In the video AronRa, discusses the origin of the universe and just about everything he states in the video is either demonstrably false or it’s simply made up for sensationalist or ideological purposes. Normally I wouldn’t care, there are plenty of sources on the internet written by people who misrepresent fields of science they don’t understand but when it’s made by people with a popular following and who give their audience the impression that they know what they're talking about, usually with technical language (a lot of which he himself doesn't understand), it's all together different.
I'm not interested in any of the theological statements or any of the over-the-top anti-religious sentiments in the video. I want to go through some of the claims related to physics.
In the video AronRa equivocates between "expansion" and "inflation" as if they were the same thing. Inflation was first proposed by Starobinksy and Guth in the late ‘70s to solve the flatness and horizon problems of the standard Big Bang model. A year later, Andrei Linde suggested it would the monopole problem, but it was understood as an add-on to the Big Bang theory.
I'm not interested in any of the theological statements or any of the over-the-top anti-religious sentiments in the video. I want to go through some of the claims related to physics.
In the video AronRa equivocates between "expansion" and "inflation" as if they were the same thing. Inflation was first proposed by Starobinksy and Guth in the late ‘70s to solve the flatness and horizon problems of the standard Big Bang model. A year later, Andrei Linde suggested it would the monopole problem, but it was understood as an add-on to the Big Bang theory.
AronRa appears to think that inflation is a part of the standard Big Bang model. It's not, a universe inflates when $\ddot{a}\left ( t \right )> 0$ Where a is the scale factor of the universe. It wasn't discovered along side the red shift of galaxies, the abundance of deuterium and other such elements, or the Cosmic Microwave Background. Inflation is altogether a different proposal to the expanding universe which is described by the first Friedman equation:
Without adding a cosmological constant, the second derivative of the scale factor does not need to be non-zero. Nothing in Friedman's equation or standard Big Bang cosmology suggests that the rate of expansion is positive, in fact the second Friedman equation tells us that the universe's expansion is slowing down.
In the same video, we're told that time had a beginning but "physicists aren't really certain" on whether or not the universe had a singularity (this occurs around the 3:50 mark). Partly, this confusion arises because of a false equivalence between the Big Bang theory and the standard Big Bang model. In the standard Big Bang model there is an initial singularity and a beginning of time but neither of these are predictions of the Big Bang theory.
A spacetime singularity is a boundary in a mathematical model where past-geodesics terminate in the early universe under the effects of gravity, because of this the "metric" equation in general relativity breaks down and it no longer makes sense to talk about a time "before" the Big Bang. As found in every introductory textbook to astrophysics or astronomy, a singularity would mean an absolute beginning to the universe.
AronRa disagrees, (at around 6:23) he argues that "one second stretches out to infinity when $t = 0$" and that "energy was literally always here". It's difficult to understand what this means or where he got this from because it wasn't something any cosmologist said, he's simply made it up. What it means to say "time had a beginning" is simply that the universe began to exist, there was an earliest time $t = 0$ "before" which there was no universe.
There's another problem in this argument, in classical mechanics, the term "energy" denotes the "ability to do work" like the capacity a system has to produce heat but AronRa seems to think that energy is some kind of substance like matter. I wonder if AronRa passed his High school physics course, earlier in the video (at around 5:48) he uses phrases like "matter and energy" when he obviously means "mass and energy" not realising what the definition of mass is either, in physics. Or phrases like "boundary" when he clearly means a universe without a boundary, i.e. a singularity.
Singularities appear in the second Friedman equation because there is no upper bound on the density or pressure of the early universe according to general relativity. However, almost every cosmologist believes that this argument unfairly assumes general relativity dominates where quantum gravity becomes important. Proposals for a possible theory of quantum gravity like Loop Quantum Gravity, String theory, Closed Dynamic Triangulation etc. involve a minimum volume of space or matter which prevents a singularity from forming.
Of course, the Big Bang theory is compatible with all of these proposals. Earlier still, (at around 5:00) there's another gargantuan problem. When AronRa talks about "the impossibility of an absolute philosophical nothing" with regard to a quantum vacuum his argument is obviously fallacious, it's true that a vacuum cannot be absolutely empty and we know this because the electric and magnetic fields form a Hesienberg pair but the vacuum is subject to singularity theorems. It does not somehow exist apart from or independently of spacetime.
In fact this conclusion was proven famously in general relativity by Penrose-Hawking, then independently of Einstein's gravitational equations by Arvind Borde, Alan Guth and Alexander Vilenkin and then in quantum field theory in curved spacetime by Aron Wall.
Another part of the video also confused me (at around 6:46) when AronRa talks about the possibility that entropy decreased before the Big Bang. Entropy is the logarithm of the total number of ways a systems atoms can be arranged $S = kLOG\left ( W \right )$ it increases on average because there are far more disordered states than ordered states that a system can be in. There are models in cosmology which reverse the arrow of time (e.g. Carroll-Chen, Aguirre-Gratton, Hartle-Hertog and others) but entropy does not "decrease". It increases in a different direction. Only a scenario in which all energy becomes heat, and entropy is already maxed out would the second law disappear. I got rather tired at this point but thankfully he stopped talking about physics.
AronRa, if there's any chance that you're reading this and made it this far, somehow managing to find the time out of your day, from telling us how ignorant and stupid you think religious people are, perhaps you should study up on physics. Your understanding is it's fair to say, behind.
Sincerely,
Andrew Wells
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ReplyDeleteI want to put one question:
ReplyDeleteWhat was the value of space, time, matter and energy at the beginning of the universe and what are their present value?
10^69 joules
Delete