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Cake day: July 1st, 2023

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  • 0ops@lemm.eetoMemes@lemmy.mltime to think
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    18 hours ago

    It wasn’t matter that “banged”, it was space-time itself. We observe space expanding, and when we extrapolated backwards eventually we found the point when space-time (not necessarily the stuff inside it) was just a single point, and we called that point “the big bang”. That’s just what the current math says of course, but because of the rate of expansion and the speed of light, we can only observe so much of the universe, past and present. Even when we observe far out and way back to soon after the big bang, we don’t see it all, our scope is limited even within space-time. And from what we can observe, nothing indicates a center. For all we know, there isn’t one, just like you can’t paint a dot on the surface of a ball and call it the center of the surface, every point on the ball’s surface has equal claim to that. In that situation relativity is all that there is. Unless there’s a massive breakthrough, it’s looking like the laws of physics won’t permit us to know if a center exists, let alone find it.


  • 0ops@lemm.eetoMemes@lemmy.mltime to think
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    19 hours ago

    With the balloon analogy it’s not about the center of the volume, we ignore the volume and assume that the surface is a 2d universe. That’s what’s impossible to find the center of. I don’t really like that analogy though personally so I’m not going to discuss that one further.

    Just think about it this way: the observable universe can only be so big (because when the expansion between two distant enough objects is faster than the speed of light/causality, they no longer have a means of interacting). We don’t observe any sort of obvious boundary to the universe within our visible portion that we might be able to assume a center based on. So it’s not that we know that there isn’t a center (afaik, someone correct me if I’m wrong), it’s that it’s likely impossible know that there is, let alone find it from our position in the universe. So, we might as well assume that it’s all relative.

    Imagine you woke up on a raft in the middle of the ocean on an alien planet. It’s foggy, you can’t see stars, you can’t see any landmarks at all. There are other things floating in the water too though. There might be a geometric center to that ocean, but you can’t see it, and you have no other hint at where it is. For all you know, the entire planet is ocean and there’s is no center to find. This is sort of the situation we Earthling are in now, except that at least the the rafter can drift and perhaps eventually find and map out a coast. Because our space-time is expanding, our observable universe will never be bigger than it is now.


  • 0ops@lemm.eetoMemes@lemmy.mltime to think
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    19 hours ago

    We can’t really say that for certain. The word “space” as we know it means nothing without the idea of relativity. Earth orbits the sun, the sun orbits the center of the Milky Way, which exists in a nest of clusters and super clusters … and then you get to the edge of the visible universe. My point is, if a universal frame of reference exists, we haven’t found it. “Absolutely stationary” isn’t something we can test for. Everything that we can observe appears to be moving around something, so can we even responsibly assume that there is a universal frame of reference? Or is it safer to assume that relativity all that there is (i.e. space-time has no boundaries)?