A Sense of Perspective

[The Lone Ranger]

http://www.bluedottheatre.com/images/earth-apollo17.jpg

This famous image of the Earth was taken by Apollo 17 astronauts from a distance of only a few thousand miles away. Pretty impressive, is it not?


http://upload.wikimedia.org/wikipedia/commons/7/71/PaleBlueDot.jpg

This picture was taken by the Voyager 1 spacecraft, just after it crossed the orbits of Neptune and Pluto. Though by some definitions it had just left our Solar System, it was still on our Sun's doorstep so to speak, not even out into the galactic front yard yet -- having traveled much less than 1% of the distance to the next-nearest star.

The golden beams you see are beams of sunlight, reflected off the spacecraft and into the camera's lenses. Oh, and that "pale blue dot" that has been circled so that you would notice it? That is the Earth.


"Look again at that dot. That's here. That's home. That's us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilization, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every "superstar," every "supreme leader," every saint and sinner in the history of our species lived there - on a mote of dust suspended in a sunbeam.

"The Earth is a very small stage in a vast cosmic arena. Think of the rivers of blood spilled by all those generals and emperors, so that, in glory and triumph, they could become the momentary masters of a fraction of a dot. Think of the endless cruelties visited by the inhabitants of one corner of this pixel on the scarcely distinguishable inhabitants of some other corner, how frequent their misunderstandings, how eager they are to kill one another, how fervent their hatreds.

"Our posturings, our imagined self-importance, the delusion that we have some privileged position in the Universe, are challenged by this point of pale light. Our planet is a lonely speck in the great enveloping cosmic dark. In our obscurity, in all this vastness, there is no hint that help will come from elsewhere to save us from ourselves.

"The Earth is the only world known so far to harbor life. There is nowhere else, at least in the near future, to which our species could migrate. Visit yes. Settle, not yet. Like it or not, for the moment the Earth is where we make our stand."

--Carl Sagan


Cheers,

Michael

[BDS]

"Look on my works, ye mighty, and despair...." Ozymandias, quoted by a traveler from an antique land, quoted by Shelley.

"Where were you when I hung the stars in the sky?" -- God, talking to Job.

[Uthgar the Brazen]

"Where were you when I hung the stars in the sky?" -- God, talking to Job.

Yeah, well he damned well knows where I was, having just fed me that taco salad he'd made. Cheeky bastard, your deity.

[Dingfod]

But, but, but, we're the most important thing in the whole universe.

[BDS]

“The Sun, with all the planets revolving around it, and depending on it, can still ripen a bunch of grapes as though it had nothing else in the Universe to do.” -- Galileo Galilei


“In answer to the question of why it happened, I offer the modest proposal that our Universe is simply one of those things which happen from time to time.” -- Edward P. Tryon

[LadyShea]

“In answer to the question of why it happened, I offer the modest proposal that our Universe is simply one of those things which happen from time to time.” -- Edward P. Tryon


I like that.

[davidm]

The Copernican Principle holds that there is nothing special about our location in space and time.

And yet, here we are, and the rest of the solar system looks dead. What about the rest of the observable universe? It looks dead, too. SETI has been a failure, so far.

Statistical anlayses show that under the Copernican Principle, we should expect that we are members of a galactic and intergalactic community, with untold numbers of intelligent agents in contact with one another. Yet nothing of the sort is the case.

[Doctor X]

Where is the turtle?

--J.D.

[Watser?]

It reminds me of the Total Perspective Vortex

The man who invented the Total Perspective Vortex did so basically in order to annoy his wife.

Trin Tragula – for that was his name – was a dreamer, a thinker, a speculative philosopher or, as his wife would have it, an idiot. She would nag him incessantly about the utterly inordinate amount of time he spent staring out into space, or mulling over the mechanics of safety pins, or doing spectrographic analyses of pieces of fairy cake.

“Have some sense of proportion!” she would say, sometimes as often as thirty-eight times in a single day.

And so he built the Total Perspective Vortex, just to show her. Into one end he plugged the whole of reality as extrapolated from a piece of fairy cake, and into the other end he plugged his wife: so that when he turned it on she saw in one instant the whole infinity of creation and herself in relation to it.

To Trin Tragula’s horror, the shock completely annihilated her brain; but to his satisfaction he realized that he had proved conclusively that if life is going to exist in a Universe of this size, then the one thing it cannot have is a sense of proportion.

[beyelzu]

The Copernican Principle holds that there is nothing special about our location in space and time.

And yet, here we are, and the rest of the solar system looks dead. What about the rest of the observable universe? It looks dead, too. SETI has been a failure, so far.

Statistical anlayses show that under the Copernican Principle, we should expect that we are members of a galactic and intergalactic community, with untold numbers of intelligent agents in contact with one another. Yet nothing of the sort is the case.

teeming eh?

got a link to the statistical analysis of which you speak?


seems to me that the universe may very well be teeming with life maybe even intelligent life.

that does not necessarily mean that they have avoiding fucking themselves in one of the many ways that we are also in danger of fucking ourselves.

we havent really made it into space yet, maybe it isnt that easy.

[LadyShea]

Statistical anlayses show that under the Copernican Principle, we should expect that we are members of a galactic and intergalactic community, with untold numbers of intelligent agents in contact with one another. Yet nothing of the sort is the case.


I dunno. Seems to me that we have such a small example, our solar system, that it would be impossible to say there are NOT untold numbers of intelligent agents in the Universe.

[ceptimus]

If there were other similar civilizations to our own out there, pumping out radio waves like we do, we'd have heard them already.

Doesn't mean that there aren't other advanced civilizations out there of course, maybe the 'radio wave pumping' phase only lasts a hundred years or so before civilizations find other, cleaner ways to communicate.

If we expect to get to other stars ourselves in the next thousand years or so, then we should expect that if there were other civilizations out there, then a sizeable fraction of them would be at least a thousand years ahead of us, and therefore should already be here.

[fragment]

teeming eh?

got a link to the statistical analysis of which you speak?
Well, there's the Drake equation (http://en.wikipedia.org/wiki/Drake_equation) and the Fermi paradox (http://en.wikipedia.org/wiki/Fermi_Paradox). Not exactly rigorous statistical analyses, but they are attempts to estimate the factors that would affect our chances of encountering alien civilisations.

[The Lone Ranger]

I'm not at all sure we should be expecting the galaxy to be teeming with intelligent life, for several reasons.

First of all, we must understand that from the perspective of SETI, the definition of an "Intelligent Civilization" is one that is broadcasting detectable radio signals and/or that is visiting us. By this standard, we have been an "intelligent civilization" for only about 100 years, and the Earth has supported an intelligent civilization for only 0.000002% of its existence.

And do we have the technology to detect our own radio signals from a trivial distance of only, say, 10 light years? Probably not. Keep in mind that the intensity of a radio signal diminishes with the square of the distance, and the radio broadcasts we're putting out are pretty insignificant compared to what's being broadcast by our friendly neighborhood star, only 93 million miles away. In short, the most powerful radio telescopes currently in existence almost certainly would be incapable of detecting radio signals from planets around even the nearest stars -- unless those signals were very powerful and were deliberately aimed at us.

There are plans for more powerful radio telescopes that could, in theory, detect radio signals from planets around nearby stars, but at present, we don't even have the technology to detect our own civilization from a distance of only 5 light years or so.



The Milky Way Galaxy is approximately 100,000 light-years across, and is about 1,000 light-years thick here in the galactic outskirts. If we make some simplifying assumptions, it works out to a volume of about 7,900,000,000,000 cubic light-years. This means if there are a million "Intelligent Civilizations" in our galaxy broadcasting away like mad, they'd be separated by some 200 light years' distance on average. In this case, the probability that the nearest broadcasting civilization to us is close-enough to be detectable is essentially zero.

So it's extremely unlikely that E.T. will be phoning us anytime soon.


Of course, we have no way of knowing how long an "intelligent civilization" might last. We have been an "intelligent civilization" for only about 100 years, after all. (Marconi's first broadcasts were in the late 1890s, and had a range of only about 1 mile or so.) There's no guarantee that we'll still be broadcasting radio signals 100 years from now -- indeed, it may well be that "intelligent civilizations" have very short life expectancies. I can think of a number of reasons why that's likely.

So, the "window of opportunity" for detecting an alien civilization -- the time during which it has the means to broadcast detectable signals -- may be very short indeed. This further reduces the likelihood of detecting any such civilization, even if one should happen to be quite close to us, galactically speaking.



As for actually going out into space and visiting other star systems, it's extremely likely that this will ever happen. At least, not directly.

You've got to keep in mind just how vast are the distances we're dealing with here. Using the most powerful rockets we could currently build (and the chemical bonds that hold together matter place a limit on how powerful a rocket can be), it's estimated that to accelerate a 50-ton spacecraft (that's only about the size of the Apollo capsule) to 10% the speed of light and get it to the next-nearest star in "only" about 45 years' time would require a volume of fuel roughly the mass of the entire planet. (And that's probably a substantial underestimate.)

Assuming you don't mind taking a few hundred or a few thousand years to reach your target, the fuel cost drops dramatically, but the point remains. There's no foreseeable way to get spacecraft to even the nearest stars without it taking several decades (and more realistically, several centuries) of travel time.

"Wormholes" and "hyperspace" and "warp drive" and whatnot are pure science-fiction. We're talking about the most basic laws of physics here: if you want to accelerate "X" amount of mass to speed "Y," you must expend a certain amount of energy. And to generate that energy, you must expend a certain amount of fuel. To travel interstellar distances in any reasonable amount of time, the fuel requirement is simply enormous.

I suppose it's always conceivable that we'll just happen to find a wormhole somewhere in our Solar System that allows rapid travel to Alpha Centauri or some such place, but I sure wouldn't bet on it.


But if there's no technological solution that will ever make manned interstellar space travel practical, does that mean that exploration of the galaxy will never be possible? Nope. There is a solution, though it will require a great deal of patience.

The solution is to build Von Neumann probes. A Von Neumann probe is a hypothetical class of space probes that would allow a technological civilization to explore an entire galaxy in a reasonable amount of time -- perhaps "only" a few hundred thousand years.

The way it would work is this. You send your probe to a nearby system with instructions to survey the system and then radio back all pertinent information for your grandchildren's edification. Obviously, the probe would have to be quite sophisticated to conduct such a survey all on its own. But what makes the probe so useful is that it is self-replicating. Onboard, it would have its own schematics as well as a manufacturing plant. It would be programmed to mine asteroids or other bodies for raw material, and it would use that material to build copies of itself -- say 100. It would then launch each copy of itself toward another star. Upon arriving at its destination, each probe would repeat the process -- survey the system, report its findings to the home planet, then copy itself and send the copies off to explore new systems. In this way, a civilization could explore the galaxy in a relatively short period of time without ever having to leave home.



Which raises the question of why we haven't encountered any such probes, if the galaxy is teeming with technological civilizations. Maybe our Solar System has been explored by alien machines in the past, and we never detected them. It's certainly possible. Even if it happened recently-enough that we could have detected signals from such a probe, it's by no means guaranteed that the probe's designers would have programmed it to make contact with any civilization it happened to encounter.


***

Then there's the whole question of whether or not it's likely that "intelligence" will evolve. The history of life on Earth doesn't seem too promising on that score. We, being biased, tend to think that intelligence is highly adaptive, and is practically guaranteed to evolve. The history of life on Earth shows no such thing.

For over 80% of the time that life has existed on Earth, it consisted of single-celled organisms only. And don't kid yourselves; ecologically speaking, single-celled organisms are still the dominant organisms on the planet in most ways. If the Earth is at all typical in this regard, it means that if you pick a random moment in a planet's history, you're rather unlikely to find that it supports any sort of multicellular life.

If intelligence (by which I mean human-level intelligence, of course) is so adaptive and so inevitable, it's remarkable that it happens to have evolved only once on our planet. It is, in fact, far from obvious that intelligence is, on the whole, an adaptive trait in the long run.



Of course, there are a lot of stars in our galaxy, and the recent evidence suggests that quite a lot of them have planets orbiting them. So, if I had to bet, I'd bet that there are thousands -- maybe millions -- of planets in our galaxy that support life. Maybe even billions of them.

But I'd lay you good odds that the great majority of those planets have no life more complicated than algae. Of those that do support animal-like life, I'd lay you further odds that only a tiny fraction support what we'd consider "intelligent" life.

Still, there are a lot of planets out there. I certainly wouldn't be surprised to find that there are extraterrestrial civilizations. Indeed, I sincerely hope that there are. But I think it's extremely unlikely that we'll ever meet an alien, or even have a radio "conversation" with one.

Cheers,

Michael

[beyelzu]

teeming eh?

got a link to the statistical analysis of which you speak?
Well, there's the Drake equation (http://en.wikipedia.org/wiki/Drake_equation) and the Fermi paradox (http://en.wikipedia.org/wiki/Fermi_Paradox). Not exactly rigorous statistical analyses, but they are attempts to estimate the factors that would affect our chances of encountering alien civilisations.

yeah, i have heard of both of those and was hoping for something a liitle more concrete that i thought davidm alluded to

[davidm]

Conflict between anthropic reasoning and observation (http://arxiv.org/abs/gr-qc/0303070)

The abstract:

Anthropic reasoning often begins with the premise that we should expect to find ourselves typical among all intelligent observers. However, in the infinite universe predicted by inflation, there are some civilizations which have spread across their galaxies and contain huge numbers of individuals. Unless the proportion of such large civilizations is unreasonably tiny, most observers belong to them. Thus anthropic reasoning predicts that we should find ourselves in such a large civilization, while in fact we do not. There must be an important flaw in our understanding of the structure of the universe and the range of development of civilizations, or in the process of anthropic reasoning.

[BDS]

If the universe is infinite, does that mean that there are an infinite number of snowflakes that are exactly alike?

Or does the infinite nature of diversity trump the infinite number of snowflakes?

[LadyShea]

I don't see any reason to assume that intelligent life elsewhere should include human-like or technological beings.

Dolphins are incredibly intelligent (at least I believe they are based on the evidence I have seen)...but they are not technological.

Isn't it a bit anthropocentric and narrow-minded to assert that for a being to be intelligent it must be in any way similar to us, or trying to contact us, or sending radio waves or whatever?

[Uthgar the Brazen]

I figure if life is out there and is intelligent, it has better sense than to have anything to do with us.

[Sock Puppet]

However, in the infinite universe predicted by inflation, there are some civilizations which have spread across their galaxies and contain huge numbers of individuals. Unless the proportion of such large civilizations is unreasonably tiny, most observers belong to them. I don't get it. If the so-called "light barrier" is insurmountable, then how the hell is this premise possible, let alone inevitable?

[Crumb]

Since when is the universe infinite?

[But]

If there were other similar civilizations to our own out there, pumping out radio waves like we do, we'd have heard them already.


Assuming, of course, that other civilisations consider it worthwhile to pump out radio waves like we do.

What if there is a point in the evolution of intelligence where people (or things or whatever) figure out (if they haven't already all killed each other) that going to distant places in the universe or even attempting communication is for whatever reason completely and utterly pointless?

[BDS]

Since when is the universe infinite?

Since all eternity?

“To see the world in a grain of sand,
And heaven in a wild flower;
Hold infinity in the palm of your hand,
And eternity in an hour.” -- William Blake

[davidm]

Since when is the universe infinite?

The theory of cosmological inflation, which is now well supported by empircal evidence, implies that the universe is infinite (The observable universe is merely its Hubble volume). In an infinite universe, any event with a non-zero chance of happening will happen an infinite number of times. Conclusions: There are an infinite number of inhabited planets. There are an infinite number of planets inhabited by intelligent beings. There are an infinite number of planets that are exact duplicates of Planet Earth, and every person on it. There are an infinite number of variations of Planet Earth, in which every conceivable history, both publicly and your own private history, are played out.

[BDS]

I’m not sure that an infinite universe automatically implies an infinite number of exact duplicates (per my snowflake question earlier). After all, the list of positive integers is infinite, yet there are NO duplicates.

I’m not sure that an infinite universe doesn’t imply infinite duplicates, either.

[Uthgar the Brazen]

After all, the list of positive integers is infinite, yet there are NO duplicates.

Well, there aren't any duplicate positive integers if you stop trying, are there?

n00b.

[Crumb]

But wouldn't only the ones in the observable universe matter?

[JoeP]

at present, we don't even have the technology to detect our own civilization from a distance of only 5 light years or so.

... And yet we still try. Is that a sign of an intelligent civilisation?

Which raises the question of why we haven't encountered any such probes, if the galaxy is teeming with technological civilizations. Maybe our Solar System has been explored by alien machines in the past, and we never detected them.

Or maybe the Galactic Convention outlaws such invasive approaches. "No asteroid may be mined / no star system may be approached without invitation."

[JoeP]

Since when is the universe infinite?

The theory of cosmological inflation, which is now well supported by empircal evidence, implies that the universe is infinite (The observable universe is merely its Hubble volume).

Does it? Why?

All I can see is that it implies that the observable universe is not everything.

[But]

I’m not sure that an infinite universe automatically implies an infinite number of exact duplicates (per my snowflake question earlier). After all, the list of positive integers is infinite, yet there are NO duplicates.


But the number of possible quantum states in any given finite volume is also finite. So either everything repeats itself after a while (it won't - see quantum physics), or every possible finite volume is realized.

[The Lone Ranger]

I don't see any reason to assume that intelligent life elsewhere should include human-like or technological beings.

Dolphins are incredibly intelligent (at least I believe they are based on the evidence I have seen)...but they are not technological.

Isn't it a bit anthropocentric and narrow-minded to assert that for a being to be intelligent it must be in any way similar to us, or trying to contact us, or sending radio waves or whatever?

It is.

That's why it's important to understand that the definition of "intelligent life" from the perspective of SETI is "life that is producing detectable electromagnetic transmissions and/or that is visiting us." That is an awfully narrow definition of "intelligent life," but it's the only form of extraterrestrial intelligence we're capable of detecting, even in theory.

Cheers,

Michael

[beyelzu]

cant we just detect their life signs like in star trek


:tmgrin:

j/k

[The Lone Ranger]

I always wondered how those "life-form sensors" were supposed to work. Seems suspiciously like magic to me ...

Cheers,

Michael

[erimir]

You atheists can stop pretending.

We all know that atheists worship themselves as gods, and view themselves as the most important things in the universe.

You gotta worship something, if it's not God then it's yourself! Or maybe money. Possibly cock.

[The Lone Ranger]

You atheists can stop pretending.

We all know that atheists worship themselves as gods, and view themselves as the most important things in the universe.

You gotta worship something, if it's not God then it's yourself! Or maybe money. Possibly cock.

Look at me! I'm 0.0000000000000000000000000000000000000000000000000000000000000000000000000000000001% of the observable Universe! Worship me!

[beyelzu]

:lol:

[davidm]

First of all, we must understand that from the perspective of SETI, the definition of an "Intelligent Civilization" is one that is broadcasting detectable radio signals and/or that is visiting us. By this standard, we have been an "intelligent civilization" for only about 100 years, and the Earth has supported an intelligent civilization for only 0.000002% of its existence.

And do we have the technology to detect our own radio signals from a trivial distance of only, say, 10 light years? Probably not. Keep in mind that the intensity of a radio signal diminishes with the square of the distance, and the radio broadcasts we're putting out are pretty insignificant compared to what's being broadcast by our friendly neighborhood star, only 93 million miles away. In short, the most powerful radio telescopes currently in existence almost certainly would be incapable of detecting radio signals from planets around even the nearest stars -- unless those signals were very powerful and were deliberately aimed at us.

There are plans for more powerful radio telescopes that could, in theory, detect radio signals from planets around nearby stars, but at present, we don't even have the technology to detect our own civilization from a distance of only 5 light years or so.


What this means is that we ourselves do not meet the search criteria for SETI. SETI is looking for a powerful, deliberately broadcast signal, not merely for radio leakage. We often hear about how "I Love Lucy" programs are now 60 light years away in outer space, implying that cosmic neighbors, if any, could pick up these broadcasts. But they couldn't, for reasons you've indicated. The signal would be too weak.

Since we ourselves don't deliberately broadcast powerful directed signals, why should we think any other civilizations, even assuming they have radio, will do what we do not? If everyone is listening but no one is talking, well ....

Jared Diamond has argued that it makes good sense not to broadcast your whereabouts, on they off chance that "they" are out there. He says if they learn we're here, why, they might come and eat us!

In any event, we'll always have the WOW signal to puzzle over.

[The Lone Ranger]

Some people have argued against SETI for exactly that reason. The general argument is "Why waste time listening for signals? What if everyone is listening and no one is broadcasting?".

There's some logic to this. For us to generate a signal that would be detectable with the technology currently available to us from a distance of 100 light years (practically next door in galactic terms), we'd have to build a transmitter that produces about as much power as does a small star. That seems kind of prohibitive.


And it's true that Jared Diamond and others have argued that it's a bad idea to advertise our presence. Though it's hardly likely that any alien species would consider it worthwhile to cross interstellar space for food, it's conceivable they might decide they don't like us for some reason and therefore launch a great big bomb at us or some such thing.

[Considering the content of a typical television broadcast, I could almost forgive an alien species for deciding that Homo sapiens really shouldn't be allowed to survive.]

Cheers,

Michael

[Dingfod]

Their bomb would need be no more than a city-sized asteroid fired toward earth at a few dozen thousand miles per hour. That would pretty much be the end of life on earth and we'd probably never see it coming.

[davidm]

There's some logic to this. For us to generate a signal that would be detectable with the technology currently available to us from a distance of 100 light years (practically next door in galactic terms), we'd have to build a transmitter that produces about as much power as does a small star. That seems kind of prohibitive.
Michael


If that's the case, what happens if the nearest broadcaster is 100,000 light years away, or in the Andromeda Galaxy?

The more one thinks about SETI, the more futile it seems. :sadcheer:

[davidm]

Their bomb would need be no more than a city-sized asteroid fired toward earth at a few dozen thousand miles per hour. That would pretty much be the end of life on earth and we'd probably never see it coming.


Meteorite collision. (http://www.youtube.com/watch?v=yYgEwXWilUc)

:yipes:

[The Lone Ranger]

Few people appreciate the energy release that would result from a massive object striking the Earth at high speed. Sometimes, the ignorance is downright funny.

I remember watching the movie Alien 4 and laughing at their solution to the alien infestation of the ship. They crashed it into the Earth, figuring the aliens would all be killed in the impact.

So far so good, but if my rough estimates of the mass of the ship and the speed it was traveling at the time of impact are accurate, the energy release at time of impact would easily have been enough to punch right through the Earth's crust and cause an explosion that would wipe out virtually all life on the planet.


Seems like a rather drastic solution to their problem, if you ask me ...

Cheers,

Michael

[JoeP]

we'd have to build a transmitter that produces about as much power as does a small star.

Or ... use a nearby small star :coolsun: and somehow modulate its output. Could we do that?
:sun::cloud::clouds:

:think1:
We are happy to pollute the earth, fill space with radio signal junk and physical debris, why not mess around with the sun. I mean, what's the worst that could happen?

[Dragar]

I’m not sure that an infinite universe automatically implies an infinite number of exact duplicates (per my snowflake question earlier). After all, the list of positive integers is infinite, yet there are NO duplicates.


But the number of possible quantum states in any given finite volume is also finite. So either everything repeats itself after a while (it won't - see quantum physics), or every possible finite volume is realized.

That's not true at all.

[But]

[Considering the content of a typical television broadcast, I could almost forgive an alien species for deciding that Homo sapiens really shouldn't be allowed to survive.]


If they are radical environmentalists, they may hurry to exterminate us all with a bio-weapon attack.

:alien:

[Uthgar the Brazen]

[Considering the content of a typical television broadcast, I could almost forgive an alien species for deciding that Homo sapiens really shouldn't be allowed to survive.]


If they are radical environmentalists, they may hurry to exterminate us all with a bio-weapon attack.

:alien:

They are on a mission to save us from dihydrogen oxide with the power of their truth!

[But]

That's not true at all.

You have to be more precise. How's that not true? Would you agree that in order to try out an infinity of quantum states, you'd have to go to ever higher energies? What do you think happens when your energy comes near sqrt(A/pi) c^4 / G, where A is the area enclosing the hypothetical volume?

[JoeP]

That's not true at all.

You have to be more precise. How's that not true? Would you agree that in order to try out an infinity of quantum states, you'd have to go to ever higher energies? What do you think happens when your energy comes near sqrt(A/pi) c^4 / G, where A is the area enclosing the hypothetical volume?

:popcorn:

[Uthgar the Brazen]

That's not true at all.

You have to be more precise. How's that not true? Would you agree that in order to try out an infinity of quantum states, you'd have to go to ever higher energies? What do you think happens when your energy comes near sqrt(A/pi) c^4 / G, where A is the area enclosing the hypothetical volume?

:popcorn:

Nerd fight! Nerd fight!

:joust:

[But]

Who you calling a nerd? My brother is a fireman.

:nerdy: :fire:

[JoeP]

Who you calling a nerd? My brother is a fireman.

:therapy: And how does that feel? Do you sometimes wish you were more like him?

[Dragar]

That's not true at all.

You have to be more precise. How's that not true? Would you agree that in order to try out an infinity of quantum states, you'd have to go to ever higher energies? What do you think happens when your energy comes near sqrt(A/pi) c^4 / G, where A is the area enclosing the hypothetical volume?

You would indeed need to go toward higher energies to access more energy states, and GR does indeed predict you would wind up with a black hole's event horizon forming outside the hypothetical volume within which the matter has been constrained (though a cryptic equation probably didn't help anyone else understand what you meant).

However, within a black hole's event horizon, GR doesn't say quantum mechanics stops working. You'd simply end up with a more and more massive black hole as you had higher and higher energy states within it.

I'm no expert on quantum field theory, and know nobody who has a working theory of quantum gravity. But I'm pretty certain quantum theory, even including GR, does not predict a finite number of states for a set unit volume. It may be the case a proper theory does. Either way, I'm not convinced by your argument.

[livius drusus]

Dragar! :bigglomp: How've you been?

[Dragar]

Pretty good, but running around madly lately trying to get a flat sorted (got one!), and wrap up with summer project. I'm actually posting from work (shhh!) because my internets is still brokes.

However, another month and I'll be back online full time. And buried under a new load of coursework I imagine!

How's you, and stuff here on FF?

[livius drusus]

Good, good. Other than missing you dreadfully, of course. Yay for your new flat and for you being back full time in a month. Coursework be damned. :cheer:

[But]

I'm no expert on quantum field theory, and know nobody who has a working theory of quantum gravity. But I'm pretty certain quantum theory, even including GR, does not predict a finite number of states for a set unit volume. It may be the case a proper theory does. Either way, I'm not convinced by your argument.

I just thought that davidm's conclusion was justified by the Bekenstein bound alone, which I'm not so sure about after all now.

Although it wasn't the point of my argument, doesn't having a bound on the information in a volume imply a bound on the number of quantum states? Am I making a mistake here?

[Dragar]

It's a bound on the number of degrees of freedom (quantum numbers, or whatever) of the states, not on the the number of possible states, surely?

Heck, it may do. I've barely scratched the surface of GR and QFT. If my argument was convincing, great, but don't put any authority on my opinion!

[davidm]

<derail>

Speaking of perspective, The Galilean Library is the site of the week at American Scientist. (http://www.americanscientist.org/template/SiteOfTheWeekTypeDetail/assetid/55814)

*throws all sense of perspective out window*

:cheer:

</derail>

[beyelzu]

congrats david

very cool

[Stormlight]

Here's the Pale Blue Dot on YouTube:

http://www.youtube.com/watch?v=2pfwY2TNehw

[JoeP]

You would indeed need to go toward higher energies to access more energy states, and GR does indeed predict you would wind up with a black hole's event horizon forming outside the hypothetical volume within which the matter has been constrained (though a cryptic equation probably didn't help anyone else understand what you meant).

... Either way, I'm not convinced by your argument.

:popcorn:

Although it wasn't the point of my argument, doesn't having a bound on the information in a volume imply a bound on the number of quantum states? Am I making a mistake here?

Heck, it may do. I've barely scratched the surface of GR and QFT. If my argument was convincing, great, but don't put any authority on my opinion!

Wait, did they just make up? :sadcheer:

:innocent:

[Uthgar the Brazen]

Wait, did they just make up? :sadcheer:

We all know what that means...






















:showerlv:

[But]

:sadcheer:

If it's any consolation, I'm busy building a double neck guitar / bass with an optical pickup to use as an input device for a game where you have to shoot molecules.

:D

No, really.

[erimir]

Here's the Pale Blue Dot on YouTubeAt first I was wondering why the Pale Blue Dot looked like The Professional.

But I got it.