Monday, December 18, 2017

Eternalism Is Not The Steady State Theory

One way I can quickly tell someone isn't educated on cosmology and physics is when they confuse eternalism with the steady state theory. When most people hear "eternalism" they think it means the universe has an infinite number of past events. They mistakingly conflate the "eternal" in eternalism with meaning infinite past. And since we know our universe doesn't have an infinite past because of the big bang theory, they'll say eternalism must therefore be false.

Case closed.

But this of course only exposes one's ignorance, because anyone who knows better knows that eternalism is a completely different model than the steady state theory. I recently had a debate with a theist who made his ignorance on the subject matter abundantly clear, and it left him thinking he was correct on cosmology and that I knew nothing about science.

So let's define a few things to make it clear what eternalism is and isn't to show that it is not the steady state theory.

The steady state theory was a view that dominated physics before the discovery of the big bang and Einstein's general relativity. According to this view the universe is in the same exact (more or less) state that it currently exists in for an infinite amount of time in the past, and will continue the exist the same way into the infinite future. If we rewound the universe back any arbitrary amount of time, say, a billion years, a trillion years, a googol years, it would look more or less the same with galaxies, stars and planets. And if we fast forwarded the same amount of time we'd see a universe that looks more or less like it does now with galaxies, stars, and planets. During that time stars would die and new ones would continue to form, and whole galaxies may go in and out of existence, but overall at the largest scales the universe would look the same as it does now into the infinite past and future. There would be no overall change to the universe at the largest scale and entropy would stay the same at all times.

Einstein famously was a steady state theorist, as were most physicists in the early 20th century, until a Belgian Monk and physicist George Lemaitre took Einstein's theory of general relativity to it's logical conclusion and showed that the universe must be either expanding or contracting. A few years after that Edwin Hubble discovered the red shifting of all the other galaxies indicating the universe was indeed exapanding. Einstein abandoned the steady state view.

But even through general relativity made it impossible to hold onto a steady state model of the universe, special and general relativity made it impossible to hold onto a Newtonian view on time being absolute. Both theories entailed eternalism, upon which the universe could be eternal, without having an eternal past.

Einstein famously was an eternalist. But it wasn't until his math teacher Herman Minkowski showed a young Einstein that his new special theory of relativity entailed a 4 dimensional block universe a few years after the the theory came out, that Einstein adopted the view we know today as the block universe, which is eternalism.

So for a while Einstein was a steady state theorist and an eternalist it seems. But the two views are very different.

Eternalism, is the philosophical name given to the 4D block universe, AKA the tenseless theory of time or the B-Theory of time. It is completely derived from physics, mostly special relativity. It says that all moments of time—past, present, and future—physically exist in a block universe, which is all of space that exists and all of time that exists. All these moments are eternal, hence the name eternalism. But eternalism says nothing about whether there are an infinite number of moments in the past. Therefore, eternalism is compatible with the big bang theory because all that is required is that the block universe have at one end of it a low entropy point that minimizes into a singularity. That is the big bang. Thus in the block universe, there isn't the same state of the universe persisting throughout it, and the universe can be eternal without having an infinite number of moments in its past.

One slice of time in the block universe will contain within that slice the existence of things that will not necessarily exist in another. For example, in the slice of time just after the big bang there is extremely low entropy, at the slice of time now there is higher entropy and glaxies will dominate the universe, and at the slice of time a googol years from now there is maximum entropy and no more galaxies.

Therefore to conflate the steady state theory with eternalism is false and an indicator of one's ignorance of physics.

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