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The Paradoxes That Threaten To Tear Modern Cosmology Apart
KentuckyFC writes Revolutions in science often come from the study of seemingly unresolvable paradoxes. So an interesting exercise is to list the paradoxes associated with current ideas in science. One cosmologist has done just that by exploring the paradoxes associated with well-established ideas and observations about the structure and origin of the universe. Perhaps the most dramatic of these paradoxes comes from the idea that the universe must be expanding. What's curious about this expansion is that space, and the vacuum associated with it, must somehow be created in this process. And yet nobody knows how this can occur. What's more, there is an energy associated with any given volume of the universe. If that volume increases, the inescapable conclusion is that the energy must increase as well. So much for conservation of energy. And even the amount of energy associated with the vacuum is a puzzle with different calculations contradicting each other by 120 orders of magnitude. Clearly, anybody who can resolve these problems has a bright future in science but may also end up tearing modern cosmology apart.
If there are no particles moving at all, how does empty space have energy? It's the textbook definition of lack of energy. Empty space cannot impart energy on matter and it can't spontaneously create matter. There's some theory about virtual particles but their net energy is zero when they combine so that's not it. Can anyone explain why empty space has energy?
Perhaps the most dramatic of these paradoxes comes from the idea that the universe must be expanding. [...] yet nobody knows how this can occur.
Since when did "paradox" became a synonym for "unknown"?
Yeah, nobody knows how space expands, but how does that make it a "paradox"?
Oliver.
throw-away comment, here :) i did a funny little bit of experimenting a couple of years back, when someone posted here an article about the density of deep space (the number of atoms per cubic metre) having been measured. anyway, remembering my o-level chemisty and i went, "hmm... that's interesting: i wonder if there's a relationship between that particle density and avogadro's constant.
so... i went... density = 7 * 10e-26, avogadro's const = 6.023 * 10e23, multiply the two together you get 4.2154. just for fun take the cube-root and oo! you get 1.6153982. now, to within experimental uncertainty of the measurements made of the density of deep space vacuum, that number should instantly be recogniseable +/- a bit, as the golden mean ratio (1.618 etc etc).
so we have a relationship - which has absolutely no quotes real quotes meaning whatsoever [ traditionally called "numerology" in a disparaging way in the physics community... ] between the density of particles in vacuum, avogadro's constant, and the golden mean ratio, in a formula that has very low kolmogorov complexity (https://en.wikipedia.org/wiki/Kolmogorov_complexity). which, as i do not have the kinds of hang-ups that the physics community has about these kinds of things, i find to be... beautiful.
and that's in and of itself enough for me. i don't care what the physicists say :)
anyway, as this is slashdot, i thought i'd happily derail the conversation with a nice bit of random semi-related nonsense, and see if anyone notices...
Also, I saw the evidence for "modern" physics and I've never been convinced of it. As far as I can tell, the void is filled of all possible particles and matter are the "empty" bubbles breaking the symmetry, that would make possible the transversal waves in the void that killed the ether theory, explain why there is a limit to the speed of anything and would provide a medium of propagation for the forces without falling back to "magic" fields.
It would also provide a framework to explain why there is energy in the vacuum and why the expansion of the universe leaves energy behind (some kind of horizon event taking antimatter and leaving "space" holes behind... that would also explain the matter\antimatter asymmetry in the universe).
Yes, I know. the nobel prize will be shared amongst all ac's that ever posted here
http://www.simulation-argument...
But, that does not make it any less real-seeming to all of us being simulated...
And of course, the universe simulator could be simulated, etc....
It might be simulated turtles all the way down. :-)
A 21st century issue: the irony of technologies of abundance in the hands of those still thinking in terms of scarcity.
It has been known for quite some time that energy is difficult to define rigorously in General Relativity. A good explanation can be found in this post by CalTech physicist Sean Carroll. Key point:
As a simple example, imagine a photon traveling through an expanding universe in a region with no other matter or energy (dark or otherwise). The expansion of space stretches the wavelength of the photon (cosmological redshift, which is distinct from Doppler redshift), causing it to lose energy. The photon loses energy with nothing around it gaining. Energy is lost because spacetime itself is changing, so Noether's theorem doesn't apply.
There's also no evidence that energy is being created.
This!
Given how quantum non-locality appears to work, we can in some cases be forced to consider that the energy in question is distributed until it becomes "not distributed" by some process that collapse it's superposition. Examination by most physical measurement processes does this.
Even though Einstein abhorred the implications of quantum theory, his own general approach to working out relativistic theory stands, which is to base our examinations of the universe on 2 things:
1- That which we observe and can confirm by experiment and
2- The implications of what we observe and can confirm by experiment which then must be observed and confirmed by experiment.
I do agree that there is a point where each explanation ceases to function to explain the whole, newtonian physics functions to explain how macroscopic objects behave to a certain precision and it breaks down when the curvature of spacetime is altered by extreme amounts of mass in a small place or limited masses being accelerated to such speeds that they require descriptions of how they alter spacetime by effect to be described properly. This description breaks down when we attempt to explain objects existing at the sub atomic level and a whole other set of rules come into play that exist in between the frames of the macroscopic and relativistic linear framework we are used to using to describe things. Beyond this we are at the point where we do not have the tools yet to perform experiments we need to test the implications of the things which we have observed at that level.
Sometimes analogies can be helpful, sometimes they can just confuse the issue. In the case of expanding space, I prefer to think of it as something analogous to plate tectonics, We know the Earth is not expanding, but we know that the floor of the Atlantic ocean is getting wider and wider across geologic time scales, matter is not being created, but the distance between the coastlines of the eastern United States and Western Europe gets a little larger each century. When considering vacuum energy I think of the plate tectonics analogy and remember that even though it seems like the vacuum energy should be becoming more vacant, the implications of what we observe in the Hadron collider confirms that when taken altogether, the total amount of energy in the universe balances out to zero and comparing different sized slices of this pie to one another confuse the issue.
IANAP, but my admittedly also very shallow understanding, is that when we're talking about the energy of the "vaccuum", we mean "energy associated with space itself".
A vaccuum is typically defined by the absence of matter in a volume of space (but not necessarily light or other energy). But let's exclude those too - there is no matter or electromagnetic radiation at all.
Even with those exclusions, at a fundamental level space appears to be a seething maelstrom of quantum particles popping in and out of existence. There seems to be some energy associated with "empty" space.
Some people posit that the vaccuum (i.e. space as we know it) may be "unstable" - that the particular energy it possesses could be lower than it is - and that we're just caught on a local bump in the energy landscape. If the vaccuum ever "fell off" that bump to a lower level, it would apparently spread at the speed of light across the entire universe from wherever it started, destroying everything that currently exists, and leaving behind... I don't know what. More vaccuum, but with a much lower energy associated with it, and with lots of new matter and energy created by the release of the vaccuum energy. Probably.
Anway, happy for a real physicist to correct me on some or all of the above - that's just my very lay understanding of what is meant by vaccuum energy.