### Simulation Argument

Sometimes when certain ideas are trending the scientific press, it's well deserved, a lot of the time it's not. I imagine by now most people have probably heard of the Simulation Argument, it comes from a 2003 paper by the philosopher Nick Bostrom. Essentially it's a statistical argument to the affect, that we're very likely living in a simulated universe rather than a real one. The argument goes something like this:

1. It's possible to simulate a universe like ours, with the kinds of experience we have in this world.

2. Perhaps far in the future, the technology to do so will exist and become sufficiently wide spread.

3. Future beings will be interested in running ancestor simulations of their past.

4. If 1-3 are true, then in the entire history of the universe simulated worlds will vastly out number real ones.

We should assume we’re typical observers and so therefore we are likely living in a simulated world rather than a real one. A lot of people like the idea that the universe is a simulation, they may think it speaks to their mental flexibility but actually it portrays a fairly weak grasp of physics. The argument was covered on Sean Carroll's blog and he has a pretty good objection to it.

One way to understand this picture of the world is in terms of "digital physics" that all of reality, the laws of nature, spacetime, matter, energy are at bottom made up of grid nodes of bits, and encoded on an algorithm; looking at it top-down, gravity is the curvature of spacetime, so a quantum theory of gravity entails that spacetime is made up of discretely quantized parts.

That's a very naive approach to quantum gravity, and today we know a lot better. If we try to build up spacetime from 'atomic-like chunks' then our theory is not going to be Lorentz invariant–that's fancy sounding science jargon for "in conflict with known physics" namely special relativity–if with respect to one reference frame I cannot talk about time separations smaller than a certain duration, then I can have a second frame of reference moving very fast with respect to first where those separations become enormously large. Where violations in the principle of relativity will be observed.

Second, if spacetime is built up from Planck sized units of volume, I should be able to do a very rudimentary calculation to infer the total number of bits of information I need to specify for a complete picture of that given region of spacetime. It should be:

$S = \frac{V}{P_{v}}$

The problem here is that, that's false. We have a better way to calculate the information encoded in a region of space, using the Holographic Principle. The degrees of freedom are limited by the area of the boundary of a given region of spacetime, so S is proportional to the area, not the volume of that region.

Certain features of our world–spacetime, potentially consciousness and in my view, God–cannot be simulated on a computer, that already makes the Simulation Hypothesis impossible to accept.

I wish science popularizes (or the science media) would stop promoting the simulation hypothesis as though it were serious science, it's not even close to being half of a scientific idea. Digital physics hasn't derived General Relativity or the Standard Model of Particle physics, and there are seriously questionable philosophical assumptions fed into the argument as well.

It neglects for example that the physical substrate for consciousness is a biological organ, not an algorithmic code. Bostrom assumes "substrate independence" but the fact that I can simulate something looking very similar to rain on a computer doesn't mean that the computer program is itself wet, inside. Even if you could simulate a conscious being neuron-by-neuron, it would be at least as complex as the brain itself. Each person can't be "copied and pasted" but is an individual, which makes it incredulous at best, to imagine that simulated people will hugely out number real people.

The simulation argument isn't something that keeps me up at night, most people who read about these ideas in the scientific press are probably going to conclude that these "science" authors are full of shit and I don't blame them.

### William Lane Craig and the Hartle-Hawking No Boundary Proposal

Classical standard hot Big Bang cosmology represents the universe as beginning from a singular dense point, with no prior description or explanation of classical spacetime. Quantum cosmology is different in that it replaces the initial singularity with a description in accord with some law the "quantum mechanical wave function of the universe", different approaches to quantum cosmology differ in their appeal either to describe the origin of the material content of the universe e.g., Tyron 1973, Linde 1983a, Krauss 2012 or the origin of spacetime itself e.g., Vilenkin 1982, Linde 1983b, Hartle-Hawking 1983, Vilenkin 1984.

These last few proposals by Vilenkin, Hartle-Hawking and others are solutions to the Wheeler-DeWitt equation and exist in a category of proposals called "quantum gravity cosmologies" which make cosmic applications of an approach to quantum gravity called "closed dynamic triangulation" or CDT (also known as Euclidean quantum gravity). I&#…

### How Should Thatcherites Remember the '80s?

Every now and again, when I talk to people about the '80s I'm told that it was a time of unhinged selfishness, that somehow or other we learned the price of everything but the value of nothing. I can just remember that infamous line from Billy Elliot; 'Merry Christmas Maggie Thatcher. We all celebrate today because its one day closer to your death'. If it reflected the general mood of the time, one might wonder how it is she won, not one but three elections.

In an era when a woman couldn't be Prime Minister and a working-class radical would never lead the Conservative party, Thatcher was both and her launch into power was almost accidental owing in part to Manchester liberals and the Winter of Discontent. Yet I'm convinced her election victory in '79 was the only one that ever truly mattered. Simply consider the calamity of what preceded it, the 1970s was a decade of double-digit inflation, power cuts, mass strikes, price and income controls, and the three…

### Creation Of Universes from Nothing

The above paper "Creation of Universes from Nothing" was published in 1982, which was subsequently followed up in 1984 by a paper titled "Quantum Creation of Universes". I decided it would be a good idea to talk about these proposals, since last time I talked about the Hartle-Hawking model which was, as it turns out, inspired by the above work.
Alexander Vilenkin also explains in a non-technical way the essential idea in his book; Many World's in One – one of the best books I've ever read – it mostly covers cosmic inflationary theory but the 17th chapter covers how inflation may have begun. In fact Vilenkin is one of the main preponderant who helped develop inflation along with Steinhardt, Guth, Hawking, Starobinsky, Linde and others.
Although I won't talk about it here, Vilenkin also discovered a way of doing cosmology by using something called "topological defects" and he has been known for work he's done on cosmic strings, too.
In ex…