no sense in terms of it going through either or both. It's not constrained by a fact about which slit the particle went through.


  • #46
    Morbert
    Registered Users, Registered Users 2 Posts: 3,457 ✭✭✭Morbert


    robindch wrote: »
    The most plausible of the current theories concerning the early universe suggest that time itself "began" at the Big Bang, so the concept of "what happened before" doesn't really apply.

    Also, externalizing the creation of the universe to a deity doesn't achieve anything anyway, since the question then moves to well, who or what created the deity?

    Hmm, I think the traditional cosmological argument, which attempts to deduce god from cosmology (in the philosophical sense of the word), makes a distinction between contingent truths and necessary truths, with only the former having explanations. An interlocutor would say God exists necessarily, while the universe does not.

    They also wouldn't agree that "no time before the big bang" would exempt the universe from warranting an explanation. E.g. Even if some iteration of the Hartle-Hawking no-boundary proposal* eventually turns out to yield a description of our universe, an interlocutor might insist you explain why our universe is in line with this proposal, or any proposal at all.

    My suspicion is the strongest response is to question whether the universe is thoroughly intelligible, and hence whether the principle of sufficient reason is universal.

    *e.g. https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.122.201302


  • #47
    Fourier
    Registered Users, Registered Users 2 Posts: 10,558 ✭✭✭✭Fourier


    smacl wrote: »
    Ok, so say you have a system like LIDAR. You fire a laser burst in a given direction, you have a light sensitive receptor that looks for a reflection of that laser, you compare the time you fired the laser against the time you get the return, and divide by twice the speed of light to get a distance. You haven't measured the distance to the object directly, you've measured the effect, direct reflection in this case, of placing the object in the path of a laser beam. This usually works but is subject to various interference factors such that it yields a wrong result or no result, e.g. trying to measure to a refractive surface such as water doesn't work well. To improve the result you might take a very large number of repeated measurements and use statistics to get the most likely distance after removing outliers.
    If you want a very short answer. The statistics you'll see are consistent with there being a pre-existent value for your measurement, i.e. regardless of whether your measurement was direct or indirect it was going to produce some specific effect in your equipment.

    The statistics you get out of quantum mechanical measurements are not compatible with this. You're forced to conclude that your apparatus created the value and the specific nature of your apparatus is important to what that value is.

    Thus the results of quantum measurements are not you learning something about the microscopic system, they're just reactions in your device.


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