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I’m not religious but my fav “that’s oddly convenient“ fact is that just by going fast enough you can cross the universe in a human lifetime because of time slo

I’m not religious but my fav “that’s oddly convenient“ fact is that just by going fast enough you can cross the universe in a human lifetime because of time slowing down. As a biologist I find that much more fascinating than all those poor “irreducible complexity” anti-evolution arguments. Perhaps a physicist feels the other way around.

Arnavion 3y ago
Well, you can cross the universe in any amount of time. The human lifetime isn't special in that regard. A photon crosses the universe in zero time, and anything with non-zero mass can get arbitrarily close to zero time.
- dredmorbius 3y ago
  As I've seen this point made in the past, it's that travelling at a constant 1g acceleration the subjective time for an astronaut would be about 45 years in traversing the observable Universe (~14 billion light years). That is, a comfortable and familiar acceleration gives a human-lifetime-equivalent journey (subjective time). If you're planning a round-trip, you'll find rather more time has transpired on what used to be Earth. <https://www.universetoday.com/129086/far-can-travel/ https://www.universetoday.com/129086/far-can-travel/>
  - saalweachter 3y ago
    > If you're planning a round-trip, you'll find rather more time has transpired on what used to be Earth. Or less, depending on the rotation of the universe as a whole.
    - ben_w 3y ago
      Or no return may be possible at any speed/acceleration given the expansion of the universe.
      - dredmorbius 3y ago
        Given that the outbound journey is already technically challenging, that's very nearly quibbling, despite cosmological accuracy.
  - heavenlyblue 3y ago
    That 1g constant acceleration requires practically infinite amounts of energy
    - dredmorbius 3y ago
      True. However it is also the specific context in which the lifetime-universe-traversal concept emerges.
- denton-scratch 3y ago
  > A photon crosses the universe in zero time That is not consistent with my observations.
  - Scarblac 3y ago
    He obviously means from the viewpoint of the photon.
    - denton-scratch 3y ago
      Yeah, sorry: should have added some kind of irony flag. [Edit] Or maybe not; as I understand it, a photon doesn't "experience" time. It can't distinguish zero time from extended time. Everything's "zero time".
Intralexical 3y ago
Multiple universes, perhaps, depending on your cosmology/eschatology: https://en.wikipedia.org/wiki/Tau_Zero https://en.wikipedia.org/wiki/Tau_Zero

Arnavion 3y ago

Well, you can cross the universe in any amount of time. The human lifetime isn't special in that regard. A photon crosses the universe in zero time, and anything with non-zero mass can get arbitrarily close to zero time.

dredmorbius 3y ago
As I've seen this point made in the past, it's that travelling at a constant 1g acceleration the subjective time for an astronaut would be about 45 years in traversing the observable Universe (~14 billion light years). That is, a comfortable and familiar acceleration gives a human-lifetime-equivalent journey (subjective time). If you're planning a round-trip, you'll find rather more time has transpired on what used to be Earth. <https://www.universetoday.com/129086/far-can-travel/ https://www.universetoday.com/129086/far-can-travel/>
- saalweachter 3y ago
  > If you're planning a round-trip, you'll find rather more time has transpired on what used to be Earth. Or less, depending on the rotation of the universe as a whole.
  - ben_w 3y ago
    Or no return may be possible at any speed/acceleration given the expansion of the universe.
    - dredmorbius 3y ago
      Given that the outbound journey is already technically challenging, that's very nearly quibbling, despite cosmological accuracy.
- heavenlyblue 3y ago
  That 1g constant acceleration requires practically infinite amounts of energy
  - dredmorbius 3y ago
    True. However it is also the specific context in which the lifetime-universe-traversal concept emerges.
denton-scratch 3y ago
> A photon crosses the universe in zero time That is not consistent with my observations.
- Scarblac 3y ago
  He obviously means from the viewpoint of the photon.
  - denton-scratch 3y ago
    Yeah, sorry: should have added some kind of irony flag. [Edit] Or maybe not; as I understand it, a photon doesn't "experience" time. It can't distinguish zero time from extended time. Everything's "zero time".

Intralexical 3y ago

Multiple universes, perhaps, depending on your cosmology/eschatology: https://en.wikipedia.org/wiki/Tau_Zero https://en.wikipedia.org/wiki/Tau_Zero