Hacker News Reader

Comment by p4bl0 | Hacker News Reader

EDIT: Sorry I came back from the article to say this before reading the comments here… I should have, the top comment is already saying the exact same thing!

The speed of light isn't that fast. The website "the moon is one pixel" is a webpage where our solar system is represented at scale if our moon were 1px in diameter : https://joshworth.com/dev/pixelspace/pixelspace_solarsystem....

You can scroll through it. It's so long to go from one planet to another. So much empty space.

At some point you're tempted to click on the C button which you see on the bottom right of the page. Speed of light! Surely that will autoscroll fast! … Nope, to scale, the speed of light is waaaay slower than your scrolling was! And then you realize, at the size of the universe, how even light isn't that fast.

View on HN

If I had to write a “game of life” simulation that simultaneously calculated the effects of all events at each point in a 3D matrix over time, I would:

- make the matrix as rough as possible while still enabling interesting events (ie, try and maximize the Planck length)

- make the maximum speed at which events propagate across the matrix as slow as possible to save the CPU (ie, try to minimize the speed of light)

- limit the size of the simulated universe

But our Planck length is tiny and the universe is probably humonguous unless we’re being deliberately deceived by This Simulators.

So despite the suspicions aroused by the slow speed of light, we might live in the mother / “real” universe after all.

I think you might have the same misconception about the planck length that I had:

"The Planck length does not have any precise physical significance, and it is a common misconception that it is the inherent “pixel size” or smallest possible length of the universe.[1] If a length smaller than this is used in any measurement, then it has a chance of being wrong due to quantum uncertainty.[2]"

https://simple.m.wikipedia.org/wiki/Planck_length#:~:text=Th....

I think that sentence as written is itself based on a misconception. The idea is not that the Planck length is physically meaningful, but rather that that quantum uncertainty is caused by the structure of the universe (discrete spacetime). In other words, that uncertainty is analogous to aliasing in a signal.

>make the maximum speed at which events propagate across the matrix as slow as possible to save the CPU

How would that save CPU time?

The Game of Life does have a maximum speed of propagation of causality, but it's not designed in, it's just a consequence of the basic rules that define the simulation.

Well, you could just slow down the execution rate of the whole simulation.

But if you limit the speed at which events propagate, my feeling is the rate of events occurring will be lower overall, since one event triggers another and each event will trigger fewer secondary events per second if it propagates less distance per second.

You could now also have islands of stability so that a cataclysm on one end of the simulation will take a long time to spread to the rest of it.

IE, Andromeda can explode and we won't even know for a long time. In that time, we will continue doing interesting / entertaining things, or continue calculating the answer to life, the universe, and everything.

If the propagation of effects is slowed down, the phenomena that you are interested in will take more simulation steps to complete.

I don’t know, I think the most interesting things are happening slowly and with high complexity in places like here on Earth.

With a slower speed of light, I think you’ll get qualitatively different events, not just fewer events.

But you will get fewer per step, which is my point. If you get fewer, then you'll need to run the simulation for longer, thus negating any savings.

But you're right in that you'd get different effects, because effects like gravity depend on the distance between objects, which is invariant on the speed of light, so a "human" in a universe where c is halved but everything else is the same wouldn't just be larger, but be completely different.

But if you're changing the behavior of the simulation then it's not even an optimization anymore. You just changed the simulation. It may as well be something entirely different.

Reply on news.ycombinator.com