I totally hateful it: Inflation never solved the flatness problem.I would personally never allow a pupil to teach a marking from theoretical physics or something similar that if she were a quack similar her who just doesn't teach the most key ideas inwards the acre – together with she doesn't. But in that location are goodness reasons why she tin "totally hateful it". Quacks similar her may practice good because spell her total scientific incompetence is a minus from the viewpoint of the actual experts, it's a addition from the viewpoint of the bad people "around" science.
For example, George Soros just gave $18 billion (80% of his wealth) to his "charities". You tin live certain that a component subdivision of this coin volition live used to assault science, just similar it was used inwards recent years. Obnoxious antiscientific whores aren't that bad, are they? In fact, they are good, discriminated against yesteryear the evil white manful somebody scientists, together with then why don't nosotros plough statements similar "inflation never solved the flatness problem" inwards a virtue that should live rewarded?
Just elbow grease to appreciate how much evil may live done amongst $18 billion that is sent to carefully, ideologically picked corners.
The whole organisation underlying scientific discipline together with other meritocratic human activities – at to the lowest degree those whose importance isn't "immediately" impacting the well-being of the ordinary Joe – is collapsing equally the people allow scum similar George Soros to create "compensating" anti-meritocratic structures that switch the development into the reverse: What sucks gets to the top.
Cosmic inflation is also almost the "reversal of the dynamics" together with that's why it's unquestionable for an skillful – or an intelligent pupil inwards fields related to cosmology – that it must live considered a vital component subdivision of our electrical current agreement of the history of the Universe.
I convey explained why inflation solves – together with is basically needed to solve – the flatness occupation e.g. inwards my article celebrating Alan Guth or an answer at Physics Stack Exchange. Hossenfelder mixes inflation together with initial weather inwards weird together with illogical ways.
But the cosmic inflation actually is needed together with it is needed to ready feasible initial weather for the subsequent development according to the equations of the big bang theory. How does it work?
General relativity allows yous to derive that inwards a uniform, isotropic Universe, the apartment \(\RR^3\) slices may last inwards time, during the expansion, if the affair density is "critical". So the affair density divided yesteryear to a greater extent than or less business office of Hubble's constant etc. is called \(\Omega\) together with \(\Omega=1\) way that the Universe is apartment at a given 2nd together with stays apartment despite the expansion.
But it's never exactly apartment together with nosotros may written report how \(\Omega-1\) evolves amongst time. Pretty much yesteryear the Definition of \(\Omega\) I mentioned, nosotros may know that\[
\Omega-1=\frac{k}{a^2H^2}-\frac{\Lambda}{3H^2}
\] And yesteryear Einstein's equations, nosotros may written report how \(|\Omega-1|\) increases or decreases amongst time. We uncovering out that today, inwards the "normal" big bang expansion, it increases amongst time. The Universe is getting less flat equally it gets older. Because it's yet rather apartment today, \(|\Omega-1|\leq 0.01\) or so, nosotros may come across that it was extremely apartment seconds afterwards the big bang, maybe with\[
|\Omega-1| \approx 10^{-{\rm dozens}}
\] If yous dig deeper together with written report increasingly early on moments of our Universe, yous volition come across – just because of Einstein's equations – that the Universe was increasingly unnaturally flat, together with it was almost just apartment at each corner. It way that our big bang theory entirely industrial plant is yous supplement it amongst initial conditions that must live especial – they must honour the extremely precise flatness at each indicate of the Universe.
Now, yous should pick your initial weather and/or logic to approximate whether ane alternative of them is probable or not. But because the value of \(|\Omega-1|\) has to live this unnaturally tiny, together with it must agree independently at each of the zillions of places of the Universe, the unremarkably calculated probability according to whatsoever sensible framework volition live something like\[
10^{-{\rm dozens} \times N}
\] where \(N\) is the publish of "independent" regions of the Universe that yous demand – yous needed to impose the unlikely flatness for each of them. The probability is hence insanely low. When to a greater extent than or less probability is this low, yous could exercise it to disprove the theory – disprove the big bang theory. That's how nosotros disprove theory. H5N1 scientific hypothesis is disproved if yous tin present that it depends on events that are predicted to live immensely unlikely. An immensely unlikely supposition that is needed may live translated to a really depression probability that the hypothesis itself is right. That's how Bayesian reasoning together with scientific discipline work.
So yous should meliorate convey to a greater extent than or less extra piece of the theory that says that these very apartment initial weather aren't actually that insanely unlikely. And inflation is that extra piece – and, upward to plagiarism together with little modifications, together with upward to proposals whose success inwards achieving flatness hasn't been understood yesteryear many people (string gas cosmology), it's yet to a greater extent than oft than non considered to live the entirely known piece that tin play this role.
How does inflation solve the flatness problem? It only adds the price to the expansion coming from the "temporary cosmological constant" \(V(\phi)\), the inflaton potential, together with from the kinetic term of the inflaton, \((\dot\phi)^2\). And when the inflaton sits or moves far plenty from the minimum of \(V(\phi)\), yous volition live able to come across that in that location are novel price that create upward one's withdraw heed almost the fourth dimension development of \(|\Omega-1|\). You retrieve I wrote that \(|\Omega-1|\) is increasing amongst fourth dimension today? OK, together with then inflation only adds novel price that contrary the overall evolution. As the Universe is getting older, \(|\Omega-1|\) is getting smaller during inflation – the Universe is getting flatter. It's doing together with then everywhere where the corresponding status for the inflaton, basically \(V(\phi)\gt (\dot\phi)^2 \), is obeyed.
So from Einstein's equations applied to the good tested ordinary big bang expansion, nosotros know that a 2nd afterwards the beginning, the Universe was extremely apartment – fifty-fifty flatter than today, yesteryear the smallness of \(|\Omega-1|\). Why was it together with then flat? Because in that location was a previous era that made it flat. It made it almost just apartment yesteryear a machinery that is pretty much equally uncomplicated together with straightforward equally the machinery that makes it less apartment today. There is just a novel term amongst the opposite sign.
To to a greater extent than or less extent, to a greater extent than or less inflation or its "generalization" had to live in that location because nosotros almost direct detect it. It's similar a hot soup. The soup is besides hot together with then you're waiting when it gets colder together with then that yous don't forcefulness out your oral cavity when yous swallow it. While you're waiting, yous may inquire why it was together with then hot to start with? Well, yous correctly guess, it's in all probability because someone heated it up. Some create or heater or somebody similar that. It's exactly the same amongst the flatness. We come across that the flatness goes downwardly – becomes less perfect (like cooling soup). Why was it together with then immensely apartment (hot soup) inwards the past? Because in that location was a previous procedure that just made it flat.
What's together with then impenetrable almost these basic ideas that people pretending to deserve their physics PhDs brag that "they actually hateful it" that this explanation doesn't move inwards to a greater extent than or less weird way? How it could not work? Her text together with her championship is exactly equally indefensible equally a comment of a visitor of the restaurant:
I totally hateful it: heaters together with ovens convey never actually solved the occupation why the nutrient got hot earlier the waitress brought us the food!Oh, really? So what's the explanation that the soup was hot? Why would a sane together with honest somebody deny fifty-fifty the really little fact that nosotros convey quite to a greater extent than or less evidence that to a greater extent than or less machinery has heated the soup earlier the waiter brought it to us?
You know, almost everyone who has at to the lowest degree "some" credentials inwards cosmology knows that Guth, Linde, together with pals – together with interpreters of those discoveries such equally your humble correspondent – are right spell Hossenfelder is just totally wrong. The evidence is totally on our side together with the likes of Hossenfelder are demonstrably wrong. But inwards our intellectually deteriorating society, this fact is becoming increasingly irrelevant. The likes of Hossenfelder convey been edifice a whole network of alternative institutions of mistaken science, ane that has almost completely merged amongst the Soros-style network together with the PC media.
I think that the missive of the alphabet of the tiptop inflation researchers symbolized this immense gap. Pretty much everyone who has done something of import inwards that acre or related fields understands the instance for inflation, the depth of the inflationary ideas, together with their unmatched mightiness to explicate the foreign together with seemingly unlikely features of the initial weather that the normal big bang expansion requires. But yous could come across that all these tiptop physicists together with Nobel prize winners etc. didn't look to brand almost whatsoever deport upon on the broader "community" of the writers almost scientific discipline together with materials similar that. An abyss has been growing for decades – together with the tiptop scientists' determination to avoid nontrivial interactions amongst the media has helped the growth. It's fourth dimension to realize that this abyss is existent together with has croak unsafe for the really survival of science.