Ask HN: Assume the universe is a simulation. Why is c the speed of light? | Hacker News Reader

Ask HN: Assume the universe is a simulation. Why is c the speed of light?

20 pointsvinaybn25 comments

Is it the processor's clock-speed, always constant?

Why a technical reason? Maybe it's a deliberate design decision, like how the physics are set up in a video game. Maybe in this sort of scenario, they did some playtesting and found that setting light to that speed made the game more 'enjoyable'.

Then again, it could be a way to cover up for a lack of content. Set the speed of light to be faster, and it might theoretically make it so a species with massively advanced technology could reach the edge of the universe. More convenient and realistic than an invisible wall.

A connection between the simulated universe's speed of light and its host CPU's clock speed would imply real-time simulation. I see no reason why that would necessarily be the case for a simulated universe; most research-grade physics simulations humans run today aren't real-time. (They would be real-time or faster if we had the hardware to run them that way — I imagine a sufficiently accurate physics "REPL" would help a researcher tremendously — but we make do without them.)

This doesn't make sense to me. Assuming this is a simulation, real-time isn't "real" time.

By "real-time" above I mean from the perspective of whoever runs the simulation. Compare: https://en.wikipedia.org/wiki/Real-time_simulation.

The puzzlement consists of using "universe" in two incompatible contexts without paying clear attention to the distinction between the contexts.

The first context is the ordinary one in which the universe is roughly the container for everything that is including ourselves.

The other context is one in which the universe is a simulation of a container for everything that is including ourselves that is indistinguishable by us from an actual container for everything that is including ourselves.

It's fine to use the latter definition, so long as one recognizes that the use is very odd and problematic and any conclusions one draws while using it are simulated conclusions about the simulated container and not conclusions about the actual container for everything that is including ourselves. To put it another way, if the universe is a simulation then "light" and "speed" and "C" refer to elements of the simulation and need not have a one to one correspondence to entities in the actual universe. Human knowledge can only be knowledge of the simulation.

Our knowledge is limited to things it is possible for humans to know. If we're in a simulated universe, then we can only know about the simulation.

I have a similar view, but at the same time I still have a little bit of hope that even if the universe was a simulation, there would be some way to somehow go outside the simulation (e.g: by 'thinking', if that would make sense, about outside-the-simulation concepts; something like escaping the VM). But it's kind of an emotional reaction to the realization of the limits of one's mind/perception ;).

The question is too simplistic, because, within the simulation, the speed of light appears constant in different reference frames that move relative to one another. The simulation doesn't favor any particular reference frame; it's a supervisor over all possible reference frames, so to speak.

Perhaps the Universe is simulated by a distributed computing system. The speed of light could ensure that state remains consistent throughout the system without requiring synchronization of all of the nodes. Only spatially adjacent nodes need to communicate with each other and the speed of light could be tuned such that the bandwidth limit between the nodes would be never be reached.

If the universe is a simulation, it would have to be on an analog computer which doesn't have a clock speed as such. Or a digital computer running sufficiently tiny time steps to be indistinguishable from an analog computer. In either case I don't think c is directly related to "clock speed". I'm not a good enough physicist to tell you what it does mean. That's my feeling anyway.

I would be inclined towards digital due to the presence of Planck length and Planck time.

It's the refresh rate of "their" displays.

Actually the speed of light is just a constant that interconnects spatial and time coordinates.

In special relativity everything moves with c light speed in a 4-dimentional pseudo-Euclidian space. It means that the light speed constant c is just a measure unit that interconnects time and spatial coordinates. And the actual spatial velocity of a particle is just a projection on the spatial coordinates of it's 4-dimentional velocity which always has length equal to c.

So the existence of light speed constant seems more like a boundary condition that limits class of possible solutions rather than something connected with the processor's clock-speed.

It is my understanding that when determining the official figure,the General Conference on Weights and Measurements took an average of some of the most accurate measurements that were available at the time. But I think that there were variations in each case. So we could assume that either our tools were just not precise enough, or that the speed of light is not actually constant. (or both?) I'm curious, are physicists these days routinely measuring the speed of light, and if so are these measurements consistent?

It is the fixed rate at which all mass-energy is moving through space-time. The rate never changes for anything. If an object is moving slowly through the space axis of space-time then it is moving quite rapidly, though at a fixed and predictable rate, through the time axis, and vice versa. C is the rate at which time and space are flowing in the simulation. Clock speed is a good analogy.

Could just be a bug between time and space being linked while it should not.

Or we need to buy the FTL DLC

What video game doesn't have constants?

  const LIGHTSPEED = 299_792_458

How many significant figures does it need to have, do you think?

And that makes me wonder, how does this simulation deal with irrational numbers and real numbers? How does it represent pi and radical 2? The Greeks were afraid of these numbers. Are they are problem for a theory that we are a simulation run on finite resources?

I think it has to do with the concept of computable vs non computable functions. One stand is that if the Universe is a simulation then by definition it is computable but we can clearly define and reason about non computable things (which suggests that it is not in fact just a Turing machine and may in fact the hyper computer running the simulator. But you can't really get above that. So the speed of light is just a defined constant which no meaning and we can't pierce the through hypervisor.

https://en.wikipedia.org/wiki/Simulated_reality#Computationa...

Without knowing physics, maybe we should find a good simulator, change the speed of light constant and see how the interactions change.

Alternatively, see if different equations scale differently based on the speed of light.

c is the speed of light because then you can create a constraint over the size of the universe, also make everything that is placed inside of this universe that has mass locked inside it, as it would take infinite energy to get something with mass(which also would go to infinite) to be at the same speed of light.

Because that value made life, as we know it, possible.

Hardware limitation?

In order for any simulation to proceed at a steady state, there must be at least one constant. Everything else can be variable, but in order for time to progress at the same "tick", it has to have something to measure by.

That said, why create a "tick" when the perception of that tick can vary by individual? When I go into code mode, 10 hours can slip by in an instant, and I'm not hungry or thirsty until I come out of it.

Perhaps it's just an affectation of focus, as time still "ticked" by at it's normal rate.

Einstein said that the effects of time move more slowly the closer you get to C, so it makes sense that C would be the univeral "tick" if this was a simulation. As evidenced by Mars rovers and Voyager, an earth clock on another planet or in space still ticks at the same rate (Voyager and Mars are moving through space at the same rate we are moving around the sun, about 61,000km/hour).

There's no other reason for light to move at a steady speed, and nothing apparent that's stopping it from going faster.

The most interesting thing about what you said is you don't need coffee every 10 minutes in code mode.

This "tick" theory gets my vote.

I see c as an emergent quality of a base granularity. If the universe is a cellular automata then c would be related to the distance between two successive layers, between what just happened and what is happening now, between now and next.

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