5 ms·

> At 99.999% C, the traveler would take ~11,000 years if we add more 9s, is it possible to reduce that number to within a human lifespan?

santiagobasulto 9d ago
Yes. Time dilation (with respect of the stationary observed) is calculated using the Lorentz factor. At 99.999% of C, the Lorentz factor is ~223.6. It grows pretty quickly as you add more 9s to the fraction. Every two additional 9s multiply the Lorentz factor by ~10. So at 0.99999999999 c, it'd be ~223,607x. 2.5M years / 223,607 is: ~11 years Of course this is all highly theoretical. https://en.wikipedia.org/wiki/Lorentz_factor https://en.wikipedia.org/wiki/Lorentz_factor
- desterothx 9d ago
  The speeds are theoretical (unachievable), time dilation itself is robust and proved (gps wouldn't work as precisely without accounting for it)
  - santiagobasulto 8d ago
    of course I meant that a human made object traveling at those speeds was theoretical, not time dilation itself. Never thought I'd have to clarify that :)
ndsipa_pomu 9d ago
Yes. If you can manage to get arbitrarily close to the speed of light, the amount of perceived time would get arbitrarily close to zero.
ryeights 9d ago
Proper time asymptotically approaches zero here right?
deleted 9d ago
[deleted]
marcyb5st 9d ago
Yeah, it is and the math get's really counterintuitive to grasp since humans (at least me) have trouble thinking in exponential terms. If you accelerate at 1g constantly for 1y you travel 0.5 light years. You do that for 10.5 years and you reach the center of the milky way. You do that for another 4 (~14 total) years and you are in the Andromeda galaxy, and you do that for another 10 years (~24 years total) and you reach what today is considered the edge of the observable universe. By the time you get there you are basically traveling at a rounding error from C.
- rrr_oh_man 9d ago
  > math get's really counterintuitive to grasp People always say that about speed of light stuff, but I don’t get it. Do you have any more examples of counterintuitive math? Because what you’re describing is basically the equivalent to compound interest in finance. (e.g. investing $100 at 10% interest over 10 years results in $260)
  - jeanlucas 9d ago
    One million seconds is 11 days, a billion seconds is 31 years.
    - rrr_oh_man 9d ago
      Thanks! But same here imho: 1,000 seconds = ~0.01 days (~17 min) 1,000,000 seconds = ~11.57 days (~12 days) 1,000,000,000 seconds = ~11,574.07 days (~32 years) 1,000,000,000,000 seconds = ~11,574,074.07 days (~32k years) It all seems quite logical once you put everything into the same unit, I think. Maybe it's just our human calendar/time unit rollercoaster (60*60*24*30*12) that's playing tricks on us here.
      - jeanlucas 9d ago
        Of course it is logical, we are not discussing the math. But it isn't intuitive, you're not used to numbers that big or that grow that fast. Few things go from a million to a billion, especially when related to time.
alex_duf 9d ago
You can but I don't want to see that energy bill
futureshock 9d ago
Of course! You can arrive as quickly as you want as the traveler. You can cross the observable universe in a few hours if you add enough 9’s.
andsoitis 8d ago
> if we add more 9s, is it possible to reduce that number to within a human lifespan? Yes. At 99.99999999% of c it would take 35 years from the perspective of the traveler. However, an observer on earth will still see it taking 2.5m years.

santiagobasulto 9d ago

Yes. Time dilation (with respect of the stationary observed) is calculated using the Lorentz factor. At 99.999% of C, the Lorentz factor is ~223.6. It grows pretty quickly as you add more 9s to the fraction. Every two additional 9s multiply the Lorentz factor by ~10. So at 0.99999999999 c, it'd be ~223,607x. 2.5M years / 223,607 is: ~11 years Of course this is all highly theoretical. https://en.wikipedia.org/wiki/Lorentz_factor https://en.wikipedia.org/wiki/Lorentz_factor

desterothx 9d ago
The speeds are theoretical (unachievable), time dilation itself is robust and proved (gps wouldn't work as precisely without accounting for it)
- santiagobasulto 8d ago
  of course I meant that a human made object traveling at those speeds was theoretical, not time dilation itself. Never thought I'd have to clarify that :)

ndsipa_pomu 9d ago

Yes. If you can manage to get arbitrarily close to the speed of light, the amount of perceived time would get arbitrarily close to zero.

ryeights 9d ago

Proper time asymptotically approaches zero here right?

deleted 9d ago

[deleted]

marcyb5st 9d ago

Yeah, it is and the math get's really counterintuitive to grasp since humans (at least me) have trouble thinking in exponential terms. If you accelerate at 1g constantly for 1y you travel 0.5 light years. You do that for 10.5 years and you reach the center of the milky way. You do that for another 4 (~14 total) years and you are in the Andromeda galaxy, and you do that for another 10 years (~24 years total) and you reach what today is considered the edge of the observable universe. By the time you get there you are basically traveling at a rounding error from C.

rrr_oh_man 9d ago
> math get's really counterintuitive to grasp People always say that about speed of light stuff, but I don’t get it. Do you have any more examples of counterintuitive math? Because what you’re describing is basically the equivalent to compound interest in finance. (e.g. investing $100 at 10% interest over 10 years results in $260)
- jeanlucas 9d ago
  One million seconds is 11 days, a billion seconds is 31 years.
  - rrr_oh_man 9d ago
    Thanks! But same here imho: 1,000 seconds = ~0.01 days (~17 min) 1,000,000 seconds = ~11.57 days (~12 days) 1,000,000,000 seconds = ~11,574.07 days (~32 years) 1,000,000,000,000 seconds = ~11,574,074.07 days (~32k years) It all seems quite logical once you put everything into the same unit, I think. Maybe it's just our human calendar/time unit rollercoaster (60*60*24*30*12) that's playing tricks on us here.
    - jeanlucas 9d ago
      Of course it is logical, we are not discussing the math. But it isn't intuitive, you're not used to numbers that big or that grow that fast. Few things go from a million to a billion, especially when related to time.

alex_duf 9d ago

You can but I don't want to see that energy bill

futureshock 9d ago

Of course! You can arrive as quickly as you want as the traveler. You can cross the observable universe in a few hours if you add enough 9’s.

andsoitis 8d ago

> if we add more 9s, is it possible to reduce that number to within a human lifespan? Yes. At 99.99999999% of c it would take 35 years from the perspective of the traveler. However, an observer on earth will still see it taking 2.5m years.