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Help me Help you with Space

#1 {lang:macro__useroffline}   Rylkan {lang:icon}

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Posted 14 May 2008 - 06:11 PM

I think anyone who has read a majority of my posts know I'm coocoo for Space, but I still am learning alot myself. So I thought it would be fun for people to ask space related questions here, and I can take a crack at answering them for you. It may broach topics I dont know much about, and it helps me with learning how to explain things simply for those who dont have necessarily a strong science background.

So, if you're interested, fire away. TheSmile.gif
#: ssh God@Heaven.org
Password: CurvedSpace
/God> rm *

The BEST error message ever: "Cowardly refusing to create an empty archive."
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#2 {lang:macro__useroffline}   Jake {lang:icon}

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Posted 14 May 2008 - 06:25 PM

So, how big is this space thing anyways?

There's a specific answer I'm looking for. Don't disappoint me.
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#3 {lang:macro__useroffline}   Rylkan {lang:icon}

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Posted 15 May 2008 - 12:54 AM

In terms of the volume that space takes up, if you want to speak of the Universe, it truly is infinite. But the causally connected universe is the Universe we can observe, and theoretically, reach in our theoretical space ship. So this is an easier question to approach. Using arguments about the energy and temperature of the universe, we can find the age of the universe, which is about 13.5 Gyrs. Or 13.5 times 10^9. Mighty big number huh? Multiply this by the speed of light, and you have a causally connected distance.

In metric, you have about 10^26 meters for your radius. Or about 4 * 10^25 feet. So thats a mighty large span that we are connected to.
#: ssh God@Heaven.org
Password: CurvedSpace
/God> rm *

The BEST error message ever: "Cowardly refusing to create an empty archive."
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#4 {lang:macro__useroffline}   Jake {lang:icon}

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Posted 15 May 2008 - 05:58 PM

Ohhh... actually the answer I was looking for was

"Space, is big. Really big. You just won't believe how vastly hugely mindboggingly big it is. I mean you may think it's a long way down the road to the chemist, but that's just peanuts to space."



Seriously though, that's enormous.
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#5 {lang:macro__useroffline}   delta_3mo {lang:icon}

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Posted 15 May 2008 - 09:05 PM

QUOTE (Jake @ May 15 2008, 12:58 PM) <{POST_SNAPBACK}>
Ohhh... actually the answer I was looking for was

"Space, is big. Really big. You just won't believe how vastly hugely mindboggingly big it is. I mean you may think it's a long way down the road to the chemist, but that's just peanuts to space."


TOWELS!!!

Supa pahti! Fantastic spahkaru! Let's gooh nambah waan!


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#6 {lang:macro__useroffline}   Jakethecheesepuff {lang:icon}

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Posted 16 May 2008 - 06:42 AM

TOWELS!
Won't you stay for brunch?
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#7 {lang:macro__useroffline}   Rylkan {lang:icon}

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Posted 16 May 2008 - 11:56 AM

Oy, take the spam elsewhere folks. bluetongue.gif
#: ssh God@Heaven.org
Password: CurvedSpace
/God> rm *

The BEST error message ever: "Cowardly refusing to create an empty archive."
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#8 {lang:macro__useroffline}   Zziggywolf5 {lang:icon}

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Posted 17 May 2008 - 04:41 PM

I'm going to ask something about light, if you don't mind.
Something that has bothered me before: (Correct me on anything if it's wrong. icon_sweatdrop.gif)
Now, if I throw a ball at 50 mph while standing still in a vacuum, the ball moves at 50 mph. If I am somehow moving at 50 mph in a vacuum and I throw the ball at 50 mph, the ball will travel at 100 mph.
From what I understand, light apparently travels at a constant speed in a vacuum.
If I was somehow moving at 50 mph and I shined my flashlight in a vacuum, would the light now move faster than the speed of light in a vacuum?

QUOTE (JGJTan @ Jul 17 2008, 04:48 PM) <{POST_SNAPBACK}>
I endorse stalking. :thumb:
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#9 {lang:macro__useroffline}   Rylkan {lang:icon}

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Posted 17 May 2008 - 05:22 PM

Nope. I can't think of an easy example to prove this to you, but one of the absolutes in the universe that the speed of light is the ultimate speed limit. If I shine a flash light at rest and someone else measures the speed of light, they will measure the same thing if I am moving at 99% of the speed of light when I turn on the flash light. Sorry that I can't give you a reason, but I don't actually think there is one. It is a fact that has been measured and confirmed in varieties of ways. Your intuition about adding Velocities linearly like in a slower frame is actually very technically incorrect as well, it's just that at low speeds it doesn't amount to very much difference.

As two fun side notes, you can slow light down so things can go faster than light, given the light is in a certain medium. Things like Chernakov radiation use this effect. The other thing is, the phase velocity is limited by the speed of light. In a wave there is a group velocity and a phase velocity, and it's thought to be possible to have group velocities greater than c. Our professor gave us a problem where this happened, and I still don't understand exactly why it can do this, but hey, that's a totally different question. bluetongue.gif
#: ssh God@Heaven.org
Password: CurvedSpace
/God> rm *

The BEST error message ever: "Cowardly refusing to create an empty archive."
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#10 {lang:macro__useroffline}   Jake {lang:icon}

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Posted 17 May 2008 - 06:13 PM

Heh, I remember asking you that in GW a while back.

Anyway, from my understanding black holes are basically normal matter under so much pressure that it's structure breaks down into either a singularity, or just something incredibly small. Basically, like a neutron star taken to the extreme.
So, would it be possible that a black hole becomes so massive (I'm assuming this will take a very, very long time to accomplish) that the pressure of the matter inside defeats it's own gravity and basically makes it explode like a supernova on steroids?
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#11 {lang:macro__useroffline}   Rylkan {lang:icon}

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Posted 17 May 2008 - 10:17 PM

The answer is no, but for alot simpler reason than you may think. Where would the force outward come from? Pressure as you are thinking of it, where matter pushes back when you apply some external force to it, is because of various forces in the material. In a black hole, you've gone to the extreme, and just punched the bloody snot out of that matter to the point it can't keep itself together through material stress alone. (In fact, I believe it is about 8 Jupiter masses where Gravity starts beating material stress. So even our star cant hold itself up this way.)

So that leaves other kinds of forces. But really, where would they come from? You can't get it from fusion like in a star, right before it collapses to a black hole the part that becomes a black hole is essentially iron, which just shy of Nickel 62 has the highest binding energy you can find. What that means is it cant get anywhere near enough energy out to counteract gravity anymore, so the star just falls in on itself.

Mind you, we don't know much about the innards of black holes, so we're using some vary simple physics that is true anywhere to argue this. It's pretty much along the lines of where would you get enough energy to counteract the gravity of the black hole. It would take infinite energy to accelerate matter to the speed of light, and light itself can't escape the event horizon, so you're in a jam.

Two neat side notes though.

1) If you want to RADIATE a black hole away, that's perfectly possible. After another scientist proposed the idea, Hawkings sat down and figured out using Thermodynamics that blackholes do radiate away light, which means they are losing their rest mass energy. But the cool thing is, the bigger the black hole, the colder and slower it gets. So if you wanted to radiate away a black hole in the time from the Big Bang, it's about the same mass as a mountain that's needed, which is pretty small.

2) This one isn't possible, but mathematically, you can strip a black hole's event horizon off of it. You spin it fast enough, and things fall apart. Sadly, you need to impart energy to the black hole to speed it up, which means you need to spin it faster, and it's a chain you just can't beat.
#: ssh God@Heaven.org
Password: CurvedSpace
/God> rm *

The BEST error message ever: "Cowardly refusing to create an empty archive."
0

#12 {lang:macro__useroffline}   Darkness {lang:icon}

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Posted 20 May 2008 - 04:05 AM

Alright... So is there -any- was to go faster than the speed of light? bluetongue.gif Or rather, to reach planets/solar systems/etc. that are light years away in a reasonable time frame? Like in sci-fi shows? bluetongue.gif Is the concept of a 'hyperdrive' (or such similar words) even possible? I don't mean at our technology, or even any technology we can even plausibly forsee, but knowing what we do now, can we predict -any- way for it to be feasible? XD

Also. What exactly -is- a wormhole, and are they real? If so, is it possible to create a stable one? bluetongue.gif







“In the valley of hope, there is no winter.”

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#13 {lang:macro__useroffline}   Rylkan {lang:icon}

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Posted 20 May 2008 - 11:37 AM

(I'm using the convention that 'c' is the speed of light here)

I'll answer this in two parts. As for moving at greater than the speed of light, that's a question scientists have to raise their hands up in the air about, shrug, and go "Some particles might exist that can do it." As I've heard it, when we truly can unify all the forces (i.e. Quantum Gravity and figuring out how it merges with the strong and weak nuclear forces and the electromagnetic force at high enough energy) we may know. As it stands, the speed of light is kind of like the fence that keeps everyone in their own little playgrounds. Us in ours, and things that may move faster than c, in theirs. So mind you, while we say the speed of light is the fastest thing is, it's the fastest thing we can actually observe, so it still is a pretty nice limit, given everything else is theoretical. bluetongue.gif

So more directly answering your question, I've been curious before about the use of those theoretical particles in space travel. We wouldn't be able to go faster than the speed of light, because we have mass, but if those super c particles can impart momentum in some way to our own world (Which I doubt, otherwise we should be able to observe them) we could have a very effective way to accelerate ships quickly to near c speeds.

As for a back door method, such as wormholes and the like, mathematically, it is possible to create one. You just need negative energy and positive pressure as I remember it. Kind of funky, not impossible, but requires some rather odd material to make. That would be something you could traverse, in theory. Any other kind as a solution to Einsteins theory of General relativity, collapse rather spectacularly. bluetongue.gif

A wormhole is pretty much a solution to General Relativity that connects two "Events" as they are called in the business, where "distance" is zero. I don't know much about it since I am only beginning to study GR, but that sounds like what it would be. Mind you, I dont think anyone knows what form it would take. Big, Small, Purple, Blue? Who knows

Will we be able to create one for our own purposes? I don't see how, but given the crazy stuff mankind has figured out before, who knows. The issue is you have to get to the other end and make the other wormhole as "I" understand it. I am not even sure how one has the two ends technically connected. I suspect is has to do with forming the hole in a very specific way so that you can choose the other place where it takes place by the math involved. And who knows, maybe we'll get lucky and that means we dont have to travel to the other end. It's all up in the air at this point.

Also, neat side point. Placing wormholes in certain places, i.e. High Gravity fields, you can travel back in time theoretically.

Neat stuff. TheSmile.gif
#: ssh God@Heaven.org
Password: CurvedSpace
/God> rm *

The BEST error message ever: "Cowardly refusing to create an empty archive."
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#14 {lang:macro__useroffline}   Jakethecheesepuff {lang:icon}

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Posted 20 May 2008 - 04:42 PM

Why isnt pluto classified as a planet anymore?
Won't you stay for brunch?
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#15 {lang:macro__useroffline}   x.. {lang:icon}

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Posted 20 May 2008 - 04:46 PM

QUOTE (Jakethecheesepuff @ May 20 2008, 05:42 PM) <{POST_SNAPBACK}>
Why isnt pluto classified as a planet anymore?

They found small asteroids similarly sized to it in around the same area, so it's just a small planet for now.
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