Neil Turok has been with the men who receive got spent years yesteryear hyping theories well-nigh "cyclic universes" as well as related laymen's ideas that receive got never explained anything inwards physics as well as that are genuinely non capable of explaining anything, for really adept reasons. So this firm became a religious action of a sort – he needs to pose out novel papers precisely to create the illusion that the previous papers weren't a stupid waste product of time.
The latest, 5-pages-long newspaper yesteryear Boyle, Finn, as well as Turok is called
CPT symmetric universe.The nascency of a universe from zilch is bad, they effectively claim. Instead, the universe should hold upward pair-created. It's the universe as well as the anti-universe that are created out of zilch which is nicer. The pair, universe summation anti-universe, are supposed to preserve the CPT. The anti-universe is interpreted equally the "universe earlier the Big Bang", they propose.
Concerning the anti-universe, I tin displace never neglect to quote a favorite joke of mine which I learned from my diploma adviser inwards Prague. Aside from the universe, at that spot also exists the anti-universe where everything is anti-. For example, the hardest scientific discipline over at that spot is anti-physics as well as it's researched yesteryear anti-Semites. ;-)
OK, allow us provide to the Turok et al. paper.
First, if they desire to really preserve the CPT, so the "anti-universe" must hold upward a precise re-create of the "universe". So it's precisely a redundancy, a mirror icon added to the history of the "universe", as well as there's no extra data inwards it. So it should hold upward removed. There is no analogy with particles as well as antiparticles because when a particle span is created, the 2 members of the span may undergo unlike fates.
Clearly, they must hateful an "approximate anti-universe" which is precisely macroscopically similar but whose events aren't exact mirror images of the events inwards our "universe". So CPT is even so violated, although inwards some macroscopic perspective, it's to a greater extent than or less preserved.
Second, there's a enquiry whether the "anti-universe" should hold upward drawn equally some history for \(t\gt 0\), equally the normal "universe", or equally \(t\lt 0\). They explicitly advise the latter. But that can't hold upward consistent with the claim that CPT is saved from spontaneous breaking. Why? Because the 2nd police clit of thermodynamics (not to lift related consequences of the arrow of time) demands the entropy to increase with time.
So either they volition receive got the entropy that is an fifty-fifty component of time\[
S(-t) = S(t)
\] inwards which instance the entropy is decreasing at \(t\lt 0\) as well as they violate the 2nd police clit of thermodynamics. Or\[
S(-t) \neq S(t)
\] inwards which instance the development of the "anti-universe" violates the CPT as well as their claim well-nigh the preservation of CPT is wrong. You precisely can't obey the 2nd police clit as well as "spontaneously unbroken CPT" simultaneously!
They included 1 curt paragraph well-nigh the 2nd police clit of thermodynamics:
Also banking concern notation that density pertubations grow equally nosotros acquire farther from the strike inwards either direction, as well as thus the thermodynamic arrow of fourth dimension points away from the strike inwards both directions (to the futurity as well as past).This paragraph automatically includes a violation of the 2nd police clit of thermodynamics. To allow the rules of the thermodynamics to hold upward "reversed" inwards the "anti-universe" is genuinely airheaded because the futurity must hold upward defined equally the side of the temporal axis where the entropy is higher than inwards the past. So if yous receive got 2 parts of the universe where the entropy grows if yous acquire farther away from the Big Bang, so the right manner to depict these "two universe" on the \(t\)-axis is to depict both of them equally branches of \(t\gt 0\).
That motion painting way that at \(t=0\), 2 universes are precisely created out of zilch as well as they may hold upward considered anti-objects of each other. Well, it's unlike from how they desire to spin it. On acme of that, if some universal laws principle the span creation, so the 2 universes are precise "anti-objects" to each other. They must hold upward perfectly entangled as well as they're precisely 2 copies of the same Universe.
At whatever rate, the events inwards the "anti-universe" cannot perhaps acquit upon us because that "anti-universe" is precisely a parallel universe that is forever detached from ours. If yous depict the "anti-universe" equally a branch at \(t\gt 0\), it's clear that this branch inwards no meaningful manner occurred "before our time", so the events inwards that branch can't hold upward considered causes of anything nosotros may observe.
To generalize the prefix "anti-" from antiparticles as well as anti-Semites to the universes could receive got been a adept sentiment a priori. But if yous expect at the basic possibilities, yous tin displace see that it is genuinely non a adept idea. While it's really useful to beak well-nigh antiparticles, antibranes, anti-instantons, as well as other things, it's non useful to beak well-nigh anti-universes.
Influenza A virus subtype H5N1 argue why "anti-" is airheaded for the whole universe is only the fact that, equally Richard Feynman as well as John Wheeler figured out, an antiparticle is a particle moving backwards inwards fourth dimension (perhaps 1 with the negative energy, equally it happens inwards the context of the Feynman diagrams). So to beak well-nigh "anti-", 1 needs a pre-existing notion of fourth dimension as well as its arrow (which is needed either directly, for the directions of time, or indirectly, for the signs of energy, or both).
So exclusively things that may hold upward embedded inside a spacetime with a well-defined arrow of time – e.g. particles as well as branes – may hold upward associated with their anti-objects. The whole universe itself isn't 1 of these things because the universe doesn't be equally an object embedded inside (another?) universe with a well-defined arrow of time.
But none of these things is genuinely understood yesteryear most of the laymen. Turok et al. wrote a confusing packet of some basic exciting notions – anti-stuff as well as Big Bang – as well as tons of stupid people volition purchase this slice of popular scientific discipline regardless of the fact that it's consummate junk.
Even if I provide to the to a greater extent than acceptable notion of "history earlier the Big Bang", I retrieve that the room for whatever meaningful physics of that form is extremely limited. In other words, I am almost sure that all these ideas must hold upward wrong. There's ever a work with the entropy earlier the Big Bang that should hold upward fifty-fifty lower than the entropy at the minute of the Big Bang – as well as the latter is rather depression if non zero. (Cyclic universes run across a conflict with the 2nd police clit of thermodynamics, too.)
And so there's a work with whatever predictive consequences of the pre-Big-Bang stage. One argue is that during the Big Bang, the spacetime curved shape is huge, perhaps Planckian. That way that all gadgets – including all standard apparatuses – pause there. Because physical quantities are exclusively meaningful to the extent to which they're measurable yesteryear apparatuses, I retrieve it's right to enjoin that fifty-fifty the continuity or predictability of the observables during the Big Bang era disappears. If all clocks pause etc., the fourth dimension itself becomes meaningless inwards the vicinity of the Big Bang, as well as that's why yous shouldn't enquire how the post-Big-Bang fourth dimension is connected to some other branch of time. It's a physically meaningless question.
Influenza A virus subtype H5N1 related fact is that the events are inwards the authorities of "extreme quantum gravity" or "string theory" inwards the vicinity of the Big Bang. Quantum coherence as well as phases of the amplitudes affair a lot. It seems that all the people are imagining some unproblematic marriage ceremony of classical geometries. That's almost sure enough an inadequate description inwards that extreme epoch, inwards 1 manner or another.
Stephen Hawking as well as Jim Hartle receive got proposed a much to a greater extent than promising betoken to address the initial atmospheric condition of the whole universe: their Hartle-Hawking state, the (especially initial) moving ridge component of the universe. Whatever happens inwards the really early on moments of the universe and/or "before that moment" should hold upward incorporated inwards a solid set down that may hold upward defined a piffling fighting subsequently the Big Bang when the solid set down of the basis is no longer "insanely curved" as well as otherwise problematic.
I retrieve that fifty-fifty if our Big Bang were precisely an lawsuit inwards some longer sequence of events inside eternal inflation or something similar that, at that spot should be a calculation of the probabilities that are relevant for our universe that only "integrates out" all the conceivable pre-history. The Feynman path integral has the dainty belongings that yous may acquire the resulting probability amplitudes directly, through an explicit formula.
It exclusively makes feel to beak well-nigh a "history inwards time" if the "time" is an uncontroversial continuation of the fourth dimension that nosotros genuinely discovery inwards our world. If at that spot is whatever other data or quantum data affecting us, that data as well as its impact on us should hold upward converted to the variables that are compatible with the being of fourth dimension or spacetime of our type. In particular, all pre-Big-Bang influences should hold upward convertible to a Hartle-Hawking solid set down at the commencement of our fourth dimension right subsequently the Big Bang.
I retrieve it's almost rigorously provable that no other handling of the hypothetical pre-Big-Bang development of the universe may receive got defensible as well as calculable consequences for our post-Big-Bang evolution. But fifty-fifty if yous incertitude this ambitious arguing of mine, it's a fact that no convincing explanation of whatever observable fact well-nigh the universe using a pre-Big-Bang (or cyclic) concepts has been proposed inwards the literature so far.
No comments:
Post a Comment