Like a box of chocolates...
Dec. 11th, 2015 04:41 pm![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
pheloniusfriarYou can tell that I need to be focusing on studying and finishing my last essay for the term, because I keep finding amazing things to do that is not studying and finishing my last essay. Today's reason for turning off my computer (I'm this close) is World Science U. This new site currently features a pair of courses by popularist and educator Brian Greene on Special Relativity (both as an introduction for the generally interested, and as a course heavy in math, but doable by anyone with a high school eduction), a series of "Master Classes" by a number of renowned researchers (in math and physics, but also biology and neuroscience and the nature of consciousness), and a grab-bag collection of "Science Unplugged" short presentations on many questions that people ask about science topics (as they say, "Unscripted. Uncensored.", heh).
The fatal blow for me (fatal blow to my studies productivity) was that they had a Master Class by Andrei Linde, whose ideas are very much part of what led me (forced me?) to abandon my life as a well-paid systems engineer and learn to love Kraft Dinner as a first-time undergraduate student. Sigh... with the promise that the whole thing could be gotten through in a couple of hours, I was up until 5AM this morning (which was only a couple of extra hours of being awake, I had already been working late). So... I took and completed Andrei Linde's "Universe or Multiverse?" Master Class earlier, and now I'm behind on my studies (and writing this blog post to boot). As a note, the lectures are very accessible, and the only math equations he throws up on the screen are just to show their form in comparison to another equation, one does not need to understand what they mean exactly or how to solve them. After each video, there was a fairly pointless "quiz" (multiple choice, completely unchallenging/un-helpful, but I guess shows you actually watched the video), and then you needed to leave an opinion comment on a discussion board to a question they asked. That is the purpose of this blog post, to preserve my answers over here... I present the question, followed by my sleep-deprived answer for posterity (or posterior, depending on your opinion of such things). What I thought particularly noteworthy is that my answers at the end of one section seemed to predict what he would talk about in the next section (which I hadn't watched when I was answering), so I have at least some understanding of the topic (or I've read enough Linde that I know where he's likely to go). What was also fun about the lecture videos (there were only four of them), was that he started out pretty deadpan in the first one and by the third was making very wry (and very Russian) jokes and humorous comments about what he was presenting.
The inflationary theory has been able to provide answers to many questions that were previously thought to be outside the purview of science. Yet, even though our fundamental understanding of the evolution of the universe has progressed significantly, we seem no closer to resolving various key issues, like "What was before the Big Bang?" Do you think we will ever reach a full understanding of questions such as these, or will our progressions in science only expose new unanswerable mysteries?
Two things come immediately to mind: that it is current thinking that we really only know anything about 4-5% (depending on who you talk to) of what the universe is made of (we know nothing about so-called "dark matter" or "dark energy", which comprise 95-96% of the energy content of our universe), and that Planck Energy scales are on the order of 1030 eV (where the Large Hadron Collider can explore into the 1015 eV range). That's a lot of room left to discover things. There is also the historical precedents that as new science stabilizes and is understood, there are always seemingly "little" things that remain unresolved that when looked at become entire new branches of science (and demand new branches of mathematics). So, we will never reach a full understanding of our universe, but we will continue to peel away layers to expose new mysteries... which may be answered in time as well, but are unanswerable in their day.
In the multiverse, different physical regions are so far apart and independent that residents in a given region might not ever even be capable of finding direct evidence that any other regions exist. What do you think about the burden of proof in this situation? Do you side with those who say the theory is impossible to disprove, or impossible to prove? Or do you land somewhere in the middle?
This questions is reminiscent of the Smolin vs. Susskind argument about whether there was any merit to the notion that our universe is the way that it is because if it wasn't we wouldn't exist the way that we do (the "anthropic principle"). Another form of the argument is that we live in a part of a multiverse that has the parameters needed for our visible universe to exist the way that it does and perhaps other sections of the multiverse (in different states or having experienced different conditions of ongoing formation) could not look the way our universe does (again, it's the anthropic principle: we see what we see because if it wasn't this way, we wouldn't exist in the particular form that we do). I am hopeful that there will eventually be some higher order prediction that we might be able to observe that could only be the way it is if our universe had been in contact with another universe (let's say) at one time that evolved differently from ours. Since inflation as it stands is still a relatively young notion, I think it's possible that we will ultimately come up with a way to at least place limits on what the initial conditions of our universe looked like. Another possible angle is if our universe came into being on the remains of a previous universe, perhaps there are traces we could find in the structure of ours that hint that there may be some existing foundations upon which our edifice was built over. In brief, if our universe ever had an interaction with another part of the multiverse, there should be some trace.
In 1973, physicist Brandon Carter introduced the idea of the anthropic principle. While there are many variations of the principle, they mostly hinge on the idea that there are many universes and that physical laws can vary from one universe to another. In some universes, the physical laws are hospitable to life as we know, but in some universes they’re not. In seeking an answer to why the laws we observe have their particular form, anthropic reason replies that there is no first principles explanation — the laws can and do vary from universe to universe. We see our laws we do because had they been different they’d be incompatible with life, and so we wouldn’t be here to observe them. Do you find this convincing? Circular? Do you think anthropic reasoning has a place in scientific thinking?
The anthropic principle is simply a version of "it just is", which is not a very satisfying argument to me (even though I think it is correct). One of the fascinating things about Linde's explanations is that it goes a little bit further to suggest "why it just is" (why our universe seems to be so suited for our existence). Ultimately, it is true that if there is no scientific mechanism to prove or disprove a theory, then it is just a philosophical argument with no scientific merit; however, at least this principle does pose a question that begs investigation. Even if we can't prove (or disprove) the anthropic principle now, simply proposing it starts a conversation and perhaps some day, some very clever experimentalist will figure out a way of giving it a poke and seeing if there is some substance to the notion. As Linde stated in an earlier lecture, he once would not have believed that the BICEP2 instruments were possible, but gravitational waves were posited and someone eventually figured out a way to build an instrument that might be able to see them (indirectly) if they existed.
One can argue that our universe appears to be finely tuned. For example, had the energy density in the early universe been much lower (and negative), the universe would have rapidly collapsed; were it higher, the universe would have expanded so quickly that galaxies would have never formed. Is it asking too much of science to explain such features? Should we accept them as lucky accidents? Or, as some would argue, acts of divine providence?
Explaining such features is exactly why science exists. Will we be able to answer these seemingly ultimate questions through science? To presume otherwise is doing a grave disservice to our collective ability to find answers; however, to presume that we must be able to find answers to these (and all later) questions sounds like hubris to me as well. Often, it just turns out that when we can't answer a question it is because we have asked something nonsensical and need to go through a long and difficult process to realize what questions we should actually be asking (writing that, I thought of the fictional story Hitchhiker's Guide to the Galaxy... where they found The Answer to the universe, but eventually realized they didn't know what the question was). So far, new ideas and their subsequent refinement has been able to produce very powerful tools and models to describe so many of the phenomena we see and can measure. Eventually there will be a breakthrough that we can't foresee now that will give us new insight into what new questions we should be asking (sometimes modelling things with laboratory systems that we do not have the ability to observe directly gives us the insights and/or proofs we need... for example, using Bose-Einstein condensates in a lab to mimic some of the predicted behaviours of black holes). Perhaps these new questions and answers will eventually lead to answers to these very large (very likely refined-over-time) questions.
In this Master Class, Prof. Linde remarks on the challenges in proving the inflationary multiverse. If an infinite number of different universes can be produced, each with different laws of physics, it seems impossible to design an experiment that could falsify the theory. In a given era, is it acceptable to say a theory is wrong if we cannot conceive of a way to prove or disprove it? Should a theorist simply follow their intuitions when no measurable data might be forthcoming?
If that intuition can provide potential insights into why something might be the way it is, then there is tremendous value into pursuing that line of thought. Intuition is how breakthroughs are made, but it still has to survive criticisms leveled against it to continue to be a valuable idea. Just like intuition can suggest a solution to a problem (even when it can't be tested in any way that we current know), there are others who can apply their intuition to figure out ways the original idea might be wrong, or how it can be made more robust. The worst case scenario is that an internally self-consistent fiction is constructed that turns out to be utterly wrong, but Linde's argument that to unseat a potentially faulty hypothesis requires that a better hypothesis be put forward is a good one. If nothing else, currently unprovable theories challenge those that are bothered by such things to figure out something that can be tested (or ways that the theory might be disproved conclusively or at least seriously limited).
A note on the video: sadly, the BICEP2 results were contested due to new data from the PLANCK satellite (which had not been published at the time of this result), but it doesn't necessarily say that the results were not observations of gravitational waves, but that we can't be sure that's what we're seeing (it could also be polarization from the fact that there's more galactic dust out there than we thought, which is what PLANCK observed). I think it's a good intro to the kind of person Linde is though anyway: observe that he states (even though he was told the results were unassailably true), "if this is true"... ;).
The fatal blow for me (fatal blow to my studies productivity) was that they had a Master Class by Andrei Linde, whose ideas are very much part of what led me (forced me?) to abandon my life as a well-paid systems engineer and learn to love Kraft Dinner as a first-time undergraduate student. Sigh... with the promise that the whole thing could be gotten through in a couple of hours, I was up until 5AM this morning (which was only a couple of extra hours of being awake, I had already been working late). So... I took and completed Andrei Linde's "Universe or Multiverse?" Master Class earlier, and now I'm behind on my studies (and writing this blog post to boot). As a note, the lectures are very accessible, and the only math equations he throws up on the screen are just to show their form in comparison to another equation, one does not need to understand what they mean exactly or how to solve them. After each video, there was a fairly pointless "quiz" (multiple choice, completely unchallenging/un-helpful, but I guess shows you actually watched the video), and then you needed to leave an opinion comment on a discussion board to a question they asked. That is the purpose of this blog post, to preserve my answers over here... I present the question, followed by my sleep-deprived answer for posterity (or posterior, depending on your opinion of such things). What I thought particularly noteworthy is that my answers at the end of one section seemed to predict what he would talk about in the next section (which I hadn't watched when I was answering), so I have at least some understanding of the topic (or I've read enough Linde that I know where he's likely to go). What was also fun about the lecture videos (there were only four of them), was that he started out pretty deadpan in the first one and by the third was making very wry (and very Russian) jokes and humorous comments about what he was presenting.
The inflationary theory has been able to provide answers to many questions that were previously thought to be outside the purview of science. Yet, even though our fundamental understanding of the evolution of the universe has progressed significantly, we seem no closer to resolving various key issues, like "What was before the Big Bang?" Do you think we will ever reach a full understanding of questions such as these, or will our progressions in science only expose new unanswerable mysteries?
Two things come immediately to mind: that it is current thinking that we really only know anything about 4-5% (depending on who you talk to) of what the universe is made of (we know nothing about so-called "dark matter" or "dark energy", which comprise 95-96% of the energy content of our universe), and that Planck Energy scales are on the order of 1030 eV (where the Large Hadron Collider can explore into the 1015 eV range). That's a lot of room left to discover things. There is also the historical precedents that as new science stabilizes and is understood, there are always seemingly "little" things that remain unresolved that when looked at become entire new branches of science (and demand new branches of mathematics). So, we will never reach a full understanding of our universe, but we will continue to peel away layers to expose new mysteries... which may be answered in time as well, but are unanswerable in their day.
In the multiverse, different physical regions are so far apart and independent that residents in a given region might not ever even be capable of finding direct evidence that any other regions exist. What do you think about the burden of proof in this situation? Do you side with those who say the theory is impossible to disprove, or impossible to prove? Or do you land somewhere in the middle?
This questions is reminiscent of the Smolin vs. Susskind argument about whether there was any merit to the notion that our universe is the way that it is because if it wasn't we wouldn't exist the way that we do (the "anthropic principle"). Another form of the argument is that we live in a part of a multiverse that has the parameters needed for our visible universe to exist the way that it does and perhaps other sections of the multiverse (in different states or having experienced different conditions of ongoing formation) could not look the way our universe does (again, it's the anthropic principle: we see what we see because if it wasn't this way, we wouldn't exist in the particular form that we do). I am hopeful that there will eventually be some higher order prediction that we might be able to observe that could only be the way it is if our universe had been in contact with another universe (let's say) at one time that evolved differently from ours. Since inflation as it stands is still a relatively young notion, I think it's possible that we will ultimately come up with a way to at least place limits on what the initial conditions of our universe looked like. Another possible angle is if our universe came into being on the remains of a previous universe, perhaps there are traces we could find in the structure of ours that hint that there may be some existing foundations upon which our edifice was built over. In brief, if our universe ever had an interaction with another part of the multiverse, there should be some trace.
In 1973, physicist Brandon Carter introduced the idea of the anthropic principle. While there are many variations of the principle, they mostly hinge on the idea that there are many universes and that physical laws can vary from one universe to another. In some universes, the physical laws are hospitable to life as we know, but in some universes they’re not. In seeking an answer to why the laws we observe have their particular form, anthropic reason replies that there is no first principles explanation — the laws can and do vary from universe to universe. We see our laws we do because had they been different they’d be incompatible with life, and so we wouldn’t be here to observe them. Do you find this convincing? Circular? Do you think anthropic reasoning has a place in scientific thinking?
The anthropic principle is simply a version of "it just is", which is not a very satisfying argument to me (even though I think it is correct). One of the fascinating things about Linde's explanations is that it goes a little bit further to suggest "why it just is" (why our universe seems to be so suited for our existence). Ultimately, it is true that if there is no scientific mechanism to prove or disprove a theory, then it is just a philosophical argument with no scientific merit; however, at least this principle does pose a question that begs investigation. Even if we can't prove (or disprove) the anthropic principle now, simply proposing it starts a conversation and perhaps some day, some very clever experimentalist will figure out a way of giving it a poke and seeing if there is some substance to the notion. As Linde stated in an earlier lecture, he once would not have believed that the BICEP2 instruments were possible, but gravitational waves were posited and someone eventually figured out a way to build an instrument that might be able to see them (indirectly) if they existed.
One can argue that our universe appears to be finely tuned. For example, had the energy density in the early universe been much lower (and negative), the universe would have rapidly collapsed; were it higher, the universe would have expanded so quickly that galaxies would have never formed. Is it asking too much of science to explain such features? Should we accept them as lucky accidents? Or, as some would argue, acts of divine providence?
Explaining such features is exactly why science exists. Will we be able to answer these seemingly ultimate questions through science? To presume otherwise is doing a grave disservice to our collective ability to find answers; however, to presume that we must be able to find answers to these (and all later) questions sounds like hubris to me as well. Often, it just turns out that when we can't answer a question it is because we have asked something nonsensical and need to go through a long and difficult process to realize what questions we should actually be asking (writing that, I thought of the fictional story Hitchhiker's Guide to the Galaxy... where they found The Answer to the universe, but eventually realized they didn't know what the question was). So far, new ideas and their subsequent refinement has been able to produce very powerful tools and models to describe so many of the phenomena we see and can measure. Eventually there will be a breakthrough that we can't foresee now that will give us new insight into what new questions we should be asking (sometimes modelling things with laboratory systems that we do not have the ability to observe directly gives us the insights and/or proofs we need... for example, using Bose-Einstein condensates in a lab to mimic some of the predicted behaviours of black holes). Perhaps these new questions and answers will eventually lead to answers to these very large (very likely refined-over-time) questions.
In this Master Class, Prof. Linde remarks on the challenges in proving the inflationary multiverse. If an infinite number of different universes can be produced, each with different laws of physics, it seems impossible to design an experiment that could falsify the theory. In a given era, is it acceptable to say a theory is wrong if we cannot conceive of a way to prove or disprove it? Should a theorist simply follow their intuitions when no measurable data might be forthcoming?
If that intuition can provide potential insights into why something might be the way it is, then there is tremendous value into pursuing that line of thought. Intuition is how breakthroughs are made, but it still has to survive criticisms leveled against it to continue to be a valuable idea. Just like intuition can suggest a solution to a problem (even when it can't be tested in any way that we current know), there are others who can apply their intuition to figure out ways the original idea might be wrong, or how it can be made more robust. The worst case scenario is that an internally self-consistent fiction is constructed that turns out to be utterly wrong, but Linde's argument that to unseat a potentially faulty hypothesis requires that a better hypothesis be put forward is a good one. If nothing else, currently unprovable theories challenge those that are bothered by such things to figure out something that can be tested (or ways that the theory might be disproved conclusively or at least seriously limited).
A note on the video: sadly, the BICEP2 results were contested due to new data from the PLANCK satellite (which had not been published at the time of this result), but it doesn't necessarily say that the results were not observations of gravitational waves, but that we can't be sure that's what we're seeing (it could also be polarization from the fact that there's more galactic dust out there than we thought, which is what PLANCK observed). I think it's a good intro to the kind of person Linde is though anyway: observe that he states (even though he was told the results were unassailably true), "if this is true"... ;).
no subject
Date: 2015-12-12 06:26 pm (UTC)no subject
Date: 2015-12-12 11:49 pm (UTC)You're welcome.
Heh ;)