Does the Past Still Exist?

Sabine Hossenfelder · 7.5M views · 2022 · 16:07

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Fundamental physicsPhilosophy & ethicsexplainer

Why Hacker News recommends it

HN commenters share it as a clear explanation of the block universe and relativity of simultaneity.

What it is

Sabine Hossenfelder explains how special relativity leads to the block universe, in which past, present and future all exist equally, and asks what that means for whether the past still exists.

Recommended by 1 HN commenters across 1 different months, 2022 to 2023.

What Hacker News said

Recommends glennonymous · 2023-07 · on “Telling the Bees”

I haven’t heard anyone express this before, but when it comes to my death and the deaths of others, I take comfort in the idea of the Block Universe. On the Block Universe concept, time isn’t real in the way we think about it—everything that ever happened or will happen exists in a timeless, eternal block of spacetime. (This video by Sabine Hossenfelder explains it nicely: [this video] .) If this is true, then our lives are eternal—not in the way envisioned by religious people, but eternal in a very real sense. It’s true that I am finite in time in exactly the same way that I’m finite in space, but just as I don’t lament the fact that my body isn’t infinitely large, I shouldn’t lament the fact th

Cites ffwd · 2022-07 · on “Does the Past Still Exist?”

I feel like I must be missing something but in the part about the relativity of simultaneity [0] I feel like this is more about the relativity of the observers and the limitations of speed of light than it is about the ontology of time itself? The definition of "now" as when the light hits the mirror on each side is a "constructed" now, a false now if you may. It takes the light longer on the right side than the left side because she is moving through space, all that tells me is that there is no way to communicate a "now" between different observers because there can't be instantaneous communication between observers, not that time itself is relative or physical stuff itself doesn't have a c

Cites CalRobert · 2023-03 · on “A Growing Number of Scientists Are Convinced the Future Influences the Past”

To be fair there is some disagreement over what exactly "the past" _is_. [this video] discusses this a bit.