Dear Amanda:

What a nice and provocative essay.

I have one, very basic, question: For concreteness I will focus on the question of observer dependence of the notion of particles. If one looks at Unruh's calculation that gives a thermal spectrum of particles for the accelerated Rindler observer and no particles for the Minkowski observer isn't it true that the calculation starts from the same state in the same space-time for both these observers? While it is true that the two descriptions by the two observers are different it is also true that there is one description from which both of these can be derived.

So why shouldn't I call this one description (Minkowski space R^4 together with vacuum state |0>) the one universe? If you want the description for a particular observer just tell me how she moves and I will tell you what she sees.

I think what I said here for particles remains true for the other examples you cite (with the possible exception of quantum mechanics).

All the best.

Olaf

    Hi Olaf,

    Thanks so much for taking the time to read my essay, and for your great question.

    I agree with you that in the Rindler case, you can think about two observers that start in the same universe, then have radically different but equally correct views of that same universe (rendering particles observer-dependent). As you say, you can translate between them (with a Bogoliubov transformation rather than a Lorentz transformation). That alone doesn't obviously demonstrate the solipsism I'm arguing for, though the observer-dependence of the vacuum (with none being more "true" than another) is kind of the first clue that there is some degeneracy in the nature of the universe. But take the case of an elephant falling into a black hole. An accelerated observer outside the black hole will see the elephant burn up before it crosses the horizon, its ashes radiated back out to infinity. But an inertail observer who falls in with the elephant sees it alive and well inside the black hole before it hits the singularity. If you assume that these two observers occupy one single universe, then it's a universe in which the elephant's quantum state has been cloned, violating the laws of quantum mechanics. If you want to keep the laws of physics intact, you're forced to give up the notion of a single, shared universe and instead restrict to a single observer's frame. I suspect there's a way to make this same argument for a Rindler observer, but it's not as intuitive, since he can always stop accelerating, rejoin the inertial observer and compare notes. Nonetheless, while he is accelerating you would surely violate the laws of physics if you described both their points of view with a single global geometry. This becomes especially relevant when you consider that we live in an asymptotically de Sitter universe, and that each observer has their own event horizon.

    To my mind, this tells us something very powerful. That's not an original insight - I am taking cue from Susskind, Bousso, Banks, etc. Banks in particular argues that we have to generalize this argument to say that physics only makes sense within a single causal patch and that everything outside that observer's horizon should be considered pure gauge. What's original (and undoubtedly controversial!) in my piece is the attempt to connect this view with the low quadrupole in the CMB and with quantum logic.

    Thanks again.

    All best,

    Amanda

    • [deleted]

    With not long to the end of community voting your consideration of my own would be very much appreciated. Kind regards Georgina.

    This is a very original and thought provoking idea, good luck.

    • [deleted]

    Did you rate my essay?

    Dear Amanda

    Very interesting essay! Thanks for the suggestion! Now I could for the first time understand some of the basic ideas about the problem of information in black-holes. But I have a question, if the universe is not shared by all the observer, what is shared by all observers?

    I have some ideas about it that can possibly give you some insight, well I hope so... One of the main problem was that apparently there was information being cloned if you look from to observers at the same time. However, there should be some correlation between any two observers. In this case, the total entropy (or information) will not be the sum of each observer's entropy. Actually I think two observers are completely correlated such that their total entropy equals each one' entropy. This might explain why "we can never speak about more than one at a time." and also why "according to which each observer's reference frame defines a complete universe, and anything outside the frame is considered merely a redundant description.". In information theory, if you add a redundant description the information content is not increased!

    I also agree that the existence of more than one reference frame can lead you to non compatible Boolean logics, each frame has a Boolean logic but the comparison cannot be done using a Boolean logic. But I think this notion is different from the notion of quantum mechanics. I mean, your ideas add something new to quantum mechanics (general relativity reference frames and observers), so they cannot be explained by pure QM, we'll need something new, probably quantum gravity or quantum general relativity.

    Wish you all the best! And good luck on this contest!

    Frederico

    Dear Amanda,

    I liked very much your New Scientist article about mathematics and reality, especially the part about the dodecahedron, it is our consciousness but not in our reality. Tegmaark has some points, especially with the limits of our causal universe and the math's that go untill these limits, it is furtheron that our consciousness takes over and goes ad infintum.

    It was Benjamin Dribus who draw again my attention on your essay (I posted before (september 10) in a post on [link:fqxi.org/community/forum/topic/1370] my thread [/LINK] , regarding the aspect of subjective reality that we both are treating.

    I understand you are very busy, but perhaps you will find a split moment to read and or rate (or comment) my participation.

    best regards

    Wilhelmus

    Hi Amanda -

    I came across this paper today. It's too technical for me, but if you haven't already seen it I think you'll be interested in the introductory section -- as a way of thinking about how the different universes of different observers are connected.

    The Principle of Relative Locality

    Conrad

      Amanda,

      I'd like to pass you a link to the paper I referred above with strong analogies to your work, if you have time to read it and discuss.

      I hope you manage to read my essay first as I look forward to your comments.

      Best wishes

      Peter

      Dear Amanda,

      The New Scientist special issue "WHAT IS REALITY" is very good, the perceptions of Henry Stapp and Matthew Donald have a lot of paralels with my own perception of reality.

      I would like to sent my essay to them, is it possible that you give me their e-mail ,

      mine is

      wilhelmus.d@orange.fr

      If not possible, I understand, but a question is always possible.

      Thanks

      Wilhelmus

      Dear Amanda,

      Wow! Your essay deserves the highest possible note -- and you got a 10 from me -- because it brilliantly explores (In the right direction!) which of our basic physical assumptions are wrong. Many thanks to Ben Dribus, who told me yesterday evening about your excellent essay.

      So I would not argue with you when you "... argue that the basic assumption of a single universe shared by multiple observers is wrong." On the contrary, I fully agree with your perspective, and in my essay From Minkowski's Diagram to the Multispace Model of the Universe I make the first step in the same direction by explaining "why" and most important "how" it happens that this universe is a multispace.

      Yes, as you say, "... each observer lives in their own unique universe", but I realized that telling this fact like that was quite scary for some people, and that they had a tendency to disconnect themselves from my subject. Didn't you notice the same thing?

      So in my essay, I preferred to use 'spacetime reference frames' instead of 'universes' and 'multispace' instead of 'multiverse,' nicely reminding the audience that this confirms Minkowski's 1908 declaration that the world is composed of an infinite number of spaces, as well as his multispace relativity.

      You say "that we must never speak of more than one observer or universe at a time."

      On one side, I completely agree. Each observer exists in his own universe. It is not for nothing that we instinctively feel we live in a 'bubble of perception.' And it's also true that we perceive the surrounding reality through our sense organs, filters that project this reality into our 'bubble universe,' our conscious self. So yes, each of us is 'one observer in his own universe.'

      Yet, on the other side, it's not so simple. When do we start to talk about this 'own unique universe?' Is it the space surrounding our body? If you and me are ten feet away are we still in the same universe? What if we hug each other? If I look at my hand, is it inside or outside my universe?

      Even more, we agree that in a multispace/multiverse world, "... each observer lives in their own unique universe." But each observer -- in fact each of us -- is made out of various organs, cells, and so on until these nagging pieces of matter called elementary particles. Do we have the right to say that quantum spaces are also little universes? After all, besides the size, the only difference between me looking at you through our universes, and seeing you, and looking at an elementary particle through its universe -- its quantum space -- is that I don't see this elementary particle. But there is a simple and very physical explanation for that, which I also advance in my essay From Minkowski's Diagram to the Multispace Model of the Universe.

      In fact, what I want to say is that this essay is just the tip of the iceberg. I spent several years to prove the Multispace Model beyond any possible doubt by finding convincing supportive evidence not just in physics, but also in cosmology and in Earth sciences.

      I hope you have a moment to check it out and share your thoughts with me.

      Best of luck in the contest.

      Eugeniu Alexandrescu

      If you do not understand why your rating dropped down. As I found ratings in the contest are calculated in the next way. Suppose your rating is [math]R_1 [/math] and [math]N_1 [/math] was the quantity of people which gave you ratings. Then you have [math]S_1=R_1 N_1 [/math] of points. After it anyone give you [math]dS [/math] of points so you have [math]S_2=S_1+ dS [/math] of points and [math]N_2=N_1+1 [/math] is the common quantity of the people which gave you ratings. At the same time you will have [math]S_2=R_2 N_2 [/math] of points. From here, if you want to be R2 > R1 there must be: [math]S_2/ N_2>S_1/ N_1 [/math] or [math] (S_1+ dS) / (N_1+1) >S_1/ N_1 [/math] or [math] dS >S_1/ N_1 =R_1[/math] In other words if you want to increase rating of anyone you must give him more points [math]dS [/math] then the participant`s rating [math]R_1 [/math] was at the moment you rated him. From here it is seen that in the contest are special rules for ratings. And from here there are misunderstanding of some participants what is happened with their ratings. Moreover since community ratings are hided some participants do not sure how increase ratings of others and gives them maximum 10 points. But in the case the scale from 1 to 10 of points do not work, and some essays are overestimated and some essays are drop down. In my opinion it is a bad problem with this Contest rating process. I hope the FQXI community will change the rating process.

      Sergey Fedosin

      Please make note of this correction:

      In my essay's section on holographic spacetime, I attributed the theory to Tom Banks. However, it should have been attributed to Willy Fischler as well. My apologies for the omission.

      Many thanks,

      Amanda

      5 days later
      • [deleted]

      Dear Amanda,

      When you say "universe," you appear to mean a classical universe, or a universe described on the basis of finite observations, or a description of a universe recorded using classical information. If this is the case, I believe your statement on p. 7 that "I suspect that this is exactly what quantum mechanics has been trying to tell us all along" is correct - what QM has been trying to tell us all along is that classical descriptions are observer-dependent. This is in one sense not at all surprising: descriptions based on observations could be observer-independent - truly objective - only if the observers involved were effectively omniscient. Classical physics assumes omniscient observers: observers who are correct and complete, up to measurement resolution, in the descriptions that they record.

      That said, I do not believe that you can really define an observer as a reference frame. A reference frame is just an abstraction. Reference frames do not accumulate classical information. At the very least, I think you need to attach to your reference frame a list (possibly just one item long) of classical information and a method for updating the list with newly-acquired classical information. You must, in other words, provide some representation of how classical information is obtained and recorded. See my paper in Information 3 (2012), 92-123 for details.

      The interesting question that emerges from this line of thought is: Is there any sense in which my impression (for example) that other observers 1) exist, 2) record classical descriptions roughly consonant with mine, and 3) engage in meaningful communication with me is accurate? As a realist, my assumption is that multiple observers exist, and that while our multiple descriptions are in some sense incommensurate in principle - we cannot, as you point out, actually inhabit each others' reference frames, and moreover we cannot observationally determine what caused any of our own or other observers' experiences - we nonetheless are all observing and recording classical information about the same (physical, quantum, real) universe. The interesting questions are whether this realist view is sane or insane, and if it is sane, how one can account, physically, for the apparent consonance of observations that allows different observers to (apparently) share both observational beliefs and the languages employed to communicate them.

      Cheers,

      Chris

      2 months later
      • [deleted]

      Amanda: I imagine you were as surprised as I was to win a Special Commendation in this contest. You may recall (above) that I was effusive after reading your essay -- it continues to be my favorite of the lot. So I think it's fascinating, if somewhat unexplainable, that we were both plucked out of the lot and recognized. I believe our essays share profound themes in common, which I didn't get to elaborate upon during the run of the competition. If you might be interested in continuing the discussion, and comparing notes on the contest (I hope you've gotten to read some of the fallout from the winners announcement), feel free to drop me a line at tenrec@pacbell.net. Have a good day.

      10 days later
      • [deleted]

      Will engineers ever benefit from the denial of one common objective reality?

      Already Einstein's special theory of relativity abandoned the at least reasonable common time for the sake of taking the point of view of an individual observer.

      This led to many obvious paradoxes. On the other hand, the vehemently claimed and defended, by a Wikipedia task force, benefits are not really so obvious. Opponents argue they can be explained otherwise too or even better.

      I see in the essay nothing new but nonetheless the provocative style well suited for tabloid journalism.

      Eckard

      15 days later
      16 days later
      • [deleted]

      Dear Amanda

      I just discovered your wonderful article on Cosmic Solipsism, which I've found to be profound in its implications, scientifically accurate, and totally free of erroneous assumptions. This is a remarkable achievement.

      I wonder if you would allow me to reprint the article on my website:

      http://scienceandnonduality.wordpress.com/tag/science-and-nonduality/

      Your article makes the scientific argument for what I have to say much better than I can ever say it.