Planck Telescope Is Coolest Spacecraft Ever 196
Hugh Pickens writes "Launched in May, BBC reports that Europe's Planck observatory has reached its operating temperature, a staggering minus 273.05C — just a tenth of a degree above what scientists term "absolute zero." and although laboratory set-ups have got closer to absolute zero than Planck, researchers say it is unlikely there is anywhere in space currently that is colder than their astronomical satellite. This frigidity should ensure the bolometers will be at their most sensitive as they look for variations in the temperature of the Cosmic Microwave Background (CMB) that are about a million times smaller than one degree — comparable to measuring from Earth the heat produced by a rabbit sitting on the Moon. Planck has been sent to an observation position around the second Lagrange point of the Sun-Earth system, L2, some 1.5 million km from Earth and Planck will help provide answers to one of the most important sets of questions asked in modern science — how did the Universe begin, how did it evolve to the state we observe today, and how will it continue to evolve in the future. Planck's objectives include mapping of Cosmic Microwave Background anisotropies with improved sensitivity and angular resolution, determination of the Hubble constant, testing inflationary models of the early Universe, and measuring amplitude of structures in Cosmic Microwave Background. 'We will be probing regimes that have never been studied before where the physics is very, very uncertain,' says Planck investigator Professor George Efstathiou from Cambridge University. 'It's possible we could find a signature from before the Big Bang; or it's possible we could find the signature of another Universe and then we'd have experimental evidence that we are part of a multi-verse.'"
rabit from the moon (Score:1)
Is anyone else dissapointed we don't already have this capability? I can stream Top Gear in HD from youtube in faster than real time but we lag this far behind in (optical? thermal?) imaging? I know the atmosphere creates a lot of optical distortion... but really? Not even a rabbit (which have unusually high body temps if I recall correctly)?
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Uh, yea. Atmopheric distrotion is bad enough for visible radiation...thermal would basically be a second level of distortion.
Re:rabit from the moon (Score:5, Funny)
I just want to know how long the rabbit's been sitting there. I mean, is it still a living rabbit, and does it get hotter for a few seconds as it thrashes around without breath in the moon's almost nonexistent atmosphere?
Or do scientists just know how hot SPACE RABBITS get? When will the invasion come?
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Re:rabit from the moon (Score:5, Informative)
According to Japanese and Aztek folklore [wikipedia.org], a rabbit has been there for a long time. I could never really make out the face or the rabbit in the moon's craters when I look.
Ryan Fenton
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MUAD'DIB: the adapted kangaroo mouse of Arrakis, a creature associated in the Fremen earth-spirit mythology with a design visible on the planet's second moon. This creature is admired by Fremen for its ability to survive in the open desert. [1]
[1] Herbert, Frank. Dune. 1965.
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Yikes, it's fucking huge.
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Now that we know of their retreat to the moon, make no mistake, they are building their numbers rapidly. The space rabbit invasion will come.
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If you ever see a hot moon rabbit just don't look her in the eye for your sanity's sake.
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That was '72, the goodies came to our rescue and defeated big bunny's transistorized carrots [myspace.com] in '73.
Re:rabit from the moon (Score:4, Funny)
I'm just disappointed they couldn't find a way to turn it into a car analogy instead of rabbits.
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Volkswagen makes a model of car called the Rabbit.... what makes you so sure it isn't a car analogy?
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Dude! Same thing! http://www.vw.com/rabbit/en/us/ [vw.com] ^^
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Is anyone else dissapointed we don't already have this capability?
I'm actually a little disappointed that this wasn't expressed in standard metric terms. I thought here on Slashdot, the agreed upon standard was something in terms of libraries of congress. Is there a conversion factor or something we can apply here?
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Re:rabit from the moon (Score:4, Informative)
We know that entropy=k*ln(O) where k is the Boltzmann constant and O is the number of microstates of the system. If we really wanted, we could express the number of microstates as 1 LoC, since both are really just measuring information in one way or another.
Now if you recall temperature = change in heat/change in entropy. The average body temperature of a rabbit is about 312 degrees kelvin according to google.
To get a change in entropy and heat, we can look at both over an arbitrary time step t, so 312 K [one rabbit]=(heat/t)/(k*ln(2TB [one Library of Congress])/t)
Solving for one Library of Congress, we get one Library of Congress = e^(k*heat [in joules]/312 degrees K)=e^(4.4252x10^-26 joules^2/(degree kelvin)^2)
Now assuming a rabbit is about 0.2 meters in diameter, at a distance of about 384,000 km, that's about 3*10^-8 degrees.
So, putting that all together, the conversion factor is about e^(4.4252x10^-26 joules^2/(degree kelvin)^2)*1.1*10^5 arc seconds.
Hope that clears things up for you!
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How many station wagons do you get per truck ?
Re:rabit from the moon (Score:5, Insightful)
Is anyone else dissapointed we don't already have this capability? I can stream Top Gear in HD from youtube in faster than real time but we lag this far behind in (optical? thermal?) imaging? I know the atmosphere creates a lot of optical distortion... but really? Not even a rabbit (which have unusually high body temps if I recall correctly)?
Actually, that's an interesting question. It has been answered in this thread but I'd like to address a deeper issue here. Technical challenges usually come in two flavors, one which can be solved simply by making a device better and better and the other, which has to do with the signal you're trying to measure just not being there (or is otherwise masked by "noise"). I put "noise" in quotes because people always assume the signal can be separated from the noise. Not so. In most cases, you have to know the source of the noise to reliably subtract it out. In other cases, you can be lucky and the noise will be random so that greater averaging of the data filters out the noise automatically. For ALL other cases, people have to resort to making assumptions about the noise, which means that the "filtered signal" you end up with has (sometimes huge) contributions from the person who made the assumption. Is it a rabbit or an artifact of my assumptions?
:).
This particular question you raise is in that final category. There just isn't enough signal there that is distinguishable from the surrounding crap for you to tell with any certainty that you have rabbits on the moon and not a migratory bird flock here in the sky. You could always throw money at the problem (in principle) by having a dozen weather satellites constantly monitoring the patch of atmosphere in direct line of sight between you and the moon and feeding you detailed real-time data of temperature, pressure, index of refraction, chemical composition of air(/dust) in there (affects absorption/reflection/transmission). THEN, you MIGHT stand a good chance of catching a glimpse of your elusive rabbit.
Technology can always be improved. Ambient conditions will always be the ultimate threshold for the actual utility of that technology.
That is not to say that a particular phenomenon always stays of out of reach. One simply realizes that certain constraints stated in the problem are actually ridiculous. For instance, if the goal was really to observe rabbits on the moon, the constraint that the instrument be on the earth is highly artificial. Instead, one would relax that constraint, put a satellite above the atmosphere, satisfy one's rabbit fetish and the problem's solved
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Just a little nitpicking. Noise randomness doesn't mean that you'll get a good estimation of the signal by averaging.
The mean estimator works all right (it's the MVU, IIRC) when you're getting zero-mean noise, or noise whose PDF is symmetrically distributed around its expected value (in this case, you could correct the bias by extracting the mean of the noise).
But I just flunked an exam on this very topic, so to hell with me :D
You're quite right. I should have been more precise when I said "random". What I meant was zero-mean random so that by repeated averaging (done intelligently), the signal survives while the noise averages out to give a large signal-to-noise. Thanks :)
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Hey diddle diddle,
The cat and the fiddle,
The cow jumped over the moon,
The little dog laughed to see such fun,
And the dish ran away with the spoon.
It seems to be well within the capability of current measurement techniques to determine whether bovines are leaping over natural satellites, so we should be able to figure out if a rodent is sitting on one.
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we should be able to figure out if a rodent is sitting on one.
As any fule knoe, rabbits are considered to be leporids or lagomorphs.
Don't think so. (Score:4, Funny)
They call that a cool space craft? It doesn't even have warp drive, let alone quantum torpedoes. It doesn't even have anything onboard to which you could apply the phase "reverse the polarity". Cool. Bah!
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I'll bet there's plenty of polarity to reverse (Score:2)
They call that a cool space craft? It doesn't even have warp drive, let alone quantum torpedoes. It doesn't even have anything onboard to which you could apply the phase "reverse the polarity". Cool. Bah!
Dude, you can reverse the polarity on anything with a DC circuit. Sometimes, with spectacular results.
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Re:Don't think so. (Score:5, Interesting)
Neat idea, taken a little farther. An advanced civilization prevents a more primitive one from developing advanced physics by making astrophysical observations look funny locally. The primitives assume the weak anthropic principle holds, come up with all these really strange theories about cosmic strings, dark energy and such, and never become competition.
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It doesn't even have anything onboard to which you could apply the phase "reverse the polarity"
Of course it does. I heard it's powered by AA batteries.
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It doesn't even have anything onboard to which you could apply the phase "reverse the polarity".
You can reverse the polarity on anything electrical. Just swap the positive and negative terminals. Don't ever expect to use many of those things you do that to ever again though. Most of the things that die will wimper but some higher voltage things will get dangerous and explode.
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In a device like this, I'm certain they can reverse the polarity on something for some useful purpose. Its just too complex for there not to be SOMETHING.
One Planck telescope for mankind... (Score:2)
That's a pretty small telescope you have there, and it doesn't last very long either ; ).
Signature (Score:1, Funny)
"Sorry for the Inconvenience"
Planck telescope (Score:5, Funny)
The Planck telescope is the smallest telescope that, according to our current understanding of nature, it is meaningful to speak about. This property sets the Planck telescope apart as the natural unit (also called Planck unit) for telescopes.
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The Planck telescope is the smallest telescope that, according to our current understanding of nature, it is meaningful to speak about. This property sets the Planck telescope apart as the natural unit (also called Planck unit) for telescopes.
I think the technical term is telescope quantization. Telescopes can only exist as integer multiples of the Planck telescope.
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And we can call the first repair job, "Walking the Plank".
Worst metaphor ever? (Score:5, Insightful)
A rabbit sitting on the moon will be at a much different temperature than its surroundings, not a millionth of a degree kelvin. The only thing interesting about measuring the temperature of a rabbit on the moon is resolution, not sensitivity. So essentially completely the opposite of what the Planck telescope does.
Sorry, just had to release my inner pedant - this was too good to resist.
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A rabbit sitting on the moon will be at a much different temperature than its surroundings
Not for very long. How's that for pedantry?
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Presumably the rabbit is protected somehow, or else it wouldn't be sitting. Of course, that protection would probably smooth out the variance in the amount of energy being radiated, and so make the measurement process more interesting...
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heat != temperature.
The summary said "heat produced by a rabbit sitting on the Moon". Somehow that went through your brain and came out as "measuring the temperature of a rabbit on the moon". So the problem is you, not the metaphor.
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Er, no. The variation in temperature between the rabbit and its surroundings is substantial. The variance being measured in the microwave background are tiny. The distinction between heat and temperature here doesn't matter (or if it does, you haven't yet explained why).
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Call it a metaphor, call it an illustrating example. The main reason I felt it was not a good example is that doing what the Planck telescope *actually* does is a lot more impressive to me than detecting a rabbit on the moon. The rabbit is so close it might as well be in your living room.
Perhaps both jobs are equally difficult, but mapping variances in the cosmic background radiation to a millionth of a degree kicks ass. Taking snapshots of the energizer bunny on the moon is boring by comparison.
Re:Worst metaphor ever? (Score:4, Funny)
The only thing interesting about measuring the temperature of a rabbit on the moon is resolution
Well yeah, that and the obvious question of "what the hell is a rabbit doing on the moon, and how did it get there?"
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Maybe its measuring the temperature of a human on earth?
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obviously it is suffering an agonizing demise since it doesn't have a pressure suit, O2 supply, or thermal protection.
Won't somebody please think of the MoonRabbits
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If you're going to MacGyver an exposure suit to keep the rabbit alive, you'll probably need some duck tape. Wetsuits don't form a watertight seal, let alone an airtight seal, so you need some way to prevent the air from escaping from the fishbowl.
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Well yeah, that and the obvious question of "what the hell is a rabbit doing on the moon, and how did it get there?"
Obviously it should've taken that left turn at Albuquerque =)
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The Goodies [wikipedia.org] dunnit.
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That's fairly obvious - it's a Suicide Rabbit [wikipedia.org]. Obviously it hitched a ride on the LRO [wikipedia.org]
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Or perhaps it's just a regular Moon Rabbit [wikipedia.org].
Why a rabbit? (Score:2)
NPOV (Score:4, Insightful)
This is where the so-called "neutral point of view" ceases to be useful.
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I scratched my head over this, too.
Why is "absolute zero" in quotes? And what do "people" who aren't "scientists" call "0" on the "temperature scale" that "scientists" term "Kelvin"?
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I think it was a wikipedia meets special relativity pun. Since there can be no absolute reference frame, how can there be an "absolute zero". Maybe, somewhere outside our 4 dimensional reference, an object we think is at complete rest is vibrating and contains energy. Then you match that with Wiki's intended neutral point of view . . .
And if it wasn't a really horrible pun, then maybe the GP was trolling
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I'm not sure that's even the worst infelicity of the summary. The start, "Launched in May, BBC" establishes that BBC (perhaps "the BBC") was launched in May.
In case you're wondering, (Score:1)
that's colder than a witch's titty (-273.04C).
Great... (Score:2)
Planck hath a blog and a twitter! (Score:4, Informative)
For more information you can catch up with Planck on the mission blog [wordpress.com] on Planck's twitter [twitter.com], and on the Planck outreach [cf.ac.uk] website.
I help maintain the blog and work on both the Planck and Herschel [wordpress.com] missions.
Stupid units (Score:4, Informative)
indicates how close to absolute zero it is - and even is easier to grasp in my opinion.
Come on, we're on Slashdot, dammit!
Re:some 1.5 million km from Earth? (Score:5, Informative)
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Wikipedia has an excellent article [wikipedia.org] describing each of the Legrangian points and why each of them is pseudo-stable.
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You did a lot of typing in your post. I think perhaps you could have saved a lot of it in your quest to enlightenment if you'd have chosen a text field on a different web page. May I suggest http://google.com/ [google.com] and the phrase "earth sun l2"? The first link even has a very descriptive map. http://en.wikipedia.org/wiki/Lagrangian_point [wikipedia.org]
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People just don't read Gertrude Stein any more.
rj
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"Why is it so hard for people to understand that there is no "before the big bang"? Time was created at the big bang."
That's certainly an interesting hypothesis. In what way do you propose we test it out?
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I think we can figure it out once we understand what mass is.
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"It is something that should be true or false by definition."
I don't know anything about the definition of Big Bang including the idea that time began with it. As far as I know Big Bang is the name for the explosive expansion of all matter in the universe at some point in the past from a primeval dense condition.
That time originated there as well is just a theory, nothing definitional about it as far as I know.
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That time originated there as well is just a theory, nothing definitional about it as far as I know.
This [wikipedia.org] may be an interesting read and likely what the GP meant, but in short: you can't say what's going "back" and what's going "forwards" in time without measuring entropy, and you can't do that without an universe. Though IANAP so perhaps I'm not understanding the page right, so dunno.
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false, that is just one model of what the "big bang" is, there are many more, some with time extending before the big bang. as soon as you start running off at the mouth about "space-time" you show yourself to be constrained to variations of the G.R. model. There are more models than you have pairs of socks.
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Utter bollocks. Theory is a term that is in no way used with such precision, even in science. See string theory etc etc.
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The big bang is not a definition. It, and the details of what got created how/when and what happened shortly after and whether it's meaningful to talk about "before" are all hypotheses and theories, not definitions.
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[quote]the Christian Bible is true, and there is every indication that it is,[/quote]
Other than the universe being six thousand years old.
And other than Noah's flood.
And other than rainbows not existing since always, but instead having been made into existence since the flood of Noah.
And other than the tower of Babel.
And other than lots of other things, too, which are about as unscientific as any other mythology.
[quote]you will stand before God at the judgment and then you will care. [/quote]
Strangely enoug
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For your statement to make sense, you assumed the same property "time" exists within and outside the universe, and that it made sense to connect the two. It is like saying since Earth existed within something larger, there might be something due North of Earth's North Pole.
Unfortunately, North/South is a local property of Earth, while there is plenty space above the North Pole, you cannot go more north from the North Pole. Similarly, spacetime is a property of our observable universe, and that property br
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Isn't there a galactic north pole too? Doesn't the galaxy have a North/South property of it's own? The earth fits inside the galaxy and each has it's own North pole. I don't see what's wrong with the idea that there might be something larger than the universe with it's own time property?
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It is the secret fear of the outcome of this judgment that causes humans with feigned certainty to deny the existence of God.
Wowee, so I don't believe in your religion because I believe in your religion. Thanks for the tip.
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Why is it so hard for people to understand that there is no "before the big bang"? Time was created at the big bang. There is no "before time began". Before time, there is no before. A bit like there was no spelling bee champion 65 million years ago. Maybe very little like that. Or maybe a bit like asking what is west of the moon. Hmmm... ok, very little like that, too. How about like asking at what date 13 became a prime number? Yes, more like that. You get the gist. Time is part of our universe. The big bang created the universe, space and time together.
If there was no big bang, then maybe there was something before whatever was then. But if there was a big bang, there was nothing before that.
So basically what you're saying is that in the beginning, there was nothing, which exploded.
And you wonder why people have a hard time grasping current big bang theory. :-)
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I'm saying there is nothing "before" a space-time singularity...
But, yes, I certainly don't grasp it.
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So basically what you're saying is that in the beginning, there was nothing, which exploded.
AIUT, there was dimensionless energy. No length (1D), width (2D), depth (3D), or time (4D). Then somebody exec'ed our universe.
People who understand math can show that time loops back on itself as it approaches time zero. Hawking explains this far better than I could.
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Our language relates to the universe we live in so all we have is words like "before" whether we are talking about time or a causally related chain of states. For us they are the same thing.
You may be right about time as we know it not existing until the big bang (and I say "may" on purpose, your statement was rather definitive for something that is really on the edge of our theory and
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You are right. It could be that it is more like a question about what could have caused the big bang, or why did the big bang happen. Or if there was something that could effect HOW the big bang happened.
Even then, causality and time are so closely related....
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I'm pretty sure what happened before the big bang is similar to what will happen after eternity.
Go north from the North Pole (Score:3, Insightful)
A simpler analogy would be to try to go north from the North Pole.
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Yes! That is much better.
One good analogy is much better than three bad ones.
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why is it so hard for you to understand there are many models of the universe, there are those that have events before the big bang, including an endless sequence of big bangs.
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why is it so hard for you to understand there are many models of the universe, there are those that have events before the big bang, including an endless sequence of big bangs.
Endless does not necessarily imply no beginning.
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you're right, and that would imply more models,,,
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Prove it.
Oh, wait, thats part of what they are trying to do isn't it?
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Why not? I can learn so much if I do.
"One may say that time had a beginning at the big bang, in the sense that earlier times simply would not be defined."
[Stephen Hawking, A Brief History of Time (New York: Bantam, 1988), pp. 8-9.]
Obviously, taken out of context.
But, in this "hammer time" (I never heard that phrase), which direction would an egg break to little pieces? Which direction would entropy increase? Is there an answer to this, otherwise, I have a hard time telling what is before, and what is after.
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They're probably mean hammer time, the time that our time is embedded in.
Stop. Hammer time?
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Doooyaaah doooooyaaaahh dooooyaaaah!
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and then who created the guy that created "god".... etc.
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[If people where commenting that I don't know what I'm talking about before, now I really am just going wild - but hey, this IS /.]
Since time is part of the universe, the universe did not start to exist when time began. Existence of the universe and time have nothing to do with one another.
My personal view is that you can think of many many possible universes. (and there are even more you can't think of). Of all these, only ours seems to exist. Why do we think this one does exist, and the other ones we aren
WAP? (Score:2)
we must be prepared to take account of the fact that our location in the universe is necessarily privileged to the extent of being compatible with our existence as observers
http://en.wikipedia.org/wiki/Anthropic_principle [wikipedia.org]
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In soviet russia, moon rabbit measures you!
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The cosmic microwave background is the residual heat left over from the Big Bang event. It was discovered quite by accident (in the 60's or 70's I believe) by Bell Labs, who were trying to figure out where the interference in their communication satellite transmissions were coming from. Its existence had already been conjectured to exist (by Edwin Hubble himself, if memory serves).