http://theconversation.edu.au/alert-you-may-be-living-in-a-simulated-universe-10671
Be Well.
David
Alert: you may be living in a simulated universe
As a cosmologist, I often carry
around a universe or two in my pocket. Not entire, infinitely large universes,
but maybe a few billion light years or so across. Enough to be interesting. Of
course, these are not “real” universes; rather they are universes I have
simulated on a computer. The
basic idea…
Author
Disclosure Statement
Geraint Lewis receives funding
from the Australian Research Council, including a Future Fellowship.
The Conversation provides
independent analysis and commentary from academics and researchers.
We are funded by CSIRO, Melbourne, Monash, RMIT,
UTS, UWA, Canberra, CDU, Deakin, Flinders, Griffith, La Trobe, Murdoch, QUT,
Swinburne, UniSA, UTAS, UWS and VU.
Articles by This Author
Everything we see around us could
be little more than bits in a giant supercomputer. petertandlund
As a cosmologist, I often carry
around a universe or two in my pocket. Not entire, infinitely large universes,
but maybe a few billion light years or so across. Enough to be interesting.
Of course, these are not “real”
universes; rather they are universes I have simulated on a computer.
The basic idea of simulating a
universe is quite simple. You need “initial conditions” which, for me, is the
state of the universe just after the Big Bang.
To this, you add the laws of
physics, such as: how gravity pulls on mass, how gas flows into galaxies, and
how stars are born, live and die.
You press “go”, and then sit back
as the computer calculates all of the complex interactions, and evolves the
universe over cosmic time. The video below gives a good introduction:
A wonderful description by Andrew
Pontzen on how astronomers synthesize and study their very own galaxies and
universes.
What’s more fun is playing
“Master of the Universe”, and messing about with the laws of physics, such as
changing the properties of gravity, or how black holes swallow matter. Waiting
to see the outcome of these mutated universes is always interesting.
I know in my heart that these
universes are nothing more than ones and zeros buried within my computer, but
in the movies I make of my evolving galaxies and clusters, and the one embedded
further down in this article, I can see the mass moving around. It looks real!
Computer simulations of complex
phenomena are everywhere in science, and cosmologists aren’t the only ones that
marvel at synthetic chunks of the real universe.
It is equally inspiring to watch
the flow of air around a newly-designed wing (see video below), or how individual molecules make their way through a
biological membrane, and such simulations have revolutionised science.
Of course, these advances have
only occurred with the growth of computer power over the last few decades, and
the push is always towards the inclusion of more complex physics over an
immense range of scales, from the cosmological to
the quantum.
We are always limited by the
power of computing, but as computers get bigger and faster, so does the detail
within our synthetic universes.
“Cosmologists aren’t the only
ones that marvel at synthetic chunks of the real universe.”
But let’s imagine a time in the
future, a time when computers are powerful enough to fully simulate a human brain,
with its vast array of interconnected neurons.
These neurons obey the laws of
physics, and fire as their chemical balances change. Thoughts would echo around
this synthetic brain, with electrical signals coursing backwards and forwards.
Not being a philosopher, I will
ignore the (seemingly endless) debates about free will and consciousness, but
if you take a purely mechanical view of the human brain, the synthetic brain
will be as “alive” as the organic brain that made it.
Fed with the stimulus from a
synthetic body interacting with a synthetic universe, it will experience pain
and fear, happiness and love, even boredom and drowsiness.
There are, in fact, some that believe we
will all be reborn in a glorious future, where computers are powerful enough to
recreate everyone who has ever lived, and then sustain them for eternity.
While this vision of heaven is
touted as the Final Anthropic Principle,
some have more bluntly labelled it the “Completely Ridiculous Anthropic
Principle”, or C.R.A.P. for short.
But we may not have to wait until
the distant future!
“In simulations, I can see the
mass moving around. It looks real!”
To quote the
late, great Douglas Adams, “there is another theory which states that this has
already happened”.
Not that someone on Earth, or
even within our universe, has created a truly synthetic universe, complete with
beings that are clueless to the fact they are nothing but part of a computer
experiment.
No, the startling realisation is
that we, our very existence, every thing we have seen, have experienced, or
will ever experience, could be nothing but the chugging of bits in an
unimaginable supercomputer.
As I type this on a laptop, and
stare out the train window at the station rolling past, at the people, the
trees, the dirt on the ground, surely I would know if I was part of a computer
program?
But then again, my brain is
simply processing inputs, and if the simulated inputs fed into my simulated
brain are good enough, how would I know?
It is important to remember that
this picture is different to the “Brain-in-a-vat”
presented in the Matrix movies. There, an organic brain is fed information,
recreating the synthetic world in which the characters find themselves.
Instead, our picture is that
there is no organic brain. We are part of the matrix itself.
So, how can we know if we are
part of a computer simulation?
It is important to remember our
earthly computers are limited in the way they can represent real numbers,
holding only a finite number of digits for typical calculations.
What this means is that my
simulated universes are quantised in some sense, with the limited resolution
imprinted in the details of the structure that is produced.
If we are living in a computer
simulation, then maybe such resolution effects are apparent to us. Our world
doesn’t look like the Minecraft universe (see video below), and so we expect
the resolution scale to be smaller than the scale of individual atoms, rather
than large, foot-cubed blocks.
Just last month, researchers from
the University of Bonn, Germany suggested we can detect such “chunkiness” of the small scale by
looking how high-energy particles, known as cosmic rays,
traverse huge distances in the universe. As these rays bounce through this
space, their energy properties get modified, and by looking at what arrives on
Earth, we can work out the size of the chunks.
But there are problems with this
idea.
Firstly, we are working under the
assumption that the computer we live in operates like an everyday computer. But
these everyday computers are governed by the laws of physics of the synthetic
universe in which we reside.
The unimaginably powerful computer
that hosts our universe may operate in ways we cannot even think about.
5
The resolution scale of our
universe is considerably smaller than in the “chunky” Minecraft universe.
Another problem is that those
trying to understand the nature of the very small have already proposed a quantised backdrop of
space and time in which we live.
Is the existence of such a
space-time simply a property of a real universe, or the tell-tale sign of a
synthetic one? How can we ever tell them apart? Do we even want to?
One way of potentially detecting
the real nature of the universe is to search for the extraordinary – or, in the
words of my children, who play videogames, glitches – where the program
doesn’t do as expected.
Perhaps some of the unexplained
things we cannot yet explain are simply glitches in the program (although I am
a fan of illusionist Derren Brown and
think the human mind can be easily tricked).
The other alternative is more
drastic.
When my synthetic universes are
running, they can abruptly come to a halt for a variety of reasons, such as
disk-space filling up, errors in the memory, or something as simple as the
cleaner unplugging the computer to vacuum the floor.
If my synthetic universe is
running when the power goes out, it simply ceases to exist.
I do hope the cleaners of our
potential-hyperdimensional-universe-simulating overlords are more careful.
Further reading:
- The measurement that would
reveal the universe as a supercomputer simulation – Technology Review
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