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The Universe Within 12.5 Light Years

(www.atlasoftheuniverse.com)
266 points algorithmista | 2 comments | 05 Sep 25 22:20 UTC | HN request time: 1.303s | source
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stephc_int13 ◴[06 Sep 25 01:21 UTC] No.45145686[source]▶
When the Fermi Paradox was first posited, scientists and engineers seemed to believe that interstellar travel was soon to be technologically achievable, a few decades, maybe centuries for the less optimistic. Progress around space propulsion has kind of stalled since then and we should maybe question the possibility of interstellar travel as this would give an easy but unpleasant answer to the famous paradox.
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shireboy ◴[06 Sep 25 01:36 UTC] No.45145776[source]▶
Right- “where are all the aliens?” is answered by either “they don’t exist” or “they do but physics of the universe prevent them from moving between solar systems.”
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VladVladikoff ◴[06 Sep 25 02:17 UTC] No.45146004[source]▶
This feels very defeatist to me. Technology continues to advance, exponentially. And there are hypothetical ultra fast space travel technologies that we haven’t yet been able to fabricate but could theoretically in the future. e.g. Alcubierre warp drive.
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1. freakynit ◴[06 Sep 25 05:27 UTC] No.45146852[source]▶
The fabric of spacetime itself sets the ultimate speed limit. Nothing can locally move through it faster than light. For example, gravitational waves ripple across the universe at light speed.

Anything that exists within spacetime is bound by this rule. The only odd exception people point to is quantum entanglement, but while the correlations appear instantaneous, they can’t be used to send information faster than light. Sending matter is distant second.

So, if we ever hope to travel faster than light, we wouldn’t do it by "outrunning" gravity. Instead, we’d need to find a way to manipulate spacetime itself, like bending, warping, or reshaping it ... since that, in the first place itself, is what is defining the limits of motion.

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2. oneshtein ◴[06 Sep 25 08:37 UTC] No.45147631[source]▶
So c is the speed of light in the fabric, right?