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Age of Universe Derived
HaeMaker writes "The age of the universe has been calculated to be 12 Billion years +/- 10%, and the Hubble Constant (the rate at which the universe is expanding), is 70km/s/Mparsec.... or in other words, for every Megaparsec (3.26 Billion Light Years) an object is away from us it is moving 70km/s away from us. So, if a galaxy is 2 megaparsecs away, it is moving at a speed of 140km/s away from us.
Here is NASA on the subject. "
When people talk about the edge of the universe (and sometimes qualify it by saying 'observable universe'), they are referring to the 'shell' from which a photon of light, if it started travelling at the start of the universe, would have just reached us. In essence, it provides a limit to what we can see or be affected by
If you travel indefinitely in one particular direction, then you will obviously not meet the edge, since (naively) to stop it 'pulling away' you must travel at the speed of light (Since that is the speed at which it is receeding)
If I recall, space (if closed) can be thought of as an expanding 4D hypersphere
John_Chalisque
I heard recently about theories concerning
'tension' of space -- and indications that,
to some degree, Einstein was right to add
the cosmological constant.
John_Chalisque
Every point in Universe is the former center of Universe.
-- $SIGNATURE
Does anyone know if all these old objects are observed in one area of the sky? Or are they sprinkled about? And if they are sprinkled about, what is the greatest distance between any two of these old buggers?
My logic would tell me that we are seeing them now at the location where they were x billion years ago. And if we are seeing them as they were shortly after the BB, shouldn't they be fairly closely packed?
This debate is not over by a long shot. Hubble's resolution ability is too inferior to accurately gauge h0. Since they have been surveying many distant galaxies using many different techniques to determine their distances, one slight mistake in assumptions could throw their calculations off. In next months American Astronomical Journal there will be research results printed from SN1998b which gauged H0 to be 64 m/sec/Mpc. Although this still gives the age of the universe as being around 12 billion years old, it should lay to rest this argument. The technique of using Cepheid variables and a Supernova type Ia in the cosmological distance ladder is agreed by everyone in the astro community as being the most reliable method of determining the Universe's age. I'm putting a paper online within the next couple of days if anyone is interested in reading it. Email kevlar@mail-me.com for more information.
~~Kev
But think for a second: There is a universal "background radiation" everywhere you look in the universe, as empty space has a temp. of about 3 K. (There's energy everywhere, in other words.) Now everybody knows E=mc^2, so it's easy to see that m=E/c^2. Photons have zero rest mass, but they're never at rest, and so have a little tiny bit of mass...
Empty space radiating at 3 K doesn't correspond to a lot of energy, of course, but there's a heck of a lot of space out there, all of it with some energy, and hence with some mass. Could that be where the "dark matter" has gotten to?
(Yeah, I know this is slightly off-topic, but I thought it might be of interest. My physics is probably completely screwed up, too...)
Give a monkey a brain and he'll swear he's the center of the universe.
I forgot about "Flamebait". I lose.
So if when the radius of the universe increases by a factor of two, the total area of the universe increases by a factor of 4, what is the mass of the universe? Can we calculate this?
Even though the universe is expanding (according to theory), as a whole it is stationary w.r.t. itself, so it does make sense to ask the question "how old is it?"
I think.
g
Admit nothing, deny everything and make counter-accusations.
Here's some links to check out:
sci.astro Cosmology FAQ
Ned Wright's Cosmology Tutorial
The above question is discussed, among other things.
We're going down, in a spiral to the ground
Thanks in advance to anybody who knows...
-----BEGIN ANNOYING SIG BLOCK-----
Evan
rooooar
The last part of the first paragraph should read open, Omega 1.
(When will I learn to use the preview button?)
Several current theories hold that the universe expanded for a bit at less than light speed, then underwent superluminal expansion (inflation) objects at the 'edges' of the universe lost contact. This is based on the fact that objects whose light is just reaching Earth from opposite directions are similar in nature even though neither object can yet 'see' the other. They MUST have been able to see each other in the past in order to be uniform.
In some of those models ('Cosmic Foam'), some parts are still experiancing inflation but we cannot see them (since they are moving away from us faster than light).
Personal musings: Interestingly, under that theory, to leave our local (but very large) bubble where inflation is done, would be like entering the event horizon of a black hole. It is a one way trip because you are now receeding from that boundary faster than light. For the same reason, you have disappeared from the perspective of an observer inside the bubble.
Scientific American had several good articles on all of this 2 or 3 issues ago.
Just a small correction: a megaparsec is 3.26 million light years, not 3.26 billion.
De gustibus et coloribus non est disputandum
Responding to those parts of your comment that I can actually parse: Quasars are very distant. Any determination of their age will require using H_0. That's what the Key Project has made a measurement of. It makes no sense to say that the new measurement of H_0 is wrong because computations using it produce results inconsistent with a different value of H_0, but that's what you're doing. Now, it makes more sense to estimate the age of something nearby, which you can do without using H_0, thereby getting a lower bound on the age of the universe in a way independent of cosmological parameters. The classic way to do this is isochrone fitting of globular clusters. You look at a GC near our galaxy, and use stellar models to determine the GC's age based on which stars are still around (massive, bluer, more luminous stars die earlier). Now, first, these methods used to give much different answers, with age(GC) considerably larger than age(Universe). That's bad. But more recent determinations of most quantities typically allow age(GC) age(Universe), with some time for GC's to form, within the errorbars. Putting that aside, there are a few problems with this method anyway: 1) It's been written here at least twice, and I'll make it a third. The HST H_0 Key Project did not measure the age of the universe. They measured H_0. To get t_0, you also need other cosmological parameters. And the difference between t_0 for an empty universe and a flat universe for a given H_0 is considerable, 50%! 2) If your stellar models are wrong, your isochrones that you use to fit GC stellar populations are wrong. Why assume that the GC method is right, and the measurements of H_0 and other parameters are wrong? Hell, they're probably all wrong! Anyway, may I suggest that you drop the flamebait and consider the possibility that the folks who have devoted their life to this science might have an edge over you in this matter? It's pretty presumptuous to stand up and declare work to be wrong when you hardly know anything about it.
If we are using our time frame, how it
it possible to assume that:
1) Our 'inertial time frame' has existed since
the birth of the universe.
2) Our 'inertial time frame' has not in the past,
"sped up" and/or "slowed down" relative to what
is being measured
It seems to me that if you are using our frame of reference, then you are using a rubber ruler
to measure the rest of the universe, because you
don't know how much our ruler has stretched or
shrunk....
die troll.
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havent tehy said before that they have found qasars etc that are >15Bilion years old, so then tell me, did these 15 billion year old objects, that we see as they were 15b years ago, just apear over night? Surely something we see that is 15b, probably took 1-5bilion to form any way.
AND all the shit we see that is 15B is REAL HuGE/BIG so how can we say that smaller shit that we cant see be not there?
I say the universe is infinite age long and stuff outside 15bilion years light range is so dim we cant see it, or that light as it travels disipates so much that its virtualy nothing.
Science is never right, only bending towards reality ever so slowly
I didn't mean to imply that the reasearchers didn't know what they were talking about. What I meant was that because of all the uncertainty in these kinds of calculations..any result should be taken with a grain of salt. At least until all of the variables can be explained and justified 100%.
No one is arguing about Newtons Laws anymore because they have been proven correct. The formulas and constants used in the universal expansion and age calculations still have a long way to go.
Ex-Nt-User
Ex-Nt-User
Maybe there is something 13 billion
light years away that won't be seen
till next year.
It seems that every few years some new group of researchers "discovers/calculates" the age of the universe. And everytime they recalculate it the universe seems to get older by a few billion years. So I would take this latest calculation with a grain of salt, 'cause I'm certain that in a few more years someone is gona claim that it's 13+ billion years old.
Ex-Nt-User
Is there? What is the absolute smallest thing you can think of? Long ago it was likely a piece of dirt. Then maybe an amoeba, an atom, an electron. What is it now? A neutrino? Have you seen inside one to know that it's the smallest particle? Prove to me that there is a limit to how small something can be and I'll be perfectly happy to rescind my theory.
-- First post (by a female living in a state that begins with M and does not end in a vowel with a birthday that falls
According to that math, if an object is at the edge of the universe(roughly 12 billion light years away), it would be moving only about 260km/s away from us. That doesn't seem very fast. I wouldn't even think that any redshift would be detected at that velocity.
The biggest question remaining is just how fast that expansion will be in the future - slowing down or speeding up? This depends on the value of the cosmological constant, a value which is highly contested right now.
In the most common cosmological models, space does not have an edge. It is either infinite in extent (picture a plane) or finite but unbounded (picture the surface of a sphere, you can travel across the surface without ever running off the "edge"). (Of course, space is the 3D analogue of these 2D examples.)
i thought that they became wire coathangers in the bottoms of closets... but i've been out of the theoretical loop for a while.
I was wondering the same thing. Can objects at extreme distances be receding so quickly, that light from them is not fast enough to reach us ? If the light is red-shifted to far, does the frequescy become zero and the wavelength become infinite ?
Does anyone know if all these old objects are observed in one area of the sky?
They are everywhere. Some of them are quite nearby, in fact. There are globular clusters orbiting the Milky Way that are thought to be about 12 gigayears old. That was one of the problems with the previous estimates - there were globs that were older than the universe according to the estimates. I think the new age estimates are more in line.
My logic would tell me that we are seeing them now at the location where they were x billion years ago. And if we are seeing them as they were shortly after the BB, shouldn't they be fairly closely packed?
Not sure why you think this should be so. If two distant objects were on opposite 'sides' of the universe (from our point of view) when light left them 12 billion years ago, wouldn't they still appear to be on opposite sides of the universe today? In any case, I think they are distributed pretty uniformly.
g
Admit nothing, deny everything and make counter-accusations.
A better analogy is a ball of bread dough with raisins in it (mmmm.. cinnimon raisin :)
anyway... as the bread cooks, it expands, carrying the raisins away from each other (each raisin moves away from every other raisin)
But the raisins themselves don't expand (like a dot on a balloon would) they simply get carried into the new space, like galaxies and clusters of galaxies.
if you think of three raisins, one near the center, one half way out, and one on the edge, you see how hubble's constant works.
The inner raisin sees the middle one (1 distance unit away) moving by however much the dough between them expands (say 1 velocity unit), then the outer one by say 2 velocity units (at 2 distance units away).
Then you would have hubble's constant of 1 velocity unit per 1 distance unit. To put it in terms of actual units, 1 km/s per 1 Mpc.
Now think in terms of the middle or outer raisin. The middle raisin sees each of the other two raisins moving away from it at 1 velocity unit, and they are each 1 distance unit away. So the middle raisin measures the same value for hubble's constant! (same for the outer raisin).
Thus it doesn't matter where we are in the universe when measuring hubble's constant.
Doug
Venn ist das nurnstuck git und Slotermeyer? Ya! Beigerhund das oder die Flipperwaldt gersput!
Agreed ... and where is the news anyway. Minor note, the Hubble Constant is one of the most often changed constant I know of 8)
...
Numbers around 10 to 20 billion, later 10 to 15 billion years are really old. Adding to that the Big Bang is still not the final word, the whole notion of age might end in not making sense at all. Might even be not even time as we "know" it now, though try to get an answer what time is
You 32-bit luddites and your prophecies of doom.
Go 64 bits. A LITTLE more time to think.
Eagles may soar, but weasels don't get sucked into jet engines.
Here's a couple of cool ways of looking at this:
1. Where are we? Are we at the "edge"? The "center"? Since all galaxies (except a couple of nearby ones) are moving away from us, maybe we're at the center. Maybe it's like the old "spots on a balloon" example: to each spot on an expanding balloon, everyone is moving away.
2. Let's say we're at the center. The age of the Universe is 12 billion years. That means we can see 12 billion light-years in all directions, which we take as the "edge". Let's say we travel at the speed of light so we can reach the edge as fast as possible. Once we go 12 billion light-years, we stop and look around. Whoops! It's been 12 billion years! The "edge" has moved! The Universe is much bigger now.
3. Let's say we're at the center again. We can see 12 billion light-years in all directions. However, the light from the "edge" is 12 billion years old, the age of the Universe. We're seeing the hydrogen from the Big Bang, the center of it all, in all directions. Does this mean that the "edge" is actually the original center of all things?
Fun with cosmology.
Science sure is bunk! Good thing we had religion to cure tuberculosis, create pennicilan, increase crop yeilds a hundred fold, utilize electricity, and invent transistors! Without religion, we'd be burning people like Bruno at the stake for saying crazy things like the stars are actually suns like our own and imprissoning Galileo for saying stupid stuff like the earth isn't at the center of the Universe.
God is bunk. Get a dose of reality.
As an xhausmate would say, kinda sorta not really.
... IOW, the distance between points of interest is getting greater.
The problem is that _everything_ used to be in the center of the universe --- that's, by definition, what it means for the universe to be expanding. So, from the point of view of all points in the universe, it looks like the rest of the universe is accelerating away
So everyone thinks they used to be the center of the universe, and they're right.
well it is provable if not in a practical way...if it IS only matter that is expanding,, then you can send a lightwave back to yourself at a certain wavelength, it should be smaller when it comes back (shorter wavelength, smaller amplitude)...at least one would think so, and youd have to recieve the lightwave a years after you sent it for it to be noticeable in any way :P
"There is no spoon" - Neo, The Matrix
1 megaparsec = 1 million parsecs, not 1 billion.
I give myself a headache thinking about this stuff.
I guess my argument goes something like this: these things are 12 Byr old and the light we see today has been on the road for 12 Byr. Therefore, we are seeing them as (_and where_) they were 12 Byr ago. Since we are also seeing them "shortly" after the Big Bang, and since that originated at some unknown but single point, shouldn't they be a lot closer with respect to each other?
Or is it proposed that the BB threw this material nearly instantaneously to the locations seen today and only then did it organize into the assemblies that we know?
Working from the expanding balloon analogy, I would expect that we would see the universe more as a snowcone, with us somewhere in the middle of the hemisphere protruding above the rim of the cone. All visible things are within the confines of the cone, with things _outside_ the cone (but still in the universe) not having had sufficient time for their light to reach us as yet.
Yes... I think the drugs are kicking now!
-J
It is the lower limit! Some stars tell us that the universe is 18 billion years old! Either way, such a problem has too many factors unaccounted for which is why physicists usually accept 10-20 billion years old and leave it at that!
Use the (admittedly overused) expanding balloon example. You're on a balloon, on the surface. Someone starst blowing up the balloon. All the other points on the balloon start moving away from you. The points right next to you are moving away from you slowly, but the point on the far side of the balloon are moving away really fast (as fast as the diameter is growing). The universe is something like that (only a tad bit more complicated) So yeah, it actually is moving away from you. And yes, there is a doppler shift.
Then again, every time I mention anything related to physics on slashdot, I'm wrong, so who knows.
Has anyone ever wondered what's at the edge of the universe? Is it more space, or is there just nothing. What is nothing... I would define space as nothing, but if the universe has a set size, what's beyone the edge?
The 3K microwave backgroung radiation; the residual radiation from the 'bin bang' that created the universe. It's very uniform in the extreme and we are moving through it and so it appears slightly red-shifted in one direction, and blue-shifted in the opposite direction. If the CBR is used as a reference frame, will it not appear the same to anyone, anywhere in the universe? If so, does a workable, absolute frame of reference impinge on Einstein's theories at all?
Here's a quote from the article (no joke):
"Alternatively, the universe is pervaded by a mysterious 'dark force' pushing the galaxies farther apart, in which case the Hubble measurements point to an even older universe."
Damn that Darth Vader...
Is stuff that's further away actually going faster, or is it doppler/red shifting? or, to us mere mortals would it appear to go even faster?
It is quite interesting how this long and rancourous debate over the Hubble constant highlights the still non-zero tendency of ideology to intrude into science. For many years their were two main camps of astronomers working on this problem. One camp invariably found a value of around 50 km/s/Mpc while the other group always seemed to come up with 100 km/s/Mpc. The real howler was in the uncertainties which were usually quoted as +/- 5 or so. It doesn't take a supergenius to realize that something was not quite right here. Thankfully, this somewhat embarrassing rift in astronomy history appears to be closing due to the featured work of a third group headed by Wendy Freedman. Eventually science self-corrects for ideology, and therein lies the secret for its progress.
Probably the most amusing aspect of this history is that for all these years the number quoted in the textbooks was usually 75km/s/Mpc. Not because a large number of measurements yielded this value, but because it represented a compromise between the 50 and 100 camps. Turns out that number wasn't far off after all!
There is a difference between holding a belief, and having a belief this is just downright ludicrous. The belief that the world is less than 10,000 years old is rediculous to put it mildly. There is no indepedant evidence to suggest the world is that age, so only Christian fundamentalist wacko's hold it, despite the tremendous evidence that contradicts it. They disrupt science classes and by shouting out "WERE YOU THERE???" in discussions about evolution and such. They are clearly off their collective rocker and anybody that has given it any thought knows this to be true.
Some of your ideas are interesting--especially the idea of a kind of 'event horizon' for our reality, but I think your initial supposition is flawed:
Just because matter drawn into a black hole reaches 'c' at the event horizon doesn't mean it would stay fixed at the event horizon. It would continue to fall towards the center at the speed of light--it just wouldn't accelerate any faster.
So you wouldn't have a shell of matter in the shape of the event horizon sphere.
There is a flaw in your thinking. It's not *really* the galaxy that is moving, but rather the space between the observer and the object which is expanding.. so if all space is expanding at a constant rate (which it is), objects appear to be moving away from us at a rate determined by the amount of space between us.
You may want to check out a message I posted a bit higher up which may help you with the balloon analogy (uses bread and raisins).
Doug
Venn ist das nurnstuck git und Slotermeyer? Ya! Beigerhund das oder die Flipperwaldt gersput!
Actually, antimatter has been made in EXCEEDINGLY small amounts in labs. It's just an atom where the protons have been given a (-) charge and the electrons have been given a (+) charge. Deceptively simple, no?
-Andy Martin
-Andy Martin
If y'all don't like me, blow me.
"Nothing 's going to change my world. Nothin 's going to change my world..."
BANG! Lennon was shot and killed.
I think all of this scientific time estimation stuff is kinda funny, because all of it is based on the assumption that time is a linear constant and that it even exists at all :)
Einstein's theories of relativity have gotten support by these same people to say that time is not a linear, but a relative value (even found support of this on the humble earth with fast airplanes).
I'll let other posters battle about time existing...
"That the speed of light is constant (which I have concerns that it is not (Hey it can be turned, twistes and brought to a halt by massive objects.) "
No, the light never stops or changes speed, even when it is swallowed up by a black hole. The space is curved by gravitation. In the case of a black hole, the space is infinitely curved allowing light to travel directly into it without ever reaching the center.
I respect the weight of NASA. It is a great institution that gave a large contribution to present human knowledge. However I cannot respect its tendency to make History out of some pieces of dust.
The so-called "Age of the Universe" is something I would call rather childish. At least, in the way they show the public these things.
Maybe we can determine that such metaformations such as our "Universe" could carry an age. However we must look at two major problems when we face such things.
We don't know all factors that determined the formation of the "Universe". Recent Hubble discoveries even had risen a lot of questions on whether old ideas or hypotesis are correct at all. Not long ago there was a little squirmish about Hubble's constant itself. Not to count on such things as finiding galaxies near the "edge" of the Universe.
Do we know the Universe? Aren't we missing anything? Up to the last century many people were convinced that the World and subsequently the Universe were not older than 6000 years. In fact this belief, based mostly on the human experience of something called "civilization", was proved wrong. Today this same civilization possesses a wider reaching eye and manages to see things supposedely 12 billion years old. However beyond that "eye" there might be a lot more. Besides it seems that this "eye" possesses some short-sightness due of a strong belief that it can't be wrong.
Not with light anyway. 'Our ' universe, by definition is only as big as the set of things that we can influence or that can influence us. I'm getting a bit out of line here, but the 'universe' might be bigger than the stuff that we can see, but it doesn't matter. By see, I mean without technological limitation. IOW, with the Hubble we can see farther than ever before, but there will be an end, some distance that we will not be able to see beyond no matter big a scope we build. That distance is effectively the end of our/the universe. The effective universe is limited to that we can see, or can see us. There is simply no way for anything beyond that radius, the distance that light has travelled since the start of the universe, to affect us. So, if there is anything 'out there' it really doesn't matter(pun semi-intended).
Good judgement comes from experience, and experience comes from bad judgement.
- W. Wriston, former Citibank CEO
I would imagine myself inside a
large box.
I would start to shrink while the
box would get larger.
No matter how small I got or how
much the box grew, I was still in that box.
Many cosmologists believe that during the first few fractions of a second the universe DID expand faster than the speed of light. However, it was spacetime itself that was expanding, not that matter was travelling faster than the speed of light. They call this superluminal expansion, and it's a rather commonly held belief. I don't remember the numbers, but it's thought that in the first few milliseconds after the 'big bang' the universe expanded to about 80% of its present size (or so).
That's why cosmoligists talk about 'horizons' of the universe that are visible from Earth. As time goes onwards we can see more and more of the universe that was previously invisible because light from that location would have taken more time to travel to Earth than the age of the universe.
However, it's been years since I've taken that graduate cosmology class, and I barely understood the stuff back then...
(A tip to the ambitious - don't take a grad physics cosmology class unless you've undertaken a detailed study of general relativity. It's much less painful that way).
D. Keith Higgs
CWRU. Kelvin Smith Library
My office has been taken over by iPod people.
The Earth and universe are less than 15,000 years old, the Earth is the center of the universe, the sun revolves around it once per day, and Darwin is/was the anti-Christ.
10 PRINT CHR$(205.5+RND(1)); : GOTO 10
And I almost don't believe the rest of the universe has the same time frame as us.
-- insomniac --
Could someone briefly explain to me why the result of the "big bang" and expansion of galaxies from it is considered the span of the entire universe? I was sort of under the impression that the universe is goes infinitely in all directions, so doesn't that kind of guarantee that there's more matter doing its thing elsewhere in this big ol' vacuum, far beyond "the edge" as some of you call it? I think I'm fundamentally misunderstanding the accepted theories, I just can't grasp the concept that "there are so and so billion stars, this many galaxies, and that's it."
I assure you that it's the media. Wendy Freedman presented some of this Key Project's results at Caltech a few weeks ago, and while it was an interesting colloquium, nobody was running around thinking anything was more settled than it was the day before. You can be assured that in almost all cases, the scientific community (including the authors of a result) are a lot more conservative than the media in reporting it.
I also find it alarming that almost everywhere that I've seen the media report this result, it's phrased as "the age of the universe". They Key Project members produced a new measurement of the Hubble constant; the age of the universe requires knowing both the Hubble constant and other cosmological parameters which this project was not trying to measure, AFAIK.
I don't think the bible can tell me what is all in a cubic foot of soil. Ego or not, perhaps science is no more based on ego than religion is based on theological imperialism.
I'm sure "SlashdotMedia" will improve on all the wonders that Dice Holdings blessed us all with
Doppler/Red shifting is always caused by a difference in speed. So the further away an object from earth, the faster it moves relative to earth.
Red shifting can also be caused by gravity. As light travels up through a gravity well, it gets red shifted by the time dilation. From the perspective of a distant observer, time slows down inside a gravity well.
Your other question was handled by the balloon analogy, but I'd like to add something. This type of misunderstanding arises from assuming that all the stuff in the universe was once contained in a very tiny volume and then exploded into a previously empty universe. This is not what the big bang theory states. It states that the universe itself was contained in a tiny volume. It's a subtle but important difference.
g
Admit nothing, deny everything and make counter-accusations.
I hate to sound self centered but as far as I can tell the universe came into being some time around 3rd march 1970 (my birthday).
Comment removed based on user account deletion
Refer back to the "balloon" analogy. The center of the ballon universe is not on the surface of the balloon, its the center of the balloon. So none of the dots on the ballon can be at the center of the universe.
.1 cm farther, the other one moves .5 cm (due to expansion) .1cm/sec, the farther dot's velocity is .5cm/s, even though the ballon expanded uniformly in all regions of its surface.
From the point of view of a dot on the balloon, the farther away another dot is on the balloon, the faster it is expanding away from you.
Here's the math:
*over 1 second, the ballon expands by 10%
*there's one dot 1 cm away from you, and another 5 cm away from you
*over that one sec., the closer dot moves
*The closer dot's velocity away from you is
Hope that helps. Actually, I hope that's even accurate (long time since college). Please correct me as needed.
Who says dolphins aren't intellignet - they spend their whole lives playing around in the ocean, never have to pay taxes, go to school or buy food. I'd say that was a pretty decent way to live.
Every cosmology class that discusses the formation of black holes and the creation of the universe overlooks one very glaring inconsistancy. If all matter the universe was in the same place at its start, how did it escape from this state? Even Hawking's theory of black holes evaporating where virtual particle/anti-particle pairs form near the event horizon is a slow process and nothing at all like a 'big bang'. The only way out is to say that the universe itself is a black hole (in some larger meta-universe), thus it did not escape the black-hole state. We're all still within the black-hole that is the universe.
Stating that H0 is 70 would enrage many scientists that happen not to be in the "high H0" camp. Recent optical data (and radio astronomical data here in Cambridge) suggest H0 to be 50 and 42 (yes, the meaning of it all!) respectively. The "high H0" camp are actually losing ground, and to understand the disparity you have to realise that many people have their careers at stake on the value of H0.
H0 is being measured all the time, this is just one result, which is not even typical.
D.
Newton's Laws are NOT correct. They have been basically revamped with relativity and quantum mechanics. Essentially, things change as you either go very fast, or become very small. However, at normal 'everyday' size, speed, and time scales, they make a good approximation. For instance, NASA uses Newtonian physics more 99.999% of its orbital calculations. However, ask any of the physicists at FermiLab or CERN, and they just thrown Newton right out the window.
Of course you are correct in asserting that there are many unknowns here which are being assumed. However, relativity has a first order approximation as Newtonian physics, and similarily the cosmologists are using what they know about GR to deduce an estimate about the age of the universe. We still don't know the physics of the big bang and black holes, they're currently mathematical singularities (ie, there are zero's in the denominator).
Don't forget the Big Bang Burger Bar. If you can watch the Big Bang while you eat, it must have existed before the Universe in the Great Whatzit that was there before the Universe, and is currently being pushed back by the edge of the Universe.
--
"Outlook not so good." That magic 8-ball knows everything! I'll ask about Exchange Server next.
Doesn't the theory of reletivity state that certain constants (specifically the speed of light, and its associated limits) must remain the same regardless of the position of the observer and the object being observed? .9 of the speed of light (measured by an outside observer), the closing speed (measured by the rider) would NOT be 1.8 times lightspeed due to the slowing of time.
The example that I have always seen used is that if two poeple were riding motorcycles, each travelling at
Or is the direction (approaching vs. departing) of the two objects also a factor here?
--Paul
McFly777
- - -
"What do people mean when they say the computer went down on them?" -Marilyn Pittman
The hubble constant would cause you to expect this to mean that at points the Universe would expand at greater than the speed of light.
What am I missing?
The Edge of the Universe, if it Exists [Wich I believe it does not] would be either invisible, or a Bright white light.
:)
If it is in fact a bright white light, We will all Die someday when we look up to see the sky is Pure White, Then we fry. So I vote for the first one [wich seems to me, the more logical]
But before we go about talking about "The Edge" we must first define it. Space is a Vacuum. It is Empty. There is a bit of dust floating around, but that's it. So when you talk about the Edge, Where nothing else exists, Are you talking about where nothing is, currently? Where there are no more Galaxies, nebulas, etc? Beyond that is Dead Space. Vast Emptiness. But then wait- You're their, Light is there, Bang, your definition is ruined, the universe is infinite.
Or are you talking about 'The edge of the Plane' where Nothing does exist, Will exist, can ever exist, Nothing will exist beyond this point.
Well in that case here's whats on the other side: NOTHING. Nothing can be by that definition.
But if nothing Can exist beyond that point, is it an Impenitible feild, that matter would not be able to push through, Or is it a place that Matter would dissapear through. You put a chunk of Naturally Formed gold through, You pull it back, There's only half there. The rest Doesnt exist. More than that, It never existed. You dont notice a change 'Woops, I missed' or more likely, You merely used a peice different from the one you just used. See the Paradox? For the safety of the universe, Dont go around trying.
Some say that Gravity pulls on Time like an Anchor, and as Gravity increases, so does Time. Without time, There is infinity. At the Center of a Black hole, Time itself is so dence that it folds, you can slip between moments (not that you'd really notice, the human brain comprehends time only as linear) But anyway, Maybe we can combine these two Definitions.
Without Time there is infinity. In Infinity, at least as far as human Comprehention goes, There is nothing, and everything, wich is basically what people say would be at the edge of the universe. So beyond the universe is infinity, without time there is infinity, gravity attracts (generates?) time, The Edge of the Universe is therefor just where nothing is. And you can never get there because you're made of Matter. Ha.
Ok, then there's my Theory for The Universe, that says there is no end:
In the Beginning there was no beginning. There was no Time. The Nothingness was as it was and an infinite number of non-existant variables took place. And in that infinity, all probubilities became 1, and so, The most Improbuble thing that wasnt possible happened: The Universe was Made.
(Now I just want to say before Religious guys get on my back, that perhaps in this Swarm of Improbubilities, God was Made as Well. Perhaps you want to define this swarm as God. That's fine, and makes sence to me. It's what you define anyway. God is Infinite, Infinity is Infinite, Please excuse my Twisted logic for perhaps explaining your god into existance)
So anyway, the Universe was Made, and With the Universe Came Time. But the Universe was "Already" made, when this happened. The Creation of the Universe, brought forth time. And because the Universe was made "Before" time, It is Infinite.
I put "Already" and "Before" in quotes, because we're talking about the creation of time. Actually, This all happened in the Same Instant. The universe is Infinite. This also says that all things are possible, and somehow Impossible. It brings in the idea that we may not see all that is there. Is this Theory a Religion? By God I hope not
It's merely a Scientific Theory of why everyone who doesnt believe in anything at all, is wrong.
It also says that we do not neccissarily Exist. So There. =P
"I say you do not Exist. Who are you to Argue against that point?" -- The Bitman
Sorry bub. Won't fly because there is a limit to how small something is.
the hubble constant is only one of the parameters you need to calculate the age of the universe. the overall mass density (commonly expressed as q_0 = mass density/critical density for collapse) and the cosmological constant (if any) are also needed. the 12 billion years is derived assuming the mass density is equal to the critical density for eventual collapse (a flat universe; q_0 = 1) and no cosmological constant. however, we don't really yet know what the values for these other parameters are, even to within a factor of two. current best estimates favor q_0 less than 1 and a nonzero cosmological constant which can result in ages of 15-20 billion years or more for the universe.
the hubble constant is a hard thing to measure right and it's taken decades of work to get it to within 10%. measuring q_0 and the cosmological constant to a similar precision is decades more away, i think.
tim (i'm not a cosmologist, but i play one at work)
hiding in shadows / i hear you coming closer / you will explode soon -- a quake haiku
I know I'm beeing pedantic here, but having a constant which says 'If X is n away, then X is moving at n*k' suggests that as the galaxy moves away it's accelerating.
Either that or it's not a constant.
I know in the big scale of things it will be, but...
Here's something fun to consider.
Suppose you have three galaxies equally spaced in a straight line. Call them A, O and B, with O in the middle. Suppose that these galaxies are far enough apart that galaxies A and B are each receding from O at 75% of the speed of light (c).
How fast is A receding from B?
Did you say 150% of c? Wrong!
Don't forget to take relativity into account. Apparently, the speed is 96% of c. Unfortunately, I forget the formula used to calculate this.
The only thing necessary for the triumph of evil is for good men to do nothing. - Edmund Burke
Unix older than time! Punchcards at 11:00!
--
There is a fine line between stupidity and insanity. I should know, I'm standing on it.
I'm not "dissing" Christianity at all, nor would I begrudge anybody the right to believe whatever they want. What I'm "dissing" is the extreme minority fundamentalist sects (I myself would be considered a Christian) who continually spread lies and attack "the establishment," which they view as a threat to them. The issue is not an unpopular or preposterous belief; the issue is the way that some of them feel the need to lash out at anybody who would question it. If you visited the "Earth Is Not Moving" page, you'd see plenty of references to "The Copernican Lie", attacks on science, and other such inflammatory rhetoric. This goes well beyond a deeply-held belief.
I do respect the beliefs of Christians who believe that the universe is between six and ten thousand years old, much as I respect other viewpoints that I don't agree with (such as the whole abortion issue.) What I do not respect is the methods that their most vocal members use, and the self-righteous manner in which they condemn anybody who dares to disagree with them. When somebody comes out and claims that NASA is leading us down the road to "hellfire and eternal damnation," I reserve the right to consider that to be nutty. And I stand by my assessment. (It doesn't really matter if the above post was a troll or not; I know an individual who actually claims that the scientists at NASA are the spawn of Satan.)
So to the fundamentalists: Believe what you want, but don't attack people for using the brains that they were given.
We're going down, in a spiral to the ground
Certainly estimates keep getting revised; that's what science is about. It's not a sign of bad research, but rather an indicator of a healthy field. Nobody (well, no good scientist) will claim to have definitively found *the* answer to a question; we can only approach that as sets of independent experiments converge on a consistent result. Even when this happens, better theories and better techniques can always bring the old results into question.
Unfortunately, occasionally certain experiments get publicised too much, and out of context; the common person will see these occasional conflicting results and point to them, saying "they obviously don't know what they're talking about!". In fact, it's a much more continuous process than this. Cosmology in particular has dozens of different theories, experimental techniques, statistical techniques for *analyzing* the results of the experiments, et cetera. Dozens, perhaps hundreds of papers are published on various aspects of cosmology (of which the Hubble Constant is merely a touchstone, a good way of comparing diverse experiments) every year, you simply don't see most of them.
-spc
You are of course assuming the universe is finite in size.
If it's infinite, there isn't a center.
Think of the balloon metaphor from earlier.
Now imagine the balloon is infinitely big.
It's hard to visualize.
He can ridicule anybody's beliefs if he want to.
Free speach allows him to ridicule anybody he wants to, be it athiests, agnostics, christians, budists, hindus, mormons, ect...
He can say what he wants to; you just don't have to listen.
--
Are you ridiculeing his ridiculeing of the christian dude's beliefs.
--
P.S.: I am a Christian.
Maybe someone who knows more about this stuff
could explain this to me:
As best I understand it, time in our universe
is NOT constant. The speed at which you are
traveling changes the rate of times passage
relative to other objects travel at different
speeds (i.e. as one approaches the speed of light,
less time passes for you than someone moving more
slowly.) Also, it is my understanding that local
gravitational conditions change times rate of
passage.
This being the case, and all that stuff their
measuring moving at different speeds under
different gravitational conditions, How can one
say how old the universe is? I would say how
old is it relative to WHAT??? And that assumes
that what you are measuring it relative to has
been maintaining a constant speed and gravity
since the "birth" of the universe. And somehow
the existance of such an object seems unlikely...
Anyway, could anyone correct me if I'm
misunderstanding something here?
...is that the time (and thus the universe) began on January 1, 1970. It will end in 2038. Don't believe the non-Unix pseudoscience.
Seems like a lot of the time the Universe is on really good acid.
...that when you fly through it, turns certain people's eyes silver and gives them superhuman telekinetic powers.
/galaxy/, not the universe.
No, wait, - that's the edge of the
I think there's a restaurant at the edge of the universe though.
Ahh, need coffee. Brain not work yet.
DG
Actually, there are some theories that the universe isn't expanding at all. I'm not saying that they're right, but here is the basic idea: According the QED, light does not always travel at the speed of light, it is just most likely to travel at the speed of light, and averages out to travelling at the speed of light. In normal circumstances, it travels at the speed of light as well as we can measure it. However, when dealing with extreme distances, such as the distances between galaxies, these slight variations in the speed of light add up, and the light wave spreads out. This actually increases the wavelength of the light, and causes the doppler shift which has been interpreted as meaning the universe is expanding. Isn't it interesting that the universe is supposed to be expanding faster further away? Maybe this is just the result of lightwaves stretching more over greater distances?
I am not an idiot. Please use my name to email me.
"That's right, I'm quoting myself."
-Upsilon
I don't know if it's popular or not, but the steady-state theory says that space is constantly being created between the galaxies, explaining the expansion... Although this was largely disproved by radio dating. *shrug*
This example seems to assume that the earth (or some point in space) is fixed. If, in fact, all other points are moving away from it, wouldn't that mean that all points are moving away from eachother at rate between (just over 0) and 2 times 70km/s/Mparsec?
To use a 2d example, if I throw a stone into a lake, and ants were to surf the resulting wave: 2 of the ants, side by side, would be moving away from eachother at a slow rate. However, 2 ants on opposite sides of the wave source would be moving away from eachother at a rate that is twice the speed of the wave.
So, is this 70/km/s/Mparsec rate the speed of the wave, or am I totally off-base here.
-avi
...does make a difference, but not as much or the way that you might imagine.
The stick that is used to measure the universe is light, as in the speed of. When doing relativity calculations, doppler shifts, gravity effects or whatever, all speeds are referenced to the speed of light. The very words "light year" as defined as the distance that light travels in a year, is relative. Anyway, when the cosmologists talk about the age of the universe, they could just as well be talking about the size of the universe, as in "It's gotta be at least 12B years old 'cause we can see stuff that is 12B light years away!".
Relativity effects will cause the appearance of the universe to change, but it will not change it's apparent size/therefore age. IOW, lusers in those far away galaxies will look at us and say "Wow, they are hauling ass away from us, they must be at 12Bly away, so the U must be at least 12By old!". So they see us differently from the way we see ourselves, yet we appear to be just as far away from them as they appear to be from us.
Good judgement comes from experience, and experience comes from bad judgement.
- W. Wriston, former Citibank CEO
The objects themselves are distributed randomly, but for objects outside our own galaxy there is a catch.
The gas and dust which make up the spiral arms of our own galaxy obscures our vision.
We can only really see interstellar objects up and down out of our galactic plane.
I'm not sure about the actual number of degrees which are obscured, but I believe its somewhere in the range 15-45 degrees
Doug
Venn ist das nurnstuck git und Slotermeyer? Ya! Beigerhund das oder die Flipperwaldt gersput!
This is exactly right. We can't see the entire Universe, we can only see our patch (the region within the so-called `Hubble radius', which is defined much the way you've done the calculation above.) Another way of thinking of this is that if, at the birth of the Universe, a protogalaxy (which is now a few Gpc away) shot a photon at us, the current age of the universe hasn't been enough time for the photon to hit us yet; so, we can't see that galaxy yet. This is an extremely important point for understanding why another question, homogeneity, puzzles cosmologists so. The bits of universe that are just barely within our horizon now but in opposite directions are not yet in each others horizon; so they haven't had any chance to interact with each other yet at all, much less come to any sort of equilibrium. However, we can see both bits -- and they look exactly the same. The CMB from both directions is identical. How on earth did THAT happen? Is it just co-incidence that all these completely so-far unconnected bits of universe were at exactly the same temperature?
"Read
the bible and get a girlfriend."
Wow! Now I'm really confused. If I read the bible, will I really get a girlfriend ? Does she come with the bible, or separately ? Does the bible explain how to get a girlfriend, provide URLs for girlfriends, etc. ?
the flow of time is ALWAYS linear (going forward) just not constant (relativity) Also, time just changes noticably around large gravitational wells (balck holes) or at fast speeds...And for all practical purposes, time exists, as we are temporal creatures...not much you can do about that :P
"There is no spoon" - Neo, The Matrix
Just because matter drawn into a black hole reaches 'c' at the event horizon doesn't mean it would stay fixed at the event horizon. It would continue to fall towards the center at the speed of light--it just wouldn't accelerate any faster.
Actually, the region "inside" the event horizon of a black hole is generally regarded as singular, in the sense that it doesn't satisfy axioms for spacetime upon which general relativity is based. Really, no one knows what happens beyond this boundary; we can only decide behavior at the boundary itself.
-josh
Aren't you dead?
Did you forget to take your Prozac today?
Anyway, my question is this:
We say that the universe is expanding because of the doppler red shift in the light that reaches us from the stars in the outer reaches of the universe. We are basically looking into the past when we are observing the stars in the outer reaches of the universe.
. What if the expansion of the universe is just something that used to happen in the past? Could it be that the expansion of the past has stopped? Maybe the universe is just in steady-state now.
Would welcome the views of all you folks.
No, scientific studies have shown conclusively that noone has ever wondered about that.
No, it is not a coincidence that the age of the universe is 1/H (H=Hubble
Constant). The Hubble Law can be written as:
v = Hd where v=velocity of galaxy, and d=distance of galaxy. this is
also where the funky units for the Hubble Constant come from.
Astronomers like to measure distances in Mpc, so simply multiplying H
by the distance in Mpc gives the velocity in km/s. In actuality it is
much easier to measure the velocity, so astronomers usually divide H by
the velocity to get an idea of the distance.
Here is a quick estimate for the age of the universe: Consider a huge
explosion of galaxies at time t=0. After a while when we look out at the
galaxies, the faster ones will have moved further. A specific galaxy
will have moved:
d = v t where d is the distance, v is the velocity, and t is the time
since the explosion.
This can be rewritten as v = d / t. Now compare this equation to the
Hubble law -- H must equal 1/t, or t (time since explosion) must equal
1/H.
This is the Astro 101 explaination. The correct derivation requires
differential equations and a many assumptions about the flatness and
density of the universe. The correct values for the age of the universe
are:
0 t
t = 2/3H^-1 for a just dense enough universe
2/3H^-1
What always got my goat is that H is called the Hubble constant, but it
changes with time.
-=[doug]=- who has never even pretended to be a cosmologist
"my teacher said that all elements are constant in the universe, but i dont see any neutranian hanging around earth too often, so anybody out there have any idea what the longest scientists have had neutranium for, or rather, have they
even even created it?"
Just a guess here, but might you mean neutronium? If so, you're not, strictly speaking, talking about an element, AFAIK.
Neutronium is produced when the gravitational pressure in a collapsing star is stronger than the electromagnetic repulsion of the electron shells of the atoms. The atoms themselves then collapse into neutrons with no space between them, forming neutronium.
"Read the bible and get a girlfriend."
hmm when did that attitude dominate human history? Oh yea the dark ages..
Take the known mass of the universe (iffy, but still) and calculate the schwartzchild radius for a black hole of that mass. It turns out to be just about the known size of the universe. Now think about matter falling into a black hole. The matter accelerates until it reaches a speed of c which it cannot exceed. This speed is reached at the black hole's event horizon, not at it's 'center'. So black holes are actually a spherical shell of super-dense matter all packed in at the event horizon. And since we all know (I hope) that there is no gravity inside of a uniform hollow shell of matter, the inside of a black hole would be a complete closed off section of space, populated by whatever matter was present inside when the black hole formed, which is now free to safely float about and coalesce to form things like galaxies, stars, planets, you, me, etc. all blissfully unaware and independent of the harsh black hole environment just 'outside' the universe. The outer meta-universe where our black-hole universe exists may itself be a black hole in a meta-meta universe. Can we leave this universe? Maybe but it's doubtful. Our universe is finite in volume but unbounded. You can travel in any direction forever, like a ship sailing in any direction on a world with only ocean and no land. It can sail in any direction endlessly and never reach an 'edge of the world' yet there is still a limited sized ocean over which to sail. The universe is identical to this except that it is finite over 3 dimensions. For you CS types, imagine it as a 3-D array doubly linked in each of the 3 dimensions with the array elements at the 'edges' of the 3-D array cube linked to the element at the opposite end of the cube. Now start anywhere in the cube and follow links in any direction you like, change your direction of travel at any time. You can traverse array elements forever in any of the three dimensions and yet never reach a boundary to a 3-D universe. Our universe, like this, is closed and finite, yet unbounded. This concept is difficult for many to grasp, but I hope these examples help. Back to 'can we escape the universe?' Maybe. If a gravitational disturbance in the meta-universe (say another black hole [universe]) passes close to ours, it can warp spacetime enough to create a link from our universe to another (either the passing black hole or to the meta-universe or both). This link could be temporary or it can expand until our universe actually merges with another. These links are what are called 'wormholes'. Everything I've said here is, of course, all highly speculative may be utter bunk or absolute truth. You decide. Don't flame me. Better yet, bug your physics professors'. They tend to avoid thinking about sensational stuff like this because it has the potential to get them branded as heritics and philosophers by their peers. And this concept of 'proper or right thinking' as definer by their peers, often limits inspiration. Off the wall, or even wrong postulates by people like you and me may make them think of something they would not have ever imagined before. But get 'em thinking. Who knows. Maybe someone, somewhere will make some real discoveries. Most of all, have fun! Science is fun because reality is fun!
Yes - Scott Adams came up with a theory that gravity can be explained by all matter getting progressively bigger. See _The Dilbert Future_. He states that someone else came up with it ages ago, but as it is completely unprovable, dropped it.
yeah, the theory of general relativity :)
when they say "expanding universe", they mean that indeed space itself is expanding. the matter in the universe is just being carried along for the ride. expanding/contracting space is one of the profound predictions of einstein's theory of general relativity, though he didn't believe it at first and added a constant to cancel it out. a few years later when edwin hubble discovered observationally that the universe was expanding, einstein regretted adding the constant and dubbed it his "greatest mistake".
however, there is now evidence that some form of that constant is needed so al might have been right in the first place.
tim
hiding in shadows / i hear you coming closer / you will explode soon -- a quake haiku
If everything is getting further away, we better start our missions to other stars now before they get too far away.....
But this leads to another interesting question: If everything moves away from the original center of the universe, we should measure different amounts of red shifting for equidistant objects, depending on whether they line up with earth and the center of the universe, or whether they are orthogonal to earth. In any event, the distance to earth should get bigger over time, but in the first case faster.
As far as I know, that's not the case, which would mean that earth must be very close to the former center of the universe. Does anyone know more about this?
Under capitalism man exploits man. Under communism it's the other way around.
Aha! But you've forgotten to put a link to this site, which conclusively refutes the Satanic view that the Earth is not the center of the Universe! After you've read through that, buy the book!
I'm fairly certain that the above post is a troll, but I've included these two links to show the truly preposterous nature of creation "science" (that is, start out with a conclusion that must be reached at all costs, and then start looking for observations that could be interpreted as supporting that conclusion, while discarding everything else that does not.)
We're going down, in a spiral to the ground
- None can love freedom heartily, but good men; the rest love not freedom, but license. -- John Milton
Now imagine a 4th dimensional globe (see how easy that is) - that's the universe.
Simple.. just imagine any old globe. Then think about how long its been there.
Found virus... Windows detected.
Remove (Y/N) ? Y
Removed Windows
Rebooting Universe
observations of certain species of stars called "Cepheid" variables were used to obtain these results. these kinds of stars have a well-defined relation between their period and luminosity. so if you can measure how fast they vary, you can derive fairly accurately how intrinsically bright they are. once you know how intrinsically bright they are, you can use that together with how bright you observe them to be to get their distances. do this for a bunch of these stars in a galaxy and you can get a fairly accurate distance to that galaxy. this team did just that for a bunch of galaxies out to much greater distances than was possible from the ground before HST and thus derived the Hubble constant.
so, the Hubble constant was the end and Cepheids were the means.
tim
hiding in shadows / i hear you coming closer / you will explode soon -- a quake haiku
People seem more willilg to accept that the universe can be of finite volume but withoug any physical boundary, yet they continually insist that the universe must have had a 'beginning' or will have an 'end (the big crunch). What if time itself has no beginning and no end but is instead a continuous loop? We may have had this exact discussion 20 billion years ago and again before that and again before that, forever backeard and forever forward. If space can be closed, why not time as well?
Does this only describe the expansion of matter in the universe? Are there any popular theories that say space itself is expanding (or even changing)?
Could be hard, I'd say there's a big risk the universe takes us with it (if it at all ends, that is). But now when you mention it I'm going to change my plan a little.
:) just to see what it's like.
:), being able to switch off for a while when things get dull, harmless drugs and sleep speedup.
It was to live until
1. I get bored, or
2. The universe ends and destroys me too.
(Not taking accidents into account)
Now I think that maybe instead of destroying all copies of me when I get bored I will set the alarm clock to the end of the universe (who knows, I could get a good last meal too
--
How? When I start to grow old and likely to die (or earlier if someone proves it works) I will conserve myself (some kind of freezing sounds doable) in a way that preserves the brain structure and memories. When finally someone can build artificial, electronic brains (or emulators) I will start to live again. And do backups every 'clockcycle' of the emulator to as many safe places at possible. Except (almost) immortality it also gives benefits such as: any kind of body, remote controlling, eating and breathing only when I like to, lightspeed traveling, live quake
Ok, feel free to check my math. I calculated that if the universe were 14839 _million_ light years across, anything at that distance would be moving away from the other side at the speed of light. Of course, we don't have anything strong enough to see this, but could the universe be bigger than we think because things are moving away from us too fast and we can't see them?
According to the story things are moving away at 160,000 MPH for every 3.3 million light years. 160,000 miles is roughly 240 million meters.
240,000,000/3600s = 66,666m/s for every 3.3 million light years. 299,792,458m/s (speed of light in a vaccuum)/66,666m/s = ~14839 million light years across and the two objects are moving away from each other at the speed of light.
All values are approximate except the speed of light (speed of light found at http://physics. nist.gov/cuu/Constants/index.html?/table2.html).
Do really dense people warp space more than others?
Since you really need to understand something before you can create your own, I love reading about stuff like this. 12 billion light years, eh? Not too shabby for a universe.
Someone else asked "what's outside the Universe?" I say, nothing too interesting, there's a bunch more neat stuff inside IMHO. Heck, we haven't even totally explored our own oceans yet. I think our biggest chance (in our lifetimes) of finding sentient life would be down there, it's where we came from after all (if you believe in Nature). Perhaps the things that caused our great ancestors to move onto land has evolved to something......well, just something.
+&x
Last year, two independent groups announced results from extremely distant supernovae that rule out the critical/no comsological constant
universe to very high confidence. Unless there is some as-yet undetected systematic problem with the data, it probably doesn't make sense to keep reporting age estimates based on that universe. See http://www-supernova.lbl.gov
-Rob (who also plays cosmologist at work)
They don't "overlook" it; it's simply not a problem. See the FAQ. The universe isn't a black hole, either; see the other FAQ.
Wait for 5 or 6 years, it will probably change, any idea when we'er gonna decide if we'er a spiral or barred spiral? personally I'd rather know that, just my opinion, and on a side note im posting form computer class, and i came from science my teacher said that all elements are constant in the universe, but i dont see any neutranian hanging around earth too often, so anybody out there have any idea what the longest scientists have had neutranium for, or rather, have they even even created it?
"Read the bible and get a girlfriend."
Is there a one girlfriend per Bible limit ? What if I read the same Bible multiple times ?
that's what i get for leaving my brain at home. when i said q_0, i really meant Omega. Omega = 2*q_0, anyway, so i was only off by a factor of two.
:)
at least i said i wasn't a cosmologist
tim
hiding in shadows / i hear you coming closer / you will explode soon -- a quake haiku
Think of a piece of paper, the paper has an edge.
Now think of a globe, the globe has no edge.
It is thought that the universe is more like a globe than a piece of paper. Now imagine a 4th dimensional globe (see how easy that is) - that's the universe.
Which is all Gravitational theory anyway (and not backed up by experimentation), and suggests that BaronCarlos' point is valid, that there are still too many uncertainties in the equation.
A Parsec is 3.26 Light Years.
Therefore, a Megaparsec is 3.26 Million light years, not 3.26 billion :-)
-- This
A fractal need not be infinite in infinite in volume or area. One only need look at a few of the famous ones to see this. What's more interesting is when a fractal is infinitely self repeating, or semi-self repeating at every level. I haven't seen anything to make me believe that the universe would fit this description, but it's entirely possible. The basic structure of an atom is described with the electrons in "orbits" around the protons and neutrons. That model works for our solar system and our galaxy. Perhaps it generalizes even more.
Adam
I recall reading an article that I think was in Scientific American a while back (sorry folks, no hope of a valid reference here.) where the possibility that the rate of expansion of the universe was increasing was discussed. This was pretty preliminary, but there was at least a bit of a hint of some piece of evidence to suggest this. If this is the case, aside from the fact that we're not currently sure what could be doing this, then the Hubble constant would point to a deciptively short universe
The idea is as follows:
Imagaine a universe caused by a big bang that expands at a constant rate for its entire life. If you were to plot the size of the universe vs. time on an X-Y plot, you would see a wedge starting at the big bang and expanding as time increases. (It might look lie this: ) Now, if the expansion rate has been incrasing, the wedge will curve outward like the cross section of a speaker cone (best visual I could think of). If you were to extrapolate back to the time of the big bang using the expansion rate at the present time (being that at the end of the cone) assuming that it was constant, it would be very fas and you would have a fatter wedge, thus a premature big bang. Basically, you would be using the current (fastest) expansion rate and applying it to the entire life of the universe incorrectly. The inverse is true if the expansion rate is decreasing. Instead of a speaker cone, your universe expansion would look like a champagne flute (the long kind, not the short dealies).
Any measurements of doppler shifts will show the current hubble constant, even though the objects are billoins of light years away and the image we see is that old. The doppler (red) shift we observe is due to the light traveling through the expanding space and that happens over the entire journey of the light. We see the end result of those billoins of years of expansion, so that would not give us a good look at the hubble constant in the past.
If you are interested in this I recommend a book called "The First Trhee Minutes" By Stephen W**** (I forget, it may be Weinberg). It actuall reads well, not like a text book.
I'm no cosmoligist, but your post reminded me of this and, well, once I got rolling down that hill, I just couldn't stop.
Matt (aka BarneyGuarder without his pasword)
And that the Theory of Gravity is Correct. (I refer the reader to an interesting article in the March 1996 issue of Discover.
The article illustrates that the Gravitational Constant ("Big G") is not reliable at all. In fact, some scientists claim to not know how Gravity Works at all.
So take all this with a grain of salt.
(BaronCarlos is an Astrophysics Major at the University of Arizona.)
*Carlos: Exit Stage Right*
"Geeks, Where would you be without them?"
*Carlos: Exit Stage Right*
"Geeks, Where would you be without them?"
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Combining Hubble's constant measurement with estimates for the density of the universe, the team determined that the universe is approximately 12 billion years old.
Obtaining a value for the density of the universe doesn't seem to be a very easy operation, yet they've glossed over it as an obvious point. How would you obtain such a number? It is clear, however, that the value is finite and non-zero. Finite because vacuums exist, non-zero because we exist.
Here's my issue: we have seen consistently that every natural shape is fractal. Consider the cosatilne, the leaves on a tree, broccoli, the shape of a starfish, I could go on forever. Wouldn't it then make sense that the universe is also a fractal?
One way to define a fractal is infinite in the nth dimension while finite in the (n+1)th dimension. Something like an infinitely long line contained in a finite area.
If the universe has a beginning and an end, then it is finite in time. To be fractal it should, therefore be infinite in space. An infinite voulme, given a non-zero density (which is proven very simply by our existence) implies an infinte mass of the universe. That means we can never find the end of the universe because there is no end to the universe!!
-- First post (by a female living in a state that begins with M and does not end in a vowel with a birthday that falls
Just like the question of what is at the center of a black hole, we can only speculate and even then the speculation has very little basis since normal time-space laws don't necessarily apply.
It doesn't matter how time moves.
If time moved backwards the past would have evidence of the future(i.e.:memories).
So the people living in the past would see it as the future.
Wasn't it the cephoid constant or something like that? I read about this on foxnews the other day, and I can't recall any mention of the Hubble constant...
So is it just coincidence that the Hubble constant is about 1 over the age of the universe? (You can get it if you reduce the units km/sec/mpc down to 1/sec.)
Any astrophysicists here?
he emphasis is mine. Is it the media or the scientists that make these proclamations seem so cut and dried, like, "whew! now that's settled!" when in fact, there is so much guesswork, any conclusion is just not certain? I think it's the scientists, but they should know better.
I think a lot of the emphasis is due to the media. I think a lot of scientists realize that these are just one of several data points out there and will admit that.
"When you sit with a nice girl for two hours, it seems like two minutes. When you sit on a hot stove for two minutes, it