This May Sound Crazy

[Dombi]

Where exactly, does a planet end and space begin?

Kerbin ends at 70000m

[NeoMorph]

I'm now imagining the Kerbals on their home planet... they get on their computer and up pops a message from a friend...

KWITTER: "HEY... HAVE YOU HEARD ABOUT THIS AWESOME NEW GAME... It's called Human Space Program"

[way2smrt]

Mind = blown

[Deadweasel]

The universe as we know it may very well be "infinite", but between what we (as humans) have seen of the light coming back to us, and M-theory's predictions, it's becoming more and more likely that the truth is that we're living in the aftermath of a massive explosion resulting from the transfer of energy and mass that originated from within another universe, and that the current extent of that explosion is around 14 billion light years across.

There is this interesting image:

Which is a map of the light coming from the most distant point in our known universe that we can see. It's very possible there's even more stuff further out that has already died out, but because we can't see it, it's likely we'll never know how big our universe truly is.

The one thing that most astronomers can agree on so far though, is that our universe (in terms of space that contains, you know, stuff) is finite in size, not infinite (going on forever and ever). There's probably an edge, but what's beyond that, again, we'll probably never know for sure.

[syfyguy64]

The universe isn't infinite.

Search "Heat death" on youtube. But it sure is big, but at the moment, a distance bigger than grahams number, there could be humans, fighting among the stars for their

[Custard Donut (In Space)]

To say the universe is finite doesn't make any logical sense to me, it may well have an edge but if it keeps increasing in size then i assume it is acquiring new space from outside of itself, i have had this conversation before on at least three different occasions and each time it ended the same way, by being told that my question of "where that new space is coming from" is irrelevant, and frankly i find that answer to be unconvincing.

[Monkeh]

If space is infinite....how can it be expanding?

AFAIK the current most popular theory is that the universe is 'saddle' shaped and definitely finite. The 'new' space you mention above me here is not new but stretched old space. Eventually the space we know will tear itself apart at the quantum level and who knows what will happen then. Think of a balloon with 'stars' drawn on the surface. We get no more balloon material as it gets blown up yet the volume it encloses increases...eventually...KABOOM!

Edited July 25, 2013 by Monkeh
Clarification

[Custard Donut (In Space)]

We get no more balloon material as it gets blown up

This is the part i can't understand, in order for a balloon to be blown up it must have space around itself it can expand into, you couldn't inflate a balloon with your hands clamped around it.

[bracknellexile]

This is the part i can't understand, in order for a balloon to be blown up it must have space around itself it can expand into, you couldn't inflate a balloon with your hands clamped around it.

The real-world balloon in the analogy is a curved two-dimensional surface expanding in a three-dimensional space. Yes, the balloon is a three-dimensional thing to us but if you lived in the balloon universe you'd have no concept of 'inside' or 'outside', only the surface of the balloon which is, for you, your universe. It's curved but it's still a two-dimensional space.

The real universe is (for the sake of simplicity) a three-dimensional 'surface' expanding in a four-dimensional 'space'.

[Monkeh]

To say the universe is finite doesn't make any logical sense to me, it may well have an edge but if it keeps increasing in size then i assume it is acquiring new space from outside of itself...

This is the part i can't understand, in order for a balloon to be blown up it must have space around itself it can expand into, you couldn't inflate a balloon with your hands clamped around it.

What the universe is expending into shall never be known. The edge is expanding at light speed, so nothing could ever get through that barrier, some say the edge of the universe is just the light speed barrier and it does in fact go on forever, remember that it's space itself that is expanding, like the balloon material. It could be expanding into absolutely nothing, (not even vacuum which has particles spontaneously being created and destroyed all the time), or custard. It's a question that shall never be answered, well not until we can break the light speed barrier.

If the universe was infinite though then every single direction we looked when observing the heavens would have a star along that line, the night sky would be as bright as day. Obviously this is not the case.

The last book I read on string theory suggested our 3 spatial dimensional universe is one of an infinite number in a stack, like the pages of a book, slowly moving towards and away from each other in 4 dimensional space, when 2 collide we get a big bang and the incredible energies released cause the spontaneous creation of matter and antimatter, e=mc(squared) and all that.

'Brane theory, as in membrane, I believe it was called, fascinating stuff. Have a look at the books of Brian Greene, the elegant universe and the fabric of the cosmos, excellent reads the pair of them.

Edited July 25, 2013 by Monkeh

[little square dot]

If the universe was infinite though then every single direction we looked when observing the heavens would have a star along that line, the night sky would be as bright as day. Obviously this is not the case.

erm... that's a wee bit simplistic, but I don't have time for this discussion now, haha... home(&dog) beckons. =)

[Pingonaut]

Just remember that just because something is possible doesn't mean it exists. The universe is big, not truly infinite, and things are defined by the limits of the universe. I can say there's a planet with rainbows, bunnies, and flying unicorns. That doesn't mean it exists. Obviously, Kerbals are a lot more likely than that.

And Monkeh, no, that's wrong. If it was infinite we'd be seeing new stars and galaxies every day, as light from so far away finds us, since it was too far away to have been seen before. At least that's how I understand it.

[Tw1]

The way I've heard it explained, the universe is not actually expanding into anything. Space itself is expanding in all directions.

[Deadweasel]

Space itself is nothing. There is literally nothing there. No air, no dust, no atoms. That component could very well go on forever, but again, we'll likely never know for sure.

What we consider our universe is that which is composed of matter and energy; the parts that we can see and measure.

As for the theoretical limit to the universe, there is a school of thought that suggests that everything we know of our universe exists in a pocket of space-time that was created when our plane of physicality (what string/M theorists call a membrane, or "brane") was pushed into existence after what we could consider our membrane collided with another, more energy-rich one. These membranes can't really be defined in three dimensional terms too easily, but if you can imagine one rubber sheet floating around filled with energy, then imagine it coming into contact with another more barren one. The point at which they touch creates a violent rift through which the excess energy in one membrane dumps toward the other one.

From our perspective, this would likely look like a massive explosion of energy and matter emanating from a single point in space (the Big Bang). That energy and matter violently expanded outward, and is still doing so today.

Now, again, all of this is being described in three dimensional concepts that the human mind has evolved to interpret, but the math says there are more dimensions than we can perceive. Our membrane exists at one of these higher levels, so we are unable to perceive it the same way it is usually described.

Suffice it to say that the balloon analogue is only scratching the surface (so to speak) when trying to describe this universal expansion. The reality is that, due to the nature of this so-called membrane, an observer at any point in the known universe would see everything in the universe moving away from him or her, as if they were standing at the very point where it all began.

I highly recommend checking out Nova's series called The Elegant Universe (all three hour-long parts, streamed), or read the book it's based on by Brian Greene. It's pretty easy to follow, and will open up a whole new level of understanding for physics nerds like myself.

Edited July 27, 2013 by Deadweasel

[Deadweasel]

The way I've heard it explained, the universe is not actually expanding into anything. Space itself is expanding in all directions.

Yes, exactly. Although, when most people think of space, they're thinking of a literal three dimensional bubble. That model is a bit too simplistic though, because Einstein has already provided the fourth dimension of time. In order for time and space to be expanding at the same time (which observations suggest is exactly what's happening), it would have to be happening within a higher level, like the fifth or higher.

On that note, I've done some thinking about what it must be like to be able to perceive the fifth dimension, and I realized that there's a pretty good idea of that concept brought forward in Star Trek: Deep Space Nine's "prophets" (the wormhole aliens), who perceive all of time and space as one singular instant and place. Mind. Blown.

[Tiron]

If the universe was infinite though then every single direction we looked when observing the heavens would have a star along that line, the night sky would be as bright as day. Obviously this is not the case.

Actually, not really. The stars we see are only the stars IN OUR GALAXY, which is definitely finite. Everything else is so far away we can't see it with the naked eye. But what happens when the Hubble Space Telescope starts looking at really, really high magnifications at a very small part of the sky?

You get the Hubble Deep Field.

Do it again, in a different spot? You get the Hubble Deep Field South

Do it again in a third spot, only this time look at an even smaller part of the sky even more closely? The Hubble Ultra Deep Field

Take part of the Ultra-deep field, and refine it to go even DEEPER? The Hubble Extreme Deep Field.

Notice anything? No matter how closely it looks and where, it looks almost exactly the same. Thousands and Thousands of entire Galaxies that can't even close to be seen with the naked eye. Apparently in every direction.

Some models of the universe allow for a sort of 'horizon', at which point objects on the other side of it are effectively moving away from your position faster than the speed of light (Some trick with the expansion of the universe, I think, and I think it's more complicated than that but I'm really bad on advanced physics, never having taken a class in it). Basically, we couldn't see anything that was the on the other side of that 'horizon'. We wouldn't be able to tell what was past it, if anything, making it impossible to determine the size of the universe.

It's part of the reason why you hear serious astronomers talking about 'the Observable Universe' when most people would just say 'the Universe', they're allowing for things existing that we can't observe. Like Dark Matter and the theoretical Dark Energy (although 'Dark Energy' always seemed to me like it's probably one of those kludges that's been thrown in because there's some missing bit of the puzzle we haven't figured out yet. They seem to periodically pop up in physics).

[Deadweasel]

(although 'Dark Energy' always seemed to me like it's probably one of those kludges that's been thrown in because there's some missing bit of the puzzle we haven't figured out yet. They seem to periodically pop up in physics).

Really good images you linked there!

And about the dark matter/energy thing: cosmologists and astronomers have basically stated just what you said. Dark matter and energy aren't solid descriptors of things they've actually found; they are "placeholder" names for things they haven't been able to see or measure, but are getting all the indications that something is there just the same.

[Tiron]

Really good images you linked there!

And about the dark matter/energy thing: cosmologists and astronomers have basically stated just what you said. Dark matter and energy aren't solid descriptors of things they've actually found; they are "placeholder" names for things they haven't been able to see or measure, but are getting all the indications that something is there just the same.

I was thinking more along the lines of the 'Luminous Aether', where everyone's like 'oh, light acts like a wave, so there must be a medium to carry it!' and then along comes Michelson and Morley, and it's like 'uhh, we got nothing' (Very clever device they came up with too). And then later it's like 'oh wait, it's a PARTICLE too...wait what?'

Not so much a placeholder as just a 'I don't know well...uh...yeah' kind of wild-speculation that eventually turns out not to be the case at all, because there was some new thing sitting out there completely undiscovered, or we just didn't understand part of the equation quite right.

Given all the problems we're having figuring out gravity, I don't find it at all unlikely.

String theory is all well and good but, well...

Until someone figures out a way to experimentally verify or refute it, it's just a bunch of mostly-useless (but quite elegant, I hear) speculation.

Edited July 27, 2013 by Tiron

[Deadweasel]

I was thinking more along the lines of the 'Luminous Aether', where everyone's like 'oh, light acts like a wave, so there must be a medium to carry it!' and then along comes Michelson and Morley, and it's like 'uhh, we got nothing' (Very clever device they came up with too). And then later it's like 'oh wait, it's a PARTICLE too...wait what?'

Not so much a placeholder as just a 'I don't know well...uh...yeah' kind of wild-speculation that eventually turns out not to be the case at all, because there was some new thing sitting out there completely undiscovered, or we just didn't understand part of the equation quite right.

Given all the problems we're having figuring out gravity, I don't find it at all unlikely.

String theory is all well and good but, well...

Until someone figures out a way to experimentally verify or refute it, it's just a bunch of mostly-useless (but quite elegant, I hear) speculation.

Yeah, that's an argument most contemporary physicist throw down, too. "How can you call it a theory if you can't test against it? Until then it's really just a philosophy."

Newton and Einstein got that here and there too, and now look where we are. I'm sure there will be a development in time that will allow for empirical testing of some aspects of M-theory.

What makes this theory so appealing is the fact that it provides a solution to the conflict between Newton's and Einstein's maths. They simply cannot coexist in the context of the current laws of physics as we know them. Normally this could be safely ignored for the most part, except since their time, we've stumbled on these crazy things like black holes, quasars and gamma ray bursts. The physics that define these things can only really work if we're able to include both sets of math, since we're now talking about things that are incredibly small, and yet fantastically dense. M-theory goes "beneath" both sets of math to find a common factor, but what's crazy is that the math actually works. Granted, that alone isn't really enough to say "This is it; we've found the answer", but it's really too solid and functional to be dismissed as mathematical happenstance.

Also, that comic? I can answer it better. What would that imply? Oh, I dunno, only the possibility of finally possessing a single set of "laws" that define the way the universe works, not to mention paving the way for exploration into OTHER potential universes and technologies that seem just as magical to us today as a Bic lighter would have been to a caveman. That's all. >_>

[Tiron]

Yeah, that's an argument most contemporary physicist throw down, too. "How can you call it a theory if you can't test against it? Until then it's really just a philosophy."

Newton and Einstein got that here and there too, and now look where we are. I'm sure there will be a development in time that will allow for empirical testing of some aspects of M-theory.

What makes this theory so appealing is the fact that it provides a solution to the conflict between Newton's and Einstein's maths. They simply cannot coexist in the context of the current laws of physics as we know them. Normally this could be safely ignored for the most part, except since their time, we've stumbled on these crazy things like black holes, quasars and gamma ray bursts. The physics that define these things can only really work if we're able to include both sets of math, since we're now talking about things that are incredibly small, and yet fantastically dense. M-theory goes "beneath" both sets of math to find a common factor, but what's crazy is that the math actually works. Granted, that alone isn't really enough to say "This is it; we've found the answer", but it's really too solid and functional to be dismissed as mathematical happenstance.

Also, that comic? I can answer it better. What would that imply? Oh, I dunno, only the possibility of finally possessing a single set of "laws" that define the way the universe works, not to mention paving the way for exploration into OTHER potential universes and technologies that seem just as magical to us today as a Bic lighter would have been to a caveman. That's all. >_>

Oh at some point probably someone will figure it out. Until then we get a proliferation of various different theories and not a clue as to which is right, or even if any of them are.

The simple fact the CORE tenant of science is having your theories fit real-world, repeatable scenarios. I wouldn't really call it 'philosophy', (though early philosophers DID spent quite a bit of time trying to puzzle out the nature of the universe) as an exercise in advanced mathematics. Just coming up with a theory that works and is consistent is tricky in and of itself.

I saw a website once where a guy had an idea to basically brute-force create every possible image. Create every possible combination of pixels for an image of a given size. When I thought about that a bit, I realized you would get literally EVERYTHING in that. Most of it would be garbage static of course, but you'd also get an image of every single thing that has, does, or will ever exist. along with every place at every time. every person. You'd get complete how-to guides for every piece of technology ever. A guide to how to make greek fire. Complete, working schematics for a fusion generator. Every Question that has been or will ever be asked, and every answer that will ever be given. And other less savory things, like the pictures Bill used to blackmail the KSP brass.

There's just one problem with all this: For every such correct thing you got, you'd get a virtually infinite number of similar but wrong ones. For every set of fusion reactor schematics, you'd get tremendous numbers of similar but different ones that didn't work. You'd get ones that would immediately blow up in your face. You'd get ones that took more power to run than they produced. There'd be so much of this 'close but not quite' junk that you'd never be able to extract any useful information from it, because you couldn't tell what was real and what was chaff. Some of it you could probably verify through various means, but bits of it (the many, many, many pictures of other solar systems for example), you'd have to actually FIND them to verify it. And a lot of the ones that turn out not to actually exist you'd never be able to prove it.

'String' theory, whatever you want to call it, is in a state similar to that at the moment. There's a LOT of information, but no way to pick out what of it's useful and what's not. Sure, we'll most likely develop the means and the theory to figure it out at some point, but right now it's just a bunch of interesting pictures.

Edited July 27, 2013 by Tiron

[KSK]

Why can't a Kerbal be born small, and their heads grow as they get older? This happens for marsupials.

Marsupial is what I figured. I don't think kerbals have the patience for sitting on a nest hatching out eggs With regard to the evolutionary advantage of a large head and eyeballs - you're assuming that a kerbal's head just contains its brain. No reason why that nice protective bone casing couldn't be holding a bunch of other important organs. Big eyes - omnidirectional vision. Spot your enemies from above, below and side to side as well as forward. Sounds like a big advantage to me

Alternative thought - kerbals have a very large visual cortex to cope with omnidirectional vision. Hence bigger brain, hence bigger head required.

With regard to infinity - yeah it's just a concept rather than a very big number. You can also get different sized infinities that are all infinite if that makes any sense. Example - start counting from 1. You can go as far as you like and in fact there is an infinity of countable numbers. Therefore there must also be an infinity of fractions between each countable number (1/2, 1/3, 1/4 ...) Giving you an infinity that contains an infinite amount of other infinities.

It's at that point that my brain usually explodes too

[Custard Donut (In Space)]

I feel humbled after reading all this, i have memories of what the universe and the night sky look like in my head, but when i see it in photographs it becomes far more overpowering, those galaxies looking like stars are pretty incredible.

[Hiddos]

Everything in the universe exists somewhere, it's just a matter of scale.

That doesn't seem entirely true, tbh

I believe in alien life but I don't think it'll look anything like the Kerbals

[LeonG17]

With the size of the universe, then it's likely to find the Kerbal species out there, it's more a question of how close are they to us?

As mad as it sounds, I don't like the idea of having Kerbals near us, I don't want Jeb to crash SRBs into us.

[Rareden]

not likely if your saying that a kerbin exists at the same size then no, planet that small couldnt hold a thick enough atmo and have liquid water plus a magnetosphere