Random SF Science Questions

[Curufea]

Re: Random SF Science Questions

 

And, on a spaceship, you can just turn off the gravity so you don't need heavy lifting gear.

[Frenchman]

Re: Random SF Science Questions

 

Allright, heres 'one':

Would it be possible to have two stars, complete with star systems, <1 Light Year apart?

What effects would this have on the planets, if any could exist at all?

Would there be any habitable planets, or ones which could be easily terraformed?

Would it be possible for earth-like life to evolve there?

Assuming positive answers to the above, would gravity radiation in any form from the neighboring star have a noticable effect?

What are some of the other implications for this set up I may not be thinking of?

[Cancer]

Re: Random SF Science Questions

 

Allright, heres 'one':

Would it be possible to have two stars, complete with star systems, >1 Light Year apart?

I'm going to assume you mean < 1 light-year here, not more than.

What effects would this have on the planets, if any could exist at all?

Would there be any habitable planets, or ones which could be easily terraformed?

Would it be possible for earth-like life to evolve there?

Assuming positive answers to the above, would gravity radiation in any form from the neighboring star have a noticable effect?

What are some of the other implications for this set up I may not be thinking of?

1 light-year is roughly 65,000 AU. That's comparable to the outer edge of the Oort Cloud, where the long-period comets spend most of their time. So systems with this separation are going to mess with each others' comet clouds, at the very least. The question is, how big is the effect?

 

It's worth talking about how likely this is and how long the situation will last, for a one-time encounter. Random star velocities in this part of the Galaxy (and these are for Disk stars, which are much more likely to have planets) are on the order of a ten km/sec or so. 1 km/sec = 4.74 AU/year. So with a typical random velocity of 10 km/sec, the condition of being within 1 light-year is going to last something like a few thousand years. (I'm playing fast and loose with "factors of order unity" -- things like two or three -- here, I admit.)

 

Barring really close encounters, that's too short a time to affect the dynamical stability of the planetary system. Weak, more distant encounters can alter orbits radically, but it takes much more time: millions of years, typically. So my guess is that a random close encounter of two planetary systems won't do much to the planets themselves.

 

The other possibility is a long-term association between two stars with planetary systems, and the separation of the two stars being about 65,000 AU. I don't think such a system is going to stay bound, not in this part of the galaxy; the random passage of stars, giant molecular cloud complexes, etc., and the background galactic tides will overcome the weak gravitational binding energy of such a system. I'm not enough a dynamicist to be able to estimate how long that would take, off the top of my head, though I may be able to scratch something up in a few hours.

[Frenchman]

Re: Random SF Science Questions

 

I'm going to assume you mean < 1 light-year here' date=' not more than.[/quote']

I did, thank you, and I corrected myself.

 

Somewhat dissapointing, as I'm thinking of setting a sub-light speed campaign in such a setting.

My interpretation of what you've said is (and please correct me if I'm wrong):

Stars this close to eachother would either move closer and become a binary system/crash into eachother and throw the whole idea of them developing planets into a cocked hat, or move apart after so short a period that they wouldn't affect eachothers development signifigantly.

However, this seems to indicate that two mature star systems could make a close pass like this, a situation which would last for thousands of years before they moved apart or crashed into eachother - which makes a nice campaign backdrop - either the systems are just getting close enough to allow travel and communication between them, or its 600 years on and people are worrying about their descendants impending annihilation

[Thia Halmades]

Re: Random SF Science Questions

 

So. How likely is it - I mean, likely likely, not theoetical likely - theoretically its 100% likely there's another planet, somewhere in the galaxy, supporting life - may not be advanced life, but some kind of life. But what are the ODDS - the actual hard numbers - of coughing up existance? We're on a blue-green planet orbiting a G-class star, IIRC. Lots of water and, having read up on oxygen & atmospheres, I learned that we had an atmosphere before we had life. An atmosphere which was created because we had a massive amount of CO2 and O. We got lucky.

 

How likely is it that it happened to some other planet? What's the nearest star to us that could reasonably support life? Do we even know which it would be? Is it Sid Meier's Alpha Centauri? Is it Sirius?

[Nyrath]

Re: Random SF Science Questions

 

So. How likely is it - I mean' date=' likely likely, not theoetical likely - theoretically its 100% likely there's another planet, somewhere in the galaxy, supporting life - may not be advanced life, but some kind of life. But what are the ODDS - the actual hard numbers - of coughing up existance? [/quote']

That is difficult to quantify.

 

Astronomers Jill Tarter and Margaret Turnbull looked into this. You can read about their methodology here:

http://www.projectrho.com/HabCat.pdf

 

Here is their list of the nearest stars that their methodology says are likely to host human habitable stars:

http://www.projectrho.com/APJ-HABCAT2.zip

 

I have made a few starmaps displaying these stars here:

http://www.projectrho.com/smap12.html

[austenandrews]

Re: Random SF Science Questions

 

And' date=' on a spaceship, you can just turn off the gravity so you don't need heavy lifting gear.[/quote']

Unless you have no artificial gravity and must deal with acceleration effects.

[David Johnston]

Re: Random SF Science Questions

 

And' date=' on a spaceship, you can just turn off the gravity so you don't need heavy lifting gear.[/quote']

 

Even when it is weightless, the inertia of a 2 tonne object is not something you should take lightly.

[Nyrath]

Re: Random SF Science Questions

 

And' date=' on a spaceship, you can just turn off the gravity so you don't need heavy lifting gear.[/quote']

Not to pile on you, but in many SF novels people who live in freefall think there should be a law mandating that basic physics should be taught in a space classroom. Living in a gravity field (like us) gives rise to all sorts of misconceptions. People fall into thing like the mistaken belief that "mass" and "weight" are the same thing.

 

It's not just you Curufea, it is sadly widespread.

 

Illustrative cartoon

 

In freefall, it becomes obvious that mass and weight are not the same thing. A sledge-hammer may float around weightless, but it is just as hard to swing as if it was on Earth.

[austenandrews]

Re: Random SF Science Questions

 

In freefall' date=' it becomes obvious that mass and weight are not the same thing. A sledge-hammer may float around weightless, but it is just as hard to swing as if it was on Earth.[/quote']

Of course, in freefall you can always use a ship's engines to maneuver the vessel around the large object.

[Cancer]

Re: Random SF Science Questions

 

Of course' date=' in freefall you can always use a ship's engines to maneuver the vessel around the large object. [/quote']

That was the theory with Titanic in the North Atlantic, too.

[austenandrews]

Re: Random SF Science Questions

 

That was the theory with Titanic in the North Atlantic' date=' too. [/quote']

*heh* I meant if you put a large object in a cargo hold, instead of moving the object into place, you could move the ship into place. You'd have access to much larger sources of thrust.

[Sundog]

Re: Random SF Science Questions

 

*heh* I meant if you put a large object in a cargo hold' date=' instead of moving the object into place, you could move the ship into place. You'd have access to much larger sources of thrust.[/quote']

 

Sure, but it would still be a trickier and more delicate job than moving the object; it always is , the smaller mass being easier (and more energy efficient) to move than the larger.

 

A better idea: Use a dual block and tackle system, one on each side to keep the chains taut and the item precisely positioned. Put the B&T systems on sliders to move the items around.

[Frenchman]

Re: Random SF Science Questions

 

A better idea: Use a dual block and tackle system' date=' one on each side to keep the chains taut and the item precisely positioned. Put the B&T systems on sliders to move the items around.[/quote']

 

Like a dual Cieling-mounted engine hoist/cherry picker - a really neat contraption that some auto garages mount on their cieling - and theres on in our garage too. It gets in the way of some of the things mounted on the cieling (drop-lights, the air hose) but we mounted it below the lights so its not a bother.

Ours is homemade, but its the same basic principle - mount a mechanical winch onto four (very) strong rails (we used train tracks, and still had to reinforce them - but without gravity that wouldn't be as big a problem), two going in each horizontal direction and the winch held in the square area created by their intersection. Since the rails can slide against eachother, you can move the winch into any position in its plane of movement with relative ease.

I'd image a cubical cargo bay would have this set up on all four walls (they can be moved out of the way of doors) with redundant winchs/mounts, giving them complete three-dimensional control of even the largest objects. The Winch-mounts could be equipped with brakes to slow or halt runaway objects, and tied to the walls to keep something stationary for a long period.

[Curufea]

Re: Random SF Science Questions

 

Not to pile on you' date=' but in many SF novels people who live in freefall think there should be a law mandating that basic physics should be taught in a space classroom. Living in a gravity field [i'](like us)[/i] gives rise to all sorts of misconceptions. People fall into thing like the mistaken belief that "mass" and "weight" are the same thing.

 

It's not just you Curufea, it is sadly widespread.

 

Illustrative cartoon

 

In freefall, it becomes obvious that mass and weight are not the same thing. A sledge-hammer may float around weightless, but it is just as hard to swing as if it was on Earth.

Not a problem. I was generalising to make a point. (i.e. the silliness of the powerloaders in Aliens)

[Basil]

Re: Random SF Science Questions

 

Somewhat dissapointing' date=' as I'm thinking of setting a sub-light speed campaign in such a setting.[/quote']

Note, however, that a system with stars significantly less than 1 lightyear are much more likely. For example, Proxima Centauri (Alpha Centauri C) is about 1/6 of a light-year from Alpha Centauri A-B. This is far enough to make journeys between them difficult, yet close enough to keep the system gravitationally bound.

 

There may be systems with greater separation (up to 1/3 ly or more, at a SWAG); there are many, many systems with lesser separation (all the way down to a fraction of an AU).

 

There's all kinds of systems out there; plenty of ideas to play around with.

[Curufea]

Re: Random SF Science Questions

 

I seem to recall other interesting sytems of a dwarf star orbiting another star (Pulsar) or a black hole near a star. Vaguely recalled from documentaries on TV - I can't give further details unfortunately.

[Nyrath]

Re: Random SF Science Questions

 

Note, however, that a system with stars significantly less than 1 lightyear are much more likely. For example, Proxima Centauri (Alpha Centauri C) is about 1/6 of a light-year from Alpha Centauri A-B. This is far enough to make journeys between them difficult, yet close enough to keep the system gravitationally bound.

 

There may be systems with greater separation (up to 1/3 ly or more, at a SWAG); there are many, many systems with lesser separation (all the way down to a fraction of an AU).

The most infamous example is Zeta(1) Reticuli and Zeta(2) Reticuli, which are separated by a mere 0.146 light year (9230 astronomical units).

 

Another possibility is a star cluster. The Pleiades for instance. It is about 440 light years away from Earth, but the point is that it has about 500 stars crammed into a sphere only 12 light years in diameter.

 

If my slide rule hasn't slipped, this means that the average separation between stars is about 0.8 light years. Probably even lower separation near the core.

[David Johnston]

Re: Random SF Science Questions

 

However, dense clusters like that tend to be packed with juvenile short-lived stars.

[keithcurtis]

Re: Random SF Science Questions

 

Allright, heres 'one':

Would it be possible to have two stars, complete with star systems, <1 Light Year apart?

What effects would this have on the planets, if any could exist at all?

Would there be any habitable planets, or ones which could be easily terraformed?

Would it be possible for earth-like life to evolve there?

Assuming positive answers to the above, would gravity radiation in any form from the neighboring star have a noticable effect?

What are some of the other implications for this set up I may not be thinking of?

 

Actually, I had to research that problem once for a SF game. Here's a really nifty page. I can't believe I still had the link after 7-8 years.

 

http://homepage.sunrise.ch/homepage/schatzer/Alpha-Centauri.html

 

Keith "Never throw anything away" Curtis

[Nyrath]

Re: Random SF Science Questions

 

However' date=' dense clusters like that tend to be packed with juvenile short-lived stars.[/quote']

True, I was avoiding mention of that inconvenient fact.

[Dr. Anomaly]

Re: Random SF Science Questions

 

If you compare that with the diameter of the Earth' date=' about 8000 miles, you can see that the atmosphere hugs the planet pretty closely.[/quote']

(sigh) Geek confession time.

 

A couple of years ago at BotCon (the convention for Transformers fans) a guy I'd met at the convention and I were sitting in the video room, watching episodes of the orignal Transformers series, and having an interesting little debate about some of the gross physical characteristics of Cybertron (diameter, mass, density, and so on). Naturally enough, there was little data to go on, what was shown in the cartoon was often contradictory, and there was only enough for speculation, and pretty open-ended speculation at that. But it was quite enjoyable anyway.

 

Then came a scene that showed all of Cybertron, from space. And a VERY distinct atmosphere haze a good distance out from the surface of the planet. This other guy and I suddenly turned and looked at each other and said in unison: "Scale height!!!!"

 

We said it loudly enough, too, that we got some funny looks from the other people watching the episode.

 

(Nutshell: there are factors about planetary atmosphere depth that relate to planetary mass, density, and so on. By making certain assumptions [or at least using certain assumptions to set upper and lower boundary conditions], it becomes possible to get a MUCH clearer idea of Cybertron's mass and density. And since Cybertron's atmosphere has been shown to be breathable by humans at the surface level, that gave us some decent bounding conditions for our calculations.)

 

Hi. My name is Scott, and I'm a geek...

[Guest Schwarzwald]

Re: Random SF Science Questions

 

(sigh) Geek confession time.

 

A couple of years ago at BotCon (the convention for Transformers fans) a guy I'd met at the convention and I were sitting in the video room, watching episodes of the orignal Transformers series, and having an interesting little debate about some of the gross physical characteristics of Cybertron (diameter, mass, density, and so on). Naturally enough, there was little data to go on, what was shown in the cartoon was often contradictory, and there was only enough for speculation, and pretty open-ended speculation at that. But it was quite enjoyable anyway.

 

Then came a scene that showed all of Cybertron, from space. And a VERY distinct atmosphere haze a good distance out from the surface of the planet. This other guy and I suddenly turned and looked at each other and said in unison: "Scale height!!!!"

 

We said it loudly enough, too, that we got some funny looks from the other people watching the episode.

 

(Nutshell: there are factors about planetary atmosphere depth that relate to planetary mass, density, and so on. By making certain assumptions [or at least using certain assumptions to set upper and lower boundary conditions], it becomes possible to get a MUCH clearer idea of Cybertron's mass and density. And since Cybertron's atmosphere has been shown to be breathable by humans at the surface level, that gave us some decent bounding conditions for our calculations.)

 

Hi. My name is Scott, and I'm a geek...

 

Well, it turned out that cybertron was an artificial planet built by living creatures, the Quintisons. So it's not surprising it had a breathable atmosphere since the quintisons breathed like humans.

[austenandrews]

Re: Random SF Science Questions

 

What's Cybertron, a planet that transforms into the Death Star or something?

[Old Man]

Re: Random SF Science Questions

 

What's Cybertron' date=' a planet that transforms into the Death Star or something?[/quote']

 

No, that was somebody else...