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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. "
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.
Just a small correction: a megaparsec is 3.26 million light years, not 3.26 billion.
De gustibus et coloribus non est disputandum
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
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
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.)
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?
Socks. A whole lot of non-matching socks..
And pens.
And.. uhm... Jimmy Hoffa.
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...
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!
No; after disappearing down the back of the sofa/into the depths of the washing machine/through the lining of your coat pocket, those things actually appear as antisocks and antipens in a parallel universe. Down the back of some sofa in some universe there must be a fortune in anticoins.
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.
Leading theory now goes that there is no edge - if you were to fly in one direction, you'd eventualy gotten to the place you started from, similarly to traveling around the earth and ending up in the same place. In case of earth, we're dealing with space that seems infinite in 2 dimensions but is curved in 3d dimension while universe is continuous in 3-d but is curved in 4th D (I'm not totally sure about this point though). It all comes down to universe being finite in space but having no edges.
- Rainy-Day
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.
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
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
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
...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.
...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
All motion is relative, so sayeth Albert Einstein. As such, what we measure is the rate at which objects are moving away from us, as observed by us.
If a galaxy is seen to be moving away from us at 1000 km/s, an observer halfway between that galaxy and ours would see both of them receding at ~500 km/s (approximately, the effects of special relativity are quite small at such paltry speeds).
To use your analogy, suppose you were sitting at the exact point someone hit the water with the stone. Both ants would be moving away from you at the speed of the wave (assuming they are on miniature surfboards). Each ant, in his own "stationary" reference frame, would see you moving
away at the speed of the wave, and would see the other ant moving away at twice the wave speed.
This is, of course, a classical example. If the speeds are relativistic, the expression is no longer v_r = v_1 + v_2, rather v_r = (v_1 + v_2) / (1 + v_1*v_2/c^2), limiting the relative velocity to the speed of light, c.
Eric
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!
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
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.
- None can love freedom heartily, but good men; the rest love not freedom, but license. -- John Milton
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?
Y'know, if some members of any other religion believed in a young universe and posted as such here, I doubt it would have been modded down to minus 1 and ridiculed. If you diss any other minority (Christianity is a minority faith in this country (UK), at any rate), you rightly get lambasted for prejudice. If you diss Christianity, or abuse the name of the Christian deity, no-one gives a monkeys. It's an utterly outrageous situation IMHO.
Have some respect the beliefs of others. You may find them daft, illogical, or downright ludicrous, and that's your right, but don't criticize them or ridicule the person because of his beliefs. You wouldn't behave in a racist or sexist manner in a public forum such as this (at least, I hope you wouldn't), so you shouldn't behave in a "beliefist" manner either.
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