this post was submitted on 20 Jul 2023

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What if solving interstellar travel isn't about figuring out faster than light propulsion, but how to extend our own lives? (self.askscience)

submitted 1 year ago by danhab99 to c/askscience

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So I was day dreaming and I caught a thought. What if what we understand about physics is actually all there is to understand? What if you objectively cannot move faster than the speed of light because you can't do the time traveling things necessary. This would mean that the only way to travel amongst the stars would be to extend our lives so that a 5000 year trip at the speed of light would represent like 10% of our lifespans. Travel would be attainable but like the way it was when we were sailing ships to the new world.

That's just one practical solution I could think of to stellar travel. Does anyone else have a practical idea?

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[–] [email protected] 20 points 1 year ago (2 children)

You are behind the times on physics advancements buddy! Thanks to the recently discovered concept of relativistic time dilation, a 5000 light year trip at the speed of light will take literally 0 seconds of your lifespan. More practically, travelling in a starship that accelerates at 1G to the halfway point, turns around and decelerates to the destination, you can reach ridiculous distances within a single human lifetime:

shipboard time	distance	earth time
1 year	.263 LY	1.05 Y
2 years	1.13 LY	2.37 Y
3 years	2.82 LY	4.35 Y
4 years	5.80 LY	7.50 Y
5 years	10.9 LY	12.7 Y
10 years	166 LY	168 Y
15 years	2199 LY	2201 Y
20 years	28.8 kLY	28.8 kY
25 years	380 kLY	380 kY
50 years	149 GLy	149 GY
100 years	22.8 ZLy	22.8 ZY

This is the formula to calculate the distance and time:

x(τ) = c**2/a [cosh(τ a/c) - 1]
t(τ) = c/a sinh(τ a/c)

a = 9.8 m/s
c = 3e8 m/s

The formula is hyperbolic, which is why travel distance is not a linear relation of travel time. E.g. given τ = 10 years:

x = 3e8**2/9.8 * (cosh(60*60*24*365*10/2 * 9.8/3e8) - 1) * 2 / (3e8 * 60*60*24*365)
  = 166 light years
t = 3e8/9.8 * sinh(60*60*24*365*10/2 * 9.8/3e8) * 2 / (60*60*24*365)
  = 168 years

[–] danhab99 3 points 1 year ago (3 children)

Wait so the only thing limiting our interstellar travel is money? That's awesome!!!

[–] Aux 18 points 1 year ago

No, the only limit to everything in our lives and in the universe in general is... Energy! Energy is the real currency of the world.

[–] spacedancer 5 points 1 year ago

That, and figuring out how to travel even just a significant fraction of the speed of light.

[–] [email protected] 3 points 1 year ago (1 children)

But what about the bit about not hitting anything whilst travelling at that speed? Even a speck of space dust would do massive damage at those speeds, right?

[–] [email protected] 5 points 1 year ago

Oh yeah, it's like flying the wrong way down the tube of the Large Hadron Collider. The tougher challenge though is like @[email protected] said maintaining 1G acceleration. Following the rocket equation, which is logarithmic, a 50 year multi-stage rocket will be bigger than the universe itself, even if you use some kind of nuclear propulsion 10000 times more efficient than our chemical rockets.

[–] A_A 14 points 1 year ago (3 children)

Built a machine that can repair itself. Send it to a nearby planet. Give it the ability to manufacture human embryos from our genetic code using only inorganic material. Make at least 2 ; let's call them Adam and Eve. Keep this machine somewhere hidden and near them so to guide them and their offsprings for a few milleniums. Someday, if they are mature enough, tell them what happened.

[–] djc0 9 points 1 year ago (1 children)

I think most of us would like the possibility that WE can travel between the stars, not some incredibly disconnected OTHER.

For example, I would like to see Niagara Falls, not send someone there that I’ll never ever connect with again.

[–] A_A 3 points 1 year ago (1 children)

Create a device that can record and then allow to share experiences from other people.

[–] [email protected] 2 points 1 year ago

No need for people at all then, just send another rover / probe.

[–] danhab99 6 points 1 year ago

Duuuuuuuuuuuuude

[–] miket 3 points 1 year ago* (last edited 1 year ago) (2 children)

Read the “How It Unfolds” short story by James S. A. Corey, it is identical to your ideas.

[–] A_A 2 points 1 year ago (2 children)

Ha, thanks ... not available freely online yet it is : https://en.m.wikipedia.org/wiki/James_S._A._Corey
James S. A. Corey (June 27, 2023). How It Unfolds. The Far Reaches. Vol. 1. Amazon. ASIN B0C4R4V6KN

[–] Drunemeton 2 points 1 year ago

Oh man I love “The Expanse” series, but had no idea that James S.A. Corey was 2 people!

So glad to know. Not sure what to do with that info though.

[–] miket 2 points 1 year ago

Ah, it’s included with Kindle Unlimited.

[–] danhab99 1 points 1 year ago

I just bought the entire series, finally something good to read!

[–] [email protected] 6 points 1 year ago (1 children)

It's kind of interesting to think of society like a videogame. Like we put our stats in oil and tech. But not much in biotech. The different style of civilisation advancement we are missing out on could be wild. But we can't go back and play the game from the start again, so we'll never see what that's like.

Could be computers built off of nerves instead of wires. Computers that grow and multiply. I wonder if it could lead to a new understanding of the nature around us and how we all fit and play a role in the galaxy.

Maybe our desire to explore space is immature. There may be whole other types of space that we can't see because we don't have the tech.

[–] Aux 3 points 1 year ago

We already have a lot of biotech and even some biocomputers. The main issue is that bio structures are fragile for our common use cases.

We also have self replicating machines, 3D printers for example. They are as much as alive as viruses as both require some input from the hosts for full replication cycle. It's just that most people don't think about 3D printers as alive and self replicating beings.

[–] [email protected] 1 points 1 year ago (3 children)

I've wondered why no one seems to be seriously putting effort into a genealogical ship. I'd be okay with being the first generation; I can't possibly be the only one.

[–] [email protected] 3 points 1 year ago* (last edited 1 year ago)

You're not the only one, but nobody is interested in giving any of you an all-expenses-paid trip to deep space.

[–] danhab99 2 points 1 year ago

I guess there's a place to be conserned that eventually a society might emerge within the genealogical ship that might cause them to loose their allegiance to the rest of humanity and go their seperate way. We saw this when european colonists came to the new world, they didn't stay loyal to their home governements because of the difficulty to communicate across the ocean and the difficulty the home government would experience projecting their authority. Communication would be just as difficult with a genealogical ship and they might leave us forever, like we'll never see any benefits from the genealogical ship.

And when you think about it that would make the most sense, because even when the final decendants of the genealogical ship find a new home world they'll never come back to earth, their will be no travel. That world would become a different world for people who might not even consider themselves as human.

Conclusion: there's no way to space travel unless a person can travel between worlds and still have enough of their lifespans ahead of themselves to do stuff to contribute to the wider galactic human soceity. Unless you want to live in the cowboy bebop world where the government is too weak to do anything so they have to hire bounty hunters to suppress ~~criminal organizations~~ competing governments, and you don't know who has your better intrest and who's going to protect you from who, be my guest, fracture human soceity before we're truly ready to go out into space. It sure worked out well 100 years ago.

[–] [email protected] 2 points 1 year ago

Where would you go, and what could one ship's crew do there?

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