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this post was submitted on 25 May 2026
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Memes
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A meme is an idea, behavior, or style that spreads by means of imitation from person to person within a culture and often carries symbolic meaning representing a particular phenomenon or theme.
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Wrong, the expansion doesn't have a speed because it isn't motion. But you have to think about it longer than you'll probably want to before hitting the up or down arrow and/or scrolling.
Best intuition I've heard for this is that "things" can't move faster than light, but not everything is a "thing".
Imagine doing shadow puppets on the wall with a flashlight. You move the bunny left, shadow moves left. The further away the wall is, the faster the apparent speed of the shadow bunny. You might think that, far enough away and with a strong enough light, your shadow bunny would be racing across the sky faster than the speed of light -- and the crazy thing is, you'd be correct! The shadow (absence of light) can move arbitrarily fast. But the light itself is moving at its normal constant speed from the flashlight out into space, perpendicular to the travel of the bunny, like a garden hose spraying water. The time it takes for the shadow to even begin to move is governed by the speed of light. No information can be communicated faster than light because the light travels at the speed of light to illuminate the places where the shadow isn't.
Very eloquent explanation. The one glitch I must point out is that the shadow (or absence of light) can't move faster than light, because the shadow is information and information can't travel faster than light. If it could, you could use a sequence of shadows, coded by length and spacing, for FTL communication.
The shadow has no FTL information here. Watch https://youtu.be/JTvcpdfGUtQ
Ok I watched the video and I get that no information is travelling FTL. "Speed of darkness" is misleading tho, because the light at the shadow's edge has the same "speed" as the shadow.
The edge of the shadow can move across the surface of an object an essentially infinite speed. That's the speed of dark
The shadow moving is more akin to bandwidth of transmission rather than speed of transmission. You still have to wait for the photons (so speed of light) for the information to arrive, even if the "speed" of the shadow appears FTL.
Best analogy I heard for it is if you put a load of dots on a balloon, then inflate it. Are the dots getting further away? Yes. Is there just the same amount of rubber between each dot as when you put the dots on? Yes. Can you measure the relative speed of the dots? Yes! But have they actually gone anywhere? No...ish?
Yeah, but in this case is the universe just the dots on the surface of the balloon or is it the whole balloon with its entire volume? Intuitively I think it's the latter (although there's probably no "hard" edge that's bounding the ends of the universe like the rubber of the balloon), and if that's true, you could measure the speed of one wall getting away from the centre or the speed of two opposite walls getting away from each other.
I could be wrong of course, I'd be happy if someone points out what I might be missing.
No, you completely understand quantum physics, you are one of the elite.
But in the analogy I don’t think we know what the air in the balloon is, we call it expansion. But I don’t know enough to say anymore
We are the dots on the surface of the balloon. Things really far away seem to be moving away from us. Hopefully we can figure out what gravity is because that would have a lot of gravitas I dunno whatever
I’m fairly certain that in the balloon example metaphor, we are two dimensional creatures on the surface of the balloon
Space time itself is expanding which means I will now blow up soon. Yay!
Yeah, when you put the dimensions implication in it it starts making a bit more sense - implying that we're two-dimensional and the third dimension inside the balloon is the things that we don't fully comprehend (yet).
Yep I think you have to imagine dots suspended in space inside the balloon to better get what's going on, and you're right, the "edge" of the universe is definitely nothing like the surface if the balloon. Probably?
Great analogy, and yeah the "ish" is the fun part!
The fun of justifying a reference frame outside the universe. Sorry I'm getting a headache.
You can explain but don't but criticize you are idoltarer and are in degenerate dharma like all Christians nowadays