"Speed of Light"

Is there a physics/mathmatical reason for the ultimate speed limit, (avoiding saying "speed of light"), to be what it is? Or even to exist at all?

I mean, if the speed limit was, say, 200,000 mps, or 1 billion mps, would anything happen other than calculations change and things go faster -- other than just the numbers get bigger? What if there was no speed limit -- light could move instantaneously? Would this "break" the universe?

Considering the size of the universe, it seems that this speed limit is really, really, really, ridiculously slow. Is there a scientific reason for this low limit?

Bullgrit

Bullgrit said:

Is there a physics/mathmatical reason for the ultimate speed limit, (avoiding saying "speed of light"), to be what it is?

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In a word, no. At least, not so far as we understand things at the moment.

There are a few constants (the speed of light, the charge of a single electron, and a couple other things) that "just are", as far as accepted models go. For some reason, or no reason, when the Universe came into being, these constants had these values. They could have had other values, and with other values, the universe would be dramatically different. As in "human life could not exist" different.

This brings us to the Anthropic Principle. We see the kind of universe we see because any universe we see must be consistent with the development of our sort of intelligent life.

I mean, if the speed limit was, say, 200,000 mps, or 1 billion mps, would anything happen other than calculations change and things go faster -- other than just the numbers get bigger? What if there was no speed limit -- light could move instantaneously? Would this "break" the universe?

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Whether or not it would break the Universe, if you vary it much, we break you. Specifically, we break atoms as we know them, so your physical body and the brain that supports your intelligence ceases to be possible. There might be a universe, and there might be stuff in it, but that stuff might be either a dissociated mist of subatomic particles or it all collapses into one big lump in the middle...

Also, and I have to think on this a bit, I believe that if light moved instantaneously, our concept of having causes and effects, the idea that events happen in an order, with one leading to another, goes out the window. There is no time. No history. No time-ordering. You cannot be born, live, and die, because there is no way to differentiate the moment of your birth from the moment of your death (from the moment you were conceived, or from the moment your parents met, or from the moment the Sun ignited).

Considering the size of the universe, it seems that this speed limit is really, really, really, ridiculously slow.

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Considering the size of your living room, though, the speed limit is really, really, ridiculously fast! Considering the size of atoms, it is even faster...

"Slow" and "fast" are measures only useful when considering some human goal - there's an implicit human-centric value judgement in those words. It seems slow, because you actually want to get over there, and the limit gets in your way.

Bullgrit said:

Is there a physics/mathmatical reason for the ultimate speed limit, (avoiding saying "speed of light"), to be what it is? Or even to exist at all?

I mean, if the speed limit was, say, 200,000 mps, or 1 billion mps, would anything happen other than calculations change and things go faster -- other than just the numbers get bigger? What if there was no speed limit -- light could move instantaneously? Would this "break" the universe?

Considering the size of the universe, it seems that this speed limit is really, really, really, ridiculously slow. Is there a scientific reason for this low limit?

Bullgrit

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Having just learned what you just learned, I like NOT saying "speed of light" as well in that it un-reinforces a misunderstanding of physics to us lay people.

I couldn't tell you if changing the c constant by +/- 1 or 100 would change much.

One goofy theory I just made up based on this new understanding is that if the universe is really a simulation, then, like a computer, it operates on a cycle. A loop of processing all elements.

It can only do that so fast. In computers, that upper limit is equal to the clock speed of the computer.

In the universe, what if c represents the limitation of the computer's cycles per second.

This is of course, a rough, made up analogy and I have not factored in exactly how c is tied to the simulation's clock cycle. it most certainly is not "c = GHz"

Janx said:

One goofy theory I just made up based on this new understanding is that if the universe is really a simulation, then, like a computer, it operates on a cycle. A loop of processing all elements.

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That assumes a physical infrastructure similar to our digital computers. One can concieve of other hardware that doesn't work in that matter - quantum computers, for example, don't really follow that pattern. You can make a DNA computer that also does not work on that same kind of loop. Who knows what hardware (or operating system) The Universe runs on?

Umbran said:

That assumes a physical infrastructure similar to our digital computers. One can concieve of other hardware that doesn't work in that matter - quantum computers, for example, don't really follow that pattern. You can make a DNA computer that also does not work on that same kind of loop. Who knows what hardware (or operating system) The Universe runs on?

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True enough, but there still would be an upper limit to what the hardware the universe simulation runs on that could form the basis of c being the constant value that it is

DNA can only compute/transfer data at a certain speed.

quantum computer thingies can only define so many states, transition to another state at a certain speed, or transfer data at a certain speed. these form constraints and bottlenecks.

Also wouldn't be so sure about loops going away. Obviously, extra-universal computers could be completely different, but the "problem" being solved remains the same.

Fewer computing resources than total processes/objects being simulated means task swapping between processes/objects in a loop/cycle.

That could be avoided if effectively every atom (or the quantum equivalent) had a CPU doing the processing on its behalf for its state managment, etc (APU?). Thus forming a neural network of all the matter in the universe in the extra-verse running the simulation.

Beats me. Though quite informed on Computer Science, I have not heard much on how a quantum computer is projected to work, in order to appreciate the differences in approach it might engender.

I do envision that programmers are going to approach it the same way as existing computers for longer than they fully embrace an alternative possibility. The same as multi-threaded development isn't something most developers embrace wholly. Instead, it gets used as needed, and many situations don't require it.

Janx said:

I do envision that programmers are going to approach it the same way as existing computers...

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In another thread, we were talking about being unable to really understand the motivations and ways of alien species.

Now, we are not only talking about aliens from another planet. We are talking about aliens from another *universe*. Not just creatures who developed on a different world that follows the same physical laws, but that could be operating under completely different laws.

I would hesitate to assert that their methods of computing* follows how we would go about it.

*If that is what we are experiencing. On the other hand, the "simulation" that is our universe might just be part of the digestive process of a hyper-dimensional being - our experience may be a by-product of a much larger process, for what meaning "larger" has in this context.

My understanding is that substantial changes to 'c' would have a dramatic impact on the nature of the universe. That is, it would break the universe, as we know it.

The nearest explorations of this sort of issue that come to mind are:

Orthogonal, by Greg Egan:

http://en.wikipedia.org/wiki/Orthogonal_(novel)

Technically, the space-time of the universe portrayed in the novels has a positive-definite Riemannian metric, rather than a Pseudo-Riemannian metric, which is the kind that describes our own univere.

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And:

Raft, by Stephen Baxter, in the Xeelee sequence:

http://en.wikipedia.org/wiki/Raft_(novel)

The novel is an elaborated version of his 1989 short story of the same title, Raft. The story follows a group of humans who have accidentally entered an alternate universe where the gravitational force is far stronger than our own, a "billion" times as strong.

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Note: The Egan book (one of three), is somewhat of a hard read: You will need to work through his examples in detail to understand them, as if you were reading a text book, and the storyline which is put on top of the physics is just so-so (in my opinion). But, as an example of a book really based on hard physics, there is no other example which is anywhere close. The books are truly unique.

Also note: I found Raft to be mediocre, in comparison to a number of other Baxter novels, some of which I've found quite good. My favorite is the Time Ships, which continues the story of the Time Machine.

Thx!

TomB

Bullgrit said:

Is there a physics/mathmatical reason for the ultimate speed limit, (avoiding saying "speed of light"), to be what it is? Or even to exist at all?

**stuff**

Bullgrit

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Umbran said:

In a word, no. At least, not so far as we understand things at the moment.

**more stuff**.

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Could there be a "terminal velocity of mass-less particles" that is some 300,000,000[+/- a few] meters/second? Just as there is a terminal velocity in Earth atmosphere that is slower then in the vacume of space based on things such as wind resistance of the object, could there be a terminal velocity of light and similar particles? Am I making sense?

Umbran said:

In another thread, we were talking about being unable to really understand the motivations and ways of alien species.

Now, we are not only talking about aliens from another planet. We are talking about aliens from another *universe*. Not just creatures who developed on a different world that follows the same physical laws, but that could be operating under completely different laws.

I would hesitate to assert that their methods of computing* follows how we would go about it.

*If that is what we are experiencing. On the other hand, the "simulation" that is our universe might just be part of the digestive process of a hyper-dimensional being - our experience may be a by-product of a much larger process, for what meaning "larger" has in this context.

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You may not be following my tangent.

If you hand real quantum computers to real programmers today, they will initially program for it in ways similar to how they code for single or multi-processor computers we have now. The fact that it may be able to handle 33 quantum states in stead of our traditional binary will be abstracted into a C-like language that really won't matter, except to somebody who really wants to optimize their code for the Quantum Processor's alien architecture. Additionally, a certain set of computer science problems aren't made better by approaching them "differently". As such, anybody designing a computer may be less likely to design outside of the common pattern than a non-computer scientist might think there would be.

You may also be assuming that the universe simulator we are in was designed by beings unlike ourselves. it is equally possible that the simulator was designed by more advanced versions of us. Just as we make video games to be "realistic" they may have made a universe simulator that is equally "like things used to be". We might be living in the artificial reality version of the GTA to the creators of our universe.

DMMike said:

I read the article, and while I'm no physicist, I have to say that I'm not impressed.

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If the universe fails to impress you, it might be that you're a tad of a tough sell.