If we found another living planet

catallus

ScumLord wrote: »

It is the answer to the exact question you asked.

Please let us not go down this rabbit hole

We were talking about gravity.

It's like jelly, I get it now.

Maximus Alexander

ScumLord wrote: »

No, the observable universe is just the bit we can see. Our telescopes have limits, any observatories we have on earth have the problem of looking through our atmosphere to deal with. The hubble in space is our best telescope and the problem you have with that one is that when it looked at one tiny supposedly empty bit of space for a few weeks it found a couple of billion galaxies. Observable space get's bigger every day, it's just a matter of getting around to observing it.

Just to clarify, the observable universe doesn't relate to the ability of our telescopes to see things. It refers to the fact that it is, in principle, possible to observe it. There are lots of things in the observable universe that we can't actually observe for various reasons.

Indeed, due to the expansion of space, there are galaxies that are in the observable universe right now but will cross the cosmological horizon in the future and leave the observable universe. For all intents and purposes, they will no longer exist as far as we're concerned. They will never again interact with our part of the universe. No signal of any kind can ever again reach this part of the universe.

ScumLord

Maximus Alexander wrote: »

It refers to the fact that it is, in principle, possible to observe it. There are lots of things in the observable universe that we can't actually observe for various reasons.

So it's just so far away that the light doesn't have enough energy to get to us? We could see them we'd just have to travel to the edge of our observable universe?

Maximus Alexander

ScumLord wrote: »

So it's just so far away that the light doesn't have enough energy to get to us? We could see them we'd just have to travel to the edge of our observable universe?

No, the expansion of space is related to its volume.

So, say, a cubic kiloparsec expands at a particular rate which is consistent throughout the universe. The more kiloparsecs between your galaxy and another, the faster the space between you is expanding.

For objects that are distant enough, the space between you is expanding at close to the speed of light. A little bit farther and it's expanding faster than the speed of light, so no information from that object will ever be able to reach you again. Even the photons heading right at you are moving away from you at that stage.

We see this as distant galaxies being redshifted. The expansion of space stretches the light, reddening it, until eventually it's infra-red, then radio, then... gone.

So, travelling towards the edge of the observable universe won't help you - you could never get there fast enough.

ScumLord

Maximus Alexander wrote: »

For objects that are distant enough, the space between you is expanding at close to the speed of light.

Oh yes, I see now, it's a cumulative effect.

So, travelling towards the edge of the observable universe won't help you - you could never get there fast enough.

Unless we get warp drive.

Maximus Alexander

ScumLord wrote: »

Unless we get warp drive.

Hah! It's part of the reason I think warp drive really is just a fantasy. It seems to break too many things.

ScumLord

Maximus Alexander wrote: »

Hah! It's part of the reason I think warp drive really is just a fantasy. It seems to break too many things.

I think they know what needs to happen to make it work it's just there's no conceivable way to achieve it, yet.

From the sounds of it though, even with warp drive there's enough in the observable universe to keep us busy that it's probably a bit pointless trying to go further for the next millennia.

Maximus Alexander

ScumLord wrote: »

I think they know what needs to happen to make it work it's just there's no conceivable way to achieve it, yet.

From the sounds of it though, even with warp drive there's enough in the observable universe to keep us busy that it's probably a bit pointless trying to go further for the next millennia.

As far as my understanding goes, there's nothing in physics that prevents a warp drive. Except that to power it you'd need somewhere in the region of the output of hundreds of suns. I mean, I just find it hard to believe that'll ever be possible, as fun as it may be to think about.

Mick55

Maximus Alexander wrote: »

Not to mention that if you could travel at a significant fraction of C, then time passes more slowly from your perspective. So if you could get your ship moving at 0.99 C (Don't know what energy source you're using mind) you could travel 20 light years out in a year and a half. Of course your family back home would be pretty old when you got home - but if it was a one way trip it wouldn't matter.

Bit of a tangent here but your post got me pondering... Say for example Person A is travelling at 0.99 C like you said above. Time for person A slows down and they transverse 20 light years in one earth year.

Meanwhile back on Earth modern technology breaks the faster than light travel problem and faster than light travel is readily available, say for example the Alcubierre drive.

Someone in a FTL craft ( Craft B ) sets off on exactly the same path as our earlier 0.99 C craft which is in a state of experiencing time going slow.

Craft B is travelling so fast they catch up on Craft A. Craft B is experiencing time normally where Craft A is experiencing time going much more slowly. When the two crafts come within view of each other what do they see? ( Say Craft B adjusts it's speed so as not to fly by too fast ).

ScumLord

Maximus Alexander wrote: »

As far as my understanding goes, there's nothing in physics that prevents a warp drive. Except that to power it you'd need somewhere in the region of the output of hundreds of suns. I mean, I just find it hard to believe that'll ever be possible, as fun as it may be to think about.

It's seems impossible but it wouldn't be the first time we've made the seemingly impossible, possible. It is possible if we move into space that we could even just harness a stars energy. I think the problems of scale and power will change in space, many of the safety concerns aren't as great, and you don't have the same constraints on building very large facilities.

Maximus Alexander

Mick55 wrote: »

Bit of a tangent here but your post got me pondering... Say for example Person A is travelling at 0.99 C like you said above. Time for person A slows down and they transverse 20 light years in one earth year.

Meanwhile back on Earth modern technology breaks the faster than light travel problem and faster than light travel is readily available, say for example the Alcubierre drive.

Someone in a FTL craft ( Craft B ) sets off on exactly the same path as our earlier 0.99 C craft which is in a state of experiencing time going slow.

Craft B is travelling so fast they catch up on Craft A. Craft B is experiencing time normally where Craft A is experiencing time going much more slowly. When the two crafts come within view of each other what do they see? ( Say Craft B adjusts it's speed so as not to fly by too fast ).

Honestly, I have no idea. I know the Alcubierre drive involves compressing spacetime, but I don't know what would happen to a beam of light reflecting off Craft A when it reached your 'warp bubble'. What would anything outside the bubble look like to you, is an equally interesting question, but I suspect there'd be some pretty involved maths required in figuring it out.

As a pure guess, I'd say the people on Craft A would look like they were moving really, really slowly.

ScumLord

If the warp drive is creating a bubble of normal space and are warping the space in front and behind to move that bit of normal space to where you want it I would suppose you can't see what's inside the bubble and at most you'd see some weird space compression effects as it passed by. Maybe you'd see nothing as the ship isn't really moving in normal space.

Maximus Alexander

ScumLord wrote: »

If the warp drive is creating a bubble of normal space and are warping the space in front and behind to move that bit of normal space to where you want it I would suppose you can't see what's inside the bubble and at most you'd see some weird space compression effects as it passed by. Maybe you'd see nothing as the ship isn't really moving in normal space.

That's another possibility. We need to summon an actual theoretical physicist to confirm for us!

ScumLord

Maximus Alexander wrote: »

That's another possibility. We need to summon an actual theoretical physicist to confirm for us!

Problem is even the smartest people can only make a guess. Hopefully we'll be able to create an AI that's smart enough to design these things. That may actually happen in our lifetime, even if we don't get to see the ships.

seamus

It's a strange question because saying that someone is travelling at 0.99c doesn't mean the same thing it does when we say someone is travelling at 20km/h. Classical mechanics breaks down, so you can't really use classical mechanics to describe what would happen when the two modes of transportation are used side-by-side.

The guy with the warp drive isn't actually travelling at 0.99c and from his perspective the guy travelling at 0.99c is not moving alongside him. It's a all a bit mental and difficult to conceptualise because it falls outside what we intuitively understand about motion.

The most interesting advance in theoretical flight at the moment is this thing: http://en.wikipedia.org/wiki/Quantum_vacuum_plasma_thruster

It's being continually confirmed that it "works", they're close enough to a full confirmation that once they publish something that can be peer-reviewed, they can begin looking at how to develop propulsion from it.

In layman's terms, the device is capable of producing measurable thrust within a vacuum using nothing more than (lots of) electrical energy. What this means is that a spacecraft would not have to carry millions of tonnes of fuel and instead could rely on a couple of lightweight nuclear reactors.

Capt'n Midnight

sheesh wrote: »

they have grown plants in powdered moon rock afaik ok maybe moon rock analogue

Hydroponics shows that you don't need soil to grow plants.

ScumLord

Capt'n Midnight wrote: »

Hydroponics shows that you don't need soil to grow plants.

Space weed, we now have a reason to go there. I'll pop an email of too Musk.

eoinp11

ScumLord wrote: »

Space weed, we now have a reason to go there. I'll pop an email of too Musk.

As aqua teen says best.. moonajuana.

Look up the dificulties of growing plants on planets with lower gravity.

Interesting to see what difficulties have to be overcome and the fact that people have some reasonable solutions offered up already.

ScumLord

Scientists now think life supporting solar systems are probably going to be multi-planet solar systems a lot like our own. Many solar systems seem to have one or two planets with high eccentricity orbits, elliptical paths which would bring the planet close to it's sun and then far away, so extremes of hot and cold.

The planets in our solar system have low eccentricity so more circular orbits, where we don't get extreme temperature differences over the course of a year, which allows for the conditions were life can evolve.

http://www.pnas.org/content/112/1/20.abstract?sid=3aa94fe6-6060-473d-8156-91567afceabd