Monday, June 14

Brane Damage And The Big Bang … (No, That’s Not A Typo)

My thanks to Rev. John Heagle for pointing out to me a New York Times link to cosmology, superstring theory, and "relative state" cosmology that led to this column. Fr. Heagle is a one-man instantiation of what the Catholic Church should be, in terms of integrity, spirituality, justice, inquisitiveness ... and just plain indomitable good humor. Being friends with him is like being friends with the late Thomas Merton.

I have been thinking a lot lately about landscapes.  Now, by “landscapes” in this context, I do not mean physical landscapes like the ones painted by, e.g., Albert Bierstadt, members of the Hudson River School, or Monet’s haystacks, etc.  I mean landscapes that result from the possibility that other Universes, other Kosmoi, may exist other than the one we see around us.  You can think of the Great Landscape as a collection of lower-case-l landscapes, immense in number and quite likely infinite, of hills and valleys, each hill representing a possible Universe whose laws and physical constants are different from ours. (The Great Landscape is also referred to in the literature as the “Multiverse”.) I have been brooding about this during the couple days my wife and I were snowed in because of an early-February snowstorm. The snowstorm was quite mild by Pacific Northwest standards, but it did afford enough quiet to reflect on such things. (If the snowstorm had been part of the Polar Vortex, I might have been able to derive a fully renormalizable theory of quantum gravity!) Anyway, my musings led to a question I found fascinating. But to do justice to the question, some background is necessary. I ask your indulgence in what follows …

Julia set

A good place to start would be with the provocative theory of “alternate universes” – popularly  known as the “many-worlds interpretation of quantum mechanics”. Or, more technically, the "relative state" interpretation of quantum theory. The “many-worlds” interpretation of quantum theory is one of the more radical attempts to arrive at an interpretation of what actually happens when the “state vector” collapses. No one knows whether it is true or not. In fact, it is not clear what kind of experiment could falsify "many worlds" quantum theory. All we know is that the math is consistent with experiment. So the following is purely speculative. The state vector is an array of probabilities for the position of a given subatomic particle, probabilities that are predicted by the time-dependent Schroedinger equation.  Until an actual empirical observation of the particle is performed, this array of probabilities continues to evolve over time – hence “time-dependent”. But when a physical observation of the particle is performed, the state vector collapses, and one and only one of the previously-only-potential positions is realized. Hence the term, “collapse of the state vector”. (The above remarks apply to the momentum of the particle.) The question begged is “What is so magical about the intervention of human consciousness via the performance of a physical, empirical measurement?” Does human consciousness have some mystical property that causes previously unknown quantities like the position (or momentum) of a particle to suddenly become sharply defined? Furthermore, what if I do not communicate my measurement to my research colleagues for, say, a week? Presumably, as long as they are not conscious of the results of my measurement, the potential values of the state vector continue to evolve for them, and their state vector only collapses when I notify them of the results of my measurement. Such a conclusion would seem to violate the principle of no privileged points of view in the Universe, i.e., that the Universe looks essentially the same to everyone in any location. That would not be true if I were privileged for a week to be the observer of the particle’s position.

'Omuamua -- artist's conception

(So, yes, one could write the history of science in terms of humans moving farther and farther away from any position of privilege in the Universe. In biology, e.g., humans once thought that they were privileged by having been specially created by God to "have dominion," as Genesis says, over Creation ... until Darwin published Origin of Species in 1859. Then we realized -- though some of us still have not -- that humans occupy no privileged position in the Web of Life. Science fiction, e.g., Carl Sagan's epic novel Contact, extends this conclusion by populating entire galaxies with a veritable zoo of intelligent species, many highly advanced. Problem is, there is no evidence (so far?) that such a zoo really exists. But, as far as we know at present, there is one privileged position,  notwithstanding:  the position of sentient beings, i.e., us, Pascal's "thinking reed". There is no evidence so far for other sibling intelligent species … unless the recent furor over the sighting of a rather anomalous object whizzing past Jupiter – ‘Oumuamua: “scout” in Hawaiian – should prove to be of intelligent origin. Should that turn out to be the case, we would lose even this final privileged position: once again, there would be nothing special about us. We would no longer be a "zoo" of one.)

The “many-worlds interpretation” / relative-state formulation of quantum theory cuts the Gordian knot by restoring the “no privileged position” principle. It does this by insisting, with jaw-dropping  consistency, that all possible values of all possible parameters represented by the state vector are realized and that none drop out. In other words, relative-state quantum theory asserts that all possibilities latent in the mathematical formalism of quantum theory represent, not only possible worlds, but actual worlds – actual universes. Every nanosecond, the Universe is splitting into – pardon the technical terminology – mega-ba-jillions of Universes, i.e., one Universe for each discrete possibility allowed by the state vector of all particles everywhere. Everything that can happen does happen – each nanosecond, all the time. (I use “nanosecond” metaphorically to represent the shortest possible physically realizable interval of time. There is some theoretical justification for believing that to be true, but let’s not go there now, shall we?) So, indeed, no one’s position is privileged, because everything that can happen is, not only equally probable, but equally actual, i.e., with a probability of unity, in some universe or other of the Multiverse. It is like an election where, not only all candidates, but all possible candidates end up being elected. According to the US Constitution, I am a possible candidate for President of the United States, therefore there is a Universe in which I am President. Not only are all things possible, all things are actual. Somewhere or other. In some Universe or other.

Calabi-Yau manifold ... no ... don't ask

If you want to read a more comprehensive, but still accessible – well … more or less … -- account of landscapes and the Landscape, you can do no better than to download a copy of Lee Smolin’s The Trouble with Physics. This is Smolin’s critique of string theory, which he regards as siphoning away physics talent from the overly rarefied and philosophically problematical enterprise of string theory, and leaving equally important but more empirically tractable areas of physics neglected. (I agree with his position here. I used to be enthusiastic about string theory, but the deeper I got into the math, what little of it I can understand, the more impelled I was to ask questions like “How the HAY-YULL are we to ever derive falsifiable conclusions?” But that is beside the point for now:  another rant for another time, as I am fond of saying.) Anyway, Smolin really bangs away about landscapes and the Landscape. He allows that it is quite possible that, when one universe collides with another, that the result can be a Big Bang comparable to the one that occurred 13.8 billion years ago and kick-started our universe. (This conclusion is also an elegant consequence of inflationary models of the Big Bang, but -- again -- another rant for another time.) Furthermore, if such a collision happened once, there is nothing to say it has not happened before with other universes, that it is still happening, and that each time, somewhere or other, infant universes are being created out of the cosmically sexual congress of colliding universes. Cosmic eroticism. Furthermore, each time a new Big Bang occurs, the resulting universe emerges from its own fiery Big-Bang womb with its own collection of physical constants, its own collection of natural laws, etc., etc., etc., etc., and in no such case is there any necessary reason for supposing that those laws and those constants are the same as ours. Why? Because – again – everything that can happen does happen.

Example of gravitational lensing

This idea of new universes being birthed from other Big-Bang events has a kind of elegant consistency with the history of science on our own tiny planet. There was a time when we thought our own sun was the only star in the universe. Then we saw other suns and realized that we were really not so special, after all.  Then we comforted ourselves with the belief that, granted there are other suns, but the Milky Way Galaxy was what we used to refer to as an “island universe”, i.e., that the Milky Way Galaxy simply was the entire universe, and that those strange smudges of light we observed through our telescopes were just immense clouds of luminous gas no doubt fluorescing as they were illuminated by the energy of the ambient stars. But then, in the 1930s, thanks to Messrs. Lemaitre and Hubble, we discovered that those odd blurs of light were not light within our Galaxy at all, but instead were themselves other galaxies – “island universes” – in their own right, and that they were located, not within our Galaxy, but at distances measured in dozens to thousands of millions of light-years.  So again, we turned out not to be so special. Now, today, we are still accustomed to use a definite article when referring to our universe, i.e., the universe.  But “many-worlds” quantum theory, coupled with string theory, holds out the possibility – so far, that is all it is – that our very universe may be one of a most-likely-infinite number of universes populating the Landscape / Multiverse. There is also theoretical justification for the existence of alternate universes in the mathematical formalism of inflationary cosmology, about which you can learn from a recent issue of  Astronomy magazine's discussion of the 50 greatest scientific mysteries, but which I have too little time, and even less  understanding, to explore here.

So far, so good. Now to my question … Suppose that whole universes – technically, I should say “11- or 16-dimensional branes [shorthand for membranes]” – collide and that such collisions result in stupendous explosions on a scale comparable to our own Big Bang. (You might think of this as “brane damage” … or not … OK … sorry.) The resulting universe emerges from that primeval fire with its own physical constants, its own physical laws, in other words, its own identity. My question, to which no one knows the answer, as far as I am aware, is the following:

Fr. Georges LeMaitre
Edwin P. Hubble

Are there laws – call them “meta-laws,” i.e., higher-level laws – that constrain the values of the physical constants that can emerge from the fire of a new Big Bang? Ditto laws:  are there meta-laws that constrain the way the laws emerging from a new Big Bang can operate?

If so, how do values of constants and the operations of physical laws get defined? Is it simply random chance? Is it random chance that, e.g., the speed of light is 300,000 kilometers per second and not 400,000 km / sec? Could there be a universe where the speed of light is 300 miles per hour? Could there be a universe where the baby-universe equivalent of Newton’s inverse-square law was an inverse-cube law? Or an inverse-fourth-power law? Could there be a baby universe where Newton’s gravitational constant was ten trillion times the value it has in our universe? (If the latter possibility were the case, stars would burn out a lot faster, and so life might not have time to evolve -- but even that conclusion presupposes that the laws of biology and chemistry were the same in that alternate universe.) Or one ten-trillionth the value? (In which case, stars might never condense from the cosmic medium, but even that assumes that, e.g., the strong nuclear force would work the same in the alternate case.) We just do not know.

Are some universes simply physically impossible because the regnant meta-laws would not permit them to exist? Remember: the rule is that everything that can happen does happen, not that everything can happen, period. The entire meta-law question amounts to asking if there are constraints on what can happen, i.e., can certain things simply not happen?

Note that this question also has deep implications for the scope of any possible future unification theory. Unifying the four forces of nature – gravitation, weak force, strong force, electromagnetic force -- is expected to entail that the constants that characterize our universe – the speed of light, Newton’s constant, etc. – simply “fall out” of the theory as a logical consequence, and do not have to be, as presently, empirically / observationally discovered. (We do not have to discover empirically that the sum of the angles of a triangle is 180 degrees, that is an immediate consequence of geometry … at least geometry on a “flat” plane.) That may well be possible in our cosmos, but will it necessarily be true across the upper-case-L Landscape of the Multiverse? It may well turn out that we can only unify our own world, not others. Or alternatively, other universes may require other unification theories. Note that all these questions are questions that are pertinent to our Universe, regardless of whether sister Universes exist or not.

Anyway, it is dinner time. I am hungry. And my wife and I are having great landscapes of spaghetti and meatballs. Bon appetit!

James R. Cowles

Image credits

Alternate earths ... Pixabay ... Public domain
Calabi-Yau manifold ... A. J. Hanson ... Creative Commons Attribution -- Share Alike 2.5 Generic
Messier 82 ... NASA ... Public domain
Julia set ... Adam Majewski ... Creative Commons Attribution-Share Alike 3.0 UnportedNGC 4981 ... European Southern Observatory ... CC BY 4.0
Star field ... NASA - Spitzer Space Telescope ... Public domain
Gravitational lensing ... NASA - Hubble Space Telescope ... Public domain
'Omuamua (artist's conception) ... European Southern Observatory ... Public domain
Georges LeMaitre ... Tonynetone ... CC BY 2.0
Edwin P. Hubble ... Johan Hagenmeyer ... Public domain


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