How would a photon-based intelligence work in regard to relativity?

Question

I want to do something interesting with Caleb Scharf’s speculation that hyper-advanced aliens could make themselves immortal by uploading themselves into the cosmic background radiation. These light creatures also quantum entangle their component photons to help with error control. One problem is to figure out how their time perception would work. Since the aliens component particles moves as fast as light, wouldn’t some relativistic law mess with how they experience time?

Answer 1

Your question is pointless. There can't be photon based intelligence.

As stated here:

As a young student, Einstein tried to imagine what an electromagnetic wave would look like from the point of view of a motorcyclist riding alongside it. But we now know, thanks to Einstein himself, that it really doesn't make sense to talk about such observers. [...]

One of the most basic geometrical ideas is intersection. In relativity, we expect that even if different observers disagree about many things, they agree about intersections of world-lines. Either the particles collided or they didn't. The arrow either hit the bull's-eye or it didn't. So although general relativity is far more permissive than Newtonian mechanics about changes of coordinates, there is a restriction that they should be smooth, one-to-one functions. If there was something like a Lorentz transformation for v=c, it wouldn't be one-to-one, so it wouldn't be mathematically compatible with the structure of relativity. (An easy way to see that it can't be one-to-one is that the length contraction would reduce a finite distance to a point.)

What if a system of interacting, massless particles was conscious, and could make observations? The argument given in the preceding paragraph proves that this isn't possible, but let's be more explicit. There are two possibilities. The velocity V of the system's center of mass either moves at c, or it doesn't. If V=c, then all the particles are moving along parallel lines, and therefore they aren't interacting, can't perform computations, and can't be conscious. (This is also consistent with the fact that the proper time s of a particle moving at c is constant, ds=0.) If V is less than c, then the observer's frame of reference isn't moving at c. Either way, we don't get an observer moving at c.

Answer 2

Insofar as we know, photons don't experience time

And this could be an uber-cool aspect of your world. According to relativity — and from the frame reference of the photon — photons instantly arrive at their destination. They experience no lifespan.

Why? Because according to relativity, once you're traveling at the speed of light, time stops.

But your lifeforms don't necessarily have a destination!

Photons, for example, are emitted from a star, travel through the universe, then hit something. From the perspective of that something, that photon may have traveled for 13 billion years to finally cause skin cancer on some poor sucker who just wanted a day at the beach.

But your lifeforms aren't doing that. They're moving around the universe. They may have had a beginning (an "organization" of photons into a coherent and conscious being), but they don't have an end... so long as they don't hit anything.

And that could be an interesting part of your world, too...

Outer space is whomping empty,^{<citation needed>} but it's not empty. There's dust and molecules and atoms floating all over out there. To us it's empty. But to your photonic lifeforms, all that stuff is hazardous to their health! Once a photon impacts with atomic matter, its energy is transferred to that matter and the photon ceases to exist.¹

That's really unhealthy for your photonic lifeforms.

But it's really good for you, because it gives you something you can use to create a crisis-solution device in your worldbuilding or storybuilding.

But let's get back to that stopped time issue

The real question here is, would photonic lifeforms ever notice life such as found here on Earth? Can they notice it? For them all time is stopped. A photon circling a meter-diameter holding pattern over the Earth is still moving at the speed of light. Maybe it sat there doing that for fifty years... but the photon experienced nothing. From the moment it started circling to the moment it hit some feral oxygen atom, it experienced no time.

Which means that interacting with the rest of the universe is a bit of a problem.

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_{¹ That's a simplified statement. Depending on the nature of the object the photon strikes, a number of things can happen. But for the sake of this answer, the simple statement is sufficient.}

Answer 3

Photonic life is impossible before you even introduced general relativity to your question

Life as we know it is formed from particles bound into fixed structures created by electromagnetic forces. You can not make life (or any sort of machine for that matter) out of anything that has no structure. Photons which have no mass, attraction, or repulsion with one another represent one of the least structured subatomic particles you can imagine.

To try to understand this idea better. Imagine you are given a tank full of water, and told to make a car out of it... you will find that liquid water is utterly and completely incapable of being formed into wheels, doors, framing, etc. by virtue of the fact that it lacks structure... photons have far less structure than water, and is thus that much more impossible to make life out of.

But that does not stop you from making an organism that APPEARS to be nothing but light

While photons themselves can not be alive both for structural reasons and for time dilatation reasons as other answers have suggested, you can add some kind of Minovsky Particles to your setting for creating an organism out of some material that meets the physical properties you want without all the annoying limitations of real world physics. Or perhaps your could consider some variation of Destructive Teleportation as a sort of version of what you are asking about.

Some possible solutions include:

OPTION A: Add a new kind of Electron/Proton like set that does not interact with normal matter, but can still emit photons like normal matter. In this case you would have intangible beings that would APPEAR to be made out of nothing but photons, because that is the only aspect of them we could interact with, but they would in fact be made out of this alternative form of matter that does not move any faster than normal matter. In this case time dilation would be a non-issue.

OPTION B: Add a new kind of subatomic particle that is massless like Photons, but has structure giving properties like the electromagnetic forces found in electrons and protons giving your beings both form and the true speed of light. In this case you could have a being that has the physical form of a living being, but is in every other way made out of particles which can best be described as photon like.

In normal matter, electrons orbit the nucleolus at about 2200km/sec... no where near the speed of light, but still pretty impressive speeds. That said, time dilation calculations don't really care how fast things are bobbing and weaving at a subatomic scale, they only care about how fast you move compared to other objects through space. This means you could have a massless lepton orbiting a massless baryon at the true speed of light, but still be on average sitting still compared to its reference frame. So in this since, you could be made out of something like photons and still experience normal time.

That said, if this massless alien where accelerated towards the speed of light compared to a reference frame, it would experience time dilation just like normal matter would.

OPTION C: Light as a medium for data. While you can not actually exist as a living being made out of photons, light is capable of being encoded with information. So, if you want to relax you definition from "a living being" to "the instructions for creating a living being", then you might have some wiggle room with real for true photons. If you consider the possibility that everything about a person could be encoded and shot off into space by a laser, that signal could in theory eventually be used to reconstruct that person. They would not only not experience time while traveling as a beam of photons, they would literally not be themselves at all, only a data representation of who they are. While this form of immortality may seem useless, it is not that unlike the idea of cryostasis. If your aliens want to live forever, but can't because they have not solved immortality yet, the old and dying may opt to be preserved as a sort of transporter signal shot through the dead of space hoping some time in the distant future someone can show up with an FTL ship, pick up thier signal and reconstruct them... or something of that nature.

Answer 4

Perception requires intelligence, intelligence requires a thought-process, and a thought-process requires a "brain" that implements it, and a brain consists of particles that exchange information between each other to come to logical conclusions and make decisions. These "particles" are neurons in a human brain, transistors in a computer or photons in the case of your photonic aliens.

You wrote that "These light creatures also quantum entangle their component photons to help with error control". Is that the medium that is used to exchange information between the photons that make up their "uploaded brain" in the cosmic background radiation? If so, remember that information can't travel instantly (not unless you invent a hypothetical physical effect that allows it). That means their though processes would be limited by how fast their quantum-entangled light particles can exchange information, which would mean that this thought-process would experience time.

Does a thought-process imply consciousness? That's a question for a philosopher to think about.