Cool video about the Hubble ultra deep field in 3D. A photo of utter blackness taken in "a patch of sky no bigger than a grain of sand held out out arm's length."
The Hubble Ultra Deep Field in 3D
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The Hubble Ultra Deep Field in 3D
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Hubble, Hubble!
Deep, real deep.
Excuse my ignorance, but wouldn't it be somewhat more cost effective and safer to bring the Hubble back to Earth on a return mission(after doing something else) and work on it on earth? I mean, the shuttle seems to do a lot of one-way work, and they could get more value by bringing something back on the return trip.
"in "a patch of sky no bigger than a grain of sand held out out arm's length." = 10,000 Galaxies. That's amazing.
The amount of trips to it would take to bring Hubble back down would probably cost enormous amounts of money and time. The way they did it wasn't cheap by far but it was cheaper.
The research I have done indicates that it would fit into the space shuttle's payload bay. If they have nothing in the bay, it would technically be a 'free' ride home, as the shuttle is already in orbit with the shuttle.
I have a good time on this site:
http://www.galaxyzoo.org/
It is citizen science effort classifying galaxies.
I sort of think of it as a "Hot or Not" for galaxies.
@#3
The Space shuttle is actually really lousy at going into space. Part of the reason that the ISS is in such low orbit is so that the shuttle can reach it easily.
The Hubble is right on the outer edge of where the shuttle can go safely. Part of the reason that NASA isn't thrilled at the thought of Hubble missions is that the margins of error are so so small that far out they do not have the options or extra fuel available on closer missions.
So any mission that goes to the Hubble is going ONLY for the Hubble. And bringing it back means a second mission to put up again. Be much, much cheaper to simply launch a new telescope.
Could it be a weight thing? The hubble probably isn't very light, and the shuttle isn't the most agile of airplanes on the way back down. I think they dump all their left-over fuel in orbit to lighten the downstream load, so I can see them saying "Nah, hubble's too heavy"
Huble Ultra Deep Field is pretty amazing. But every time cosmology or astro-whatever is presented in a video there has got to be some enchanting music in the background (u-u-u-ahhh) that spoils everything.
@ #3 i'm sure if it were that simple, then they would've approached it that way. i would guess it needs a lot of stabilizing work before bringing it down and then the reverse of your assumption would have to be true and they would have to have a scheduled launch with an empty bay to take it back up. due to the cost of the hubble and the precision required to construct it, i'd rather just leave it there.
i mean, you can deliver a three tiered cake to a wedding, but i wouldn't want to rely on it surviving three trips.
see? like I told you, no way there could be other life out there, it's just too damned small.
http://www.youtube.com/watch?v=GmU_q5xrnto
http://www.youtube.com/watch?v=slYpy6ahY4E
It would get shaken apart during re-entry....
Guys, you got just about everything wrong about space telescopes that you could get wrong. Sorry to say that.
1) Building just one Hubble was a waste of money. Most of the money is in development costs. You can build at least 10 of them for two or three times the price of one.
2) Using the Shuttle for anything in the process was a bad idea in every way, except for advertising the Shuttle. A Shuttle launch was never cheaper than $500 million, today we're talking about a billion dollars. An expendable rocket like the Ariane 5 could launch something like Hubble in a much higher, much more usable orbit for $180 million, national pride be damned. (Some astronomer compared doing astrometrics with the Hubble to trying to look at something with a telescope while riding a bicycle and juggling 4 balls ... mostly because of its low orbit that the Shuttle needs to reach it.) That is because the Shuttle has to carry 6 hairless monkeys and 3 huge but unusable engines around in orbit. (It's using special, much smaller, engines once the fuel tank is discarded.)
3) Repairing Hubble, on the ground, in orbit or anywhere, is an even worse idea. In fact they should have sent a replacement and dump that glorified lemon of a telescope as soon as possible. (A 2 lambda spherical aberration that nobody noticed in a multi-billion dollar project - you gotta be kidding. Any random $50 telescope at Walmart will do better than that and the tools needed to find that sort of mistake on a mirror can be bought for even less than $50.) Building and launching a replacement telescope on an expendable rocket would have cost a couple hundred million dollars, the Shuttle mission (that's more than just the launch) cost more than a billion dollars - all that just to proof the manlihood of some space cowboys.
With the money that Hubble cost so far - about 8 to 10 billion dollars - you could have sent 10 to 20 replacements with current and updated hardware into orbit. Having anything between 2 and 5 working telescopes the size of Hubble up there at any given time, doing at least 2 to 5 times as much science.
But who cares about making science when politicians have to proof that something as absurd as the Shuttle somehow still makes sense?
a lunar observatory looks good.
Woah! That animation of the expanding "balloon" Universe and the cosmological redshift is one I did. Wild.
http://www.sonic.net/~rknop/php/astronomy/astromovies/cosmoz2.html
@#13
so it's expensive and not perfect....but when it discovers something as mind-bending as that I just can't bring myself to care. Hubble reminds me of BOB in The Black Hole...battered but loveable
http://www.imdb.com/title/tt0078869/
Anybody know where I can get a copy of the 3d dataset?
For the bubble and or the redshifts?
I'd love to play with some 3d space data involving galaxies or even our local solar system..
^impossible to find probably but kthnx and a million internets to the one who points me in the right direction
From: http://www.stsci.edu/hst/udf
"The ACS-WFC raw data and the associated calibration files for the Hubble Ultra Deep Field are now available. Users are asked to retrieve them via anonymous ftp from caches at STScI, ST-ECF or the CADC rather than submit requests through the HST archive. Users may also request the raw data on DVDs by sending email to archive@stsci.edu."
WOW - there IS more to everything than what we see!! The 'aliveness' of it all.
WAY more of everything than we can imagine, without this kind of aid. The Hubble was worth it - despite the cogent arguments you proffer, TP1024. It's what we got, and it does pretty cool science.
@21 Radiant Rose:
What an excellent response to seeing this.
I love the Hubble Deep Field camera, but I agree with post 10.
This video didn't do anything for me, and the script, narration and music were mediocre.
very cool.
@10 Anonymous:
That's actually what the music of the spheres sounds like. Our atmosphere blocks out most of it.
#16 - I'm not sure duplicates would be quite as cheap as you suggest, but they'd certainly be cheaper.
Consider that in effect there ARE at least 10 more Hubble-like satellites that (presumably) mostly share a common design:
http://en.wikipedia.org/wiki/KH-11
And apparently they've gotten by without servicing or return, though the Air Force certainly seemed to be keen on that idea back when the Shuttle was still on the drawing board.
Between bringing this, the Atlantic article on a computational universe, and that damned squirrel photo, BoingBoing is truly living up to its slogan today.
Thank you BoingBoing, and all the people who contribute to it.
Around 2:20, the narrator says that these galaxies are traveling away from us faster than the speed of light. Er, what?
I had to think about that one. However...if two objects are traveling at the speed of light in opposite directions, they're separating at double the speed of light. As to the question of how we could see them, I assume that they are accelerating. The light that we're looking at now happened 13 billion years ago when they were moving away at a lesser speed.
I wish it didnt end with the term "the heavens" not the most scientific word. too semi-religious for my taste.
#31, .. from the special relativity page at wikipedia:
"Composition of velocities – velocities (and speeds) do not simply 'add', for example if a rocket is moving at 2⁄3 the speed of light relative to an observer, and the rocket fires a missile at 2⁄3 of the speed of light relative to the rocket, the missile does not exceed the speed of light relative to the observer. (In this example, the observer would see the missile travel with a speed of 12⁄13 the speed of light.)"
Poor Antinous stuck in a Gallileian universe. If two objects are travelling at the speed of light in opposite directions they are separating at the speed of light, according to Einsteinian relativity. Similarly, light shining back at us will be moving at lightspeed no matter the speed of the source. (The color will change drastically, but it's speed remains constant.)
I know it's counterintuitive and frankly batshit crazy, but as hundreds of experiments have proven (Starting with Michelson and Morley even before Einstein), that is the way the universe really works.
It's not that these 'faster-than light' galaxies are moving through space that fast but that the space between galaxies is ever expanding and eventually in trillions of years most galaxies will be moving away from each other at greater than light speeds at which point no new light after that threshold will be visible.
Solitaire is right. If you want to understand how that works, start looking for a thing called "de Sitter horizon".
Even accounting for the speed of expansion of the universe, they still can't go faster than the speed of light.
Or, maybe they can, but our current science says they can't, so the narrator was still wrong.
Object cannot travel through space faster than the speed of light. However, if space is expanding, then the distance between objects can grow arbitrarily fast.
It's not that the distant galaxies are moving away from us through space, it's that the space between us and the galaxies is expanding.
*HEAD THROBBING*
Antinous,
In calculations involving velocities near the speed of light, all that brain-wrenching special relativity stuff comes into play. The usual unbelievable-but-true things happen as you approach lightspeed: time slows down, mass increases, and distances shrink along the direction of travel. Another weird occurrence is that no matter how fast two objects move apart from each other (as measured by a neutral observer in the middle), neither will ever perceive the other as receding faster than c (speed of light). So if the Milky Way and Galaxy Zarkon start off near one another, and Alice stays in between them in her restaurant and watches both galaxies accelerate to near the speed of light in opposite directions, the mind-boggling result is that everyone sees everyone else receding at (almost) the same speed. It's completely counter-intuitive.
The assertion in the video that some galaxies are receding faster than c is a bit sloppy. It makes it sound like we can see them receding at this speed, which we cannot. Such galaxies can exist, so long as there's enough space between us to expand that fast, but we won't be photographing them. It's like driving along a rubber road that's constantly being stretched. If the road is lengthening faster than you're driving, the friends waiting for you at your destination aren't ever going to see you. There may be galaxies visible in the ultra deep field that will eventually recede faster than the speed of light, but it will be a long time coming from our point of view. And when it eventually does happen, there won't be any galaxy to see--it will have red-shifted into invisibility.
*THROBBING receding*
Thankyou Praline, thankyou very much.
@28:
Usually, when I mention that one I expect people to start waving with tin-foil hats.
But yes, those satellites are there and I don't even want to know who got to get the hundreds of millions in bribes and other money to push the construction cost alone to $2.5 billion dollars. (You should assume that everything that has "aero" and "space" in it is a swamp of corruption, along with most of US economy. Or how do you think the US got into the situation it is in these days?)
Btw, I fully appreciate the science done with Hubble. But the overall execution of the project was a perfect disaster. No amount of results can excuse that. Even if Hubble had found extraterrestrial life, there *must* be outrage in the face of such stupendous waste of resources.
We are talking about billions of dollars. A few billion here, a few billion there and pretty soon you are talking about enough money to eradicate malaria, save millions of lives each year and relief people from misery. (Surviving malaria is no fun either.)
Part 1 of 3:
Antinous and Pantograph @ 31 and 32, there are three observers:
1) Me, watching Antinous going East at the speed of light. And also watching Pantograph going West at the speed of light. No problem here.
2) Antinous, because he's travelling at the speed of light, sees me go by slowly, veeeerrrryyy slowly. In fact, from his point of view, I'm not moving at all. And watching Pantograph go by at the speed of light. No problem for Antinous.
3) Pantograph sees Me as stopped, and sees Antinous go by at the speed of light.
All of equations relating to the speed of light didn't work at the turn of the previous century. Einstein's great insight was that the speed of light was non-varying but 'speed' of time could vary. Then all the equations worked.
There's something called the Tau factor, which is the ratio of your time's 'speed' to the time 'speed' of a non-moving observer. The equation is: Tau = (1 - (v^^2/c^^2))^^0.5, that is 'The square root of one minus v squared over c squared. (thanks, crew of the Leonora Christine!)
(Man! Moveable-type really doesn't like equations, eh?)
If you're moving at half the speed of light then:
v sq. / c sq. =
[v squared over c squared]
v sq. = (0.5c) sq. = (0.5 times 0.5 times c times c)
(half of c) squared is the same as (0.5 squared) times (c squared)]
So: (0.5) sq. * c sq.) / c sq. =
(0.25 * c sq.) / c sq
Canceling out the c sq.'s, you get:
0.25/1 which is 1/4. Plugging this back into the Tau equation:
sq.root (1 - 1/4) = sq.root (3/4). The square root of 3/4 is around 0.866. So, when you're traveling at half the speed of light, your time runs at about 86% of the speed of the person watching you go by.
Back to my statement above:
If you're travelling at the speed of light:
Tau = square root of ( 1 - c sq./c sq.) =
square root of (1 - 1) or the square root of zero.
So, problem....
(Gah! I forgot to put a "Part 2 of 2" earlier..)
So, Part 3 of 3:
As you work out the equation for increasingly larger values of v, you see that the Tau factor increases and tends towards infinity. When you reach c (which is impossible, trust me, I've tried), your 'time' relative to an outside observer is infinite or more clearly, you see the outside observer ("Me", in my example), as having time that is 'stopped'.
Thus, when you watch Pantograph zip by, (s)he seems to be traveling at the speed of light. (I can't tell if Pantograph is a he or a she - (s)he zipped by too fast.)
No paradox!
It's full of stars!
One way to think about the expansion of space is "every X years, every linear foot increases by 1 inch." So the distance between you and an object 12 billion light years away is increasing by 1 billion light years per X years, even though neither one of you is "moving."
And yes, things can and do recede at faster than the speed of light. We see light that is 13.7 billion years old, but when it was emitted the objects we're seeing were much closer, and "now" (which is an increasingly tricky concept, the more physicsy you get) they are much farther away than 13.7 billion light years, specifically about 46.5 billion light years. One consequence of this is that our cosmic horizon, the farthest stuff whose light will ever reach us or affect us in any way, is getting closer.
I don't care how fast the universe is expanding, from the point of view of any observer *within* the universe, objects within it cannot move faster than the speed of light.
Any observation that relies on an observer outside the universe is surely pointless (or, religion).
I was going to point-out the innocent error in Antinous' thinking (Two objects going opposite directions etc.) when I saw that he had already been corrected by numerous other posters.
"My hat's off" to the high caliber of BB's readership.
And Antinous, don't feel bad; what you said was thought to be true, until about ~1910 or so, when Einstein proposed the Special Theory of Relativity.
And until radioactivity was discovered, just before 1900, physicists thought that they pretty much knew everything about nature, and there was only some minor explaining still to do.
The sobering thought I have: most people don't know calculus, or (heaven forbid) differential equations. And those areas of mathematics are about 400 years old. So it is true that the "newest" math most people know is 400+ years old!
This being the case, it is almost no wonder people can't wrap their head around other issues, like global warming or healthcare. Their knowledge of science dates from the Middle Ages.
If you took a poll of the public, and our politicans, and asked them if a 1 pound cannonball and a 100 pound cannonball were dropped from a tall building, would they hit the ground at ~ the same time, they would answer "No. The heavier object would impact first."
This kind of stuff always makes me feel so tiny. Now I have to go find a video that shows how many quarks are in one of my cells just to balance things out.
Other fun with peoples grasp of science trivia: most folks outside of the sciences have an Aristotelian-grasp of physics issues like inertia.
I think it was about 10-15% of the test subjects who have, even worse, a Wil-E-Coyote mental model of what happens when someone drives off a cliff.
This is one of the reasons why I think flying cars are a nightmareish scenario :D
"Space is deep." -Hawkwind
#39:
Perfect timing Rob, thanks for the chuckle.
Great, everything I do today is going to seem even more pointless than usual.
That was moving beyond words, thanks for posting it.
I realized when watching this that the entire Star Trek franchise takes place in our own galaxy. Even our imagination has not caught up with exploring the vastness of reality.
Mojave,
Do not read this unless you are prepared to enter the Total Perspective Vortex.
If you were to don a spacesuit, hop into your transporter, and teleport to a random spot in the universe, you could expect to see nothing but the big black void. There is of course a chance you would land within spotting distance of a galaxy, or maybe even inside one, on the surface of a verdant, oxygen rich, pleasure-domed planet... but it's pretty slim. You are far more likely to find yourself floating all alone in a world of total darkness.
It's that bad. I recommend Brainspore's quark therapy.
Refering to @35 and @36 above, where the universe expansion would push objects beyond the de Sitter Horizon ... Wouldn't we then 'see' the galaxies apparently winking out of existance?
Like A. Clarke's _The Nine Billion Names of God_ ...
PaulR @ 43:
Antinous and Pantograph @ 31 and 32, there are three observers:
1) Me, watching Antinous going East at the speed of light. And also watching Pantograph going West at the speed of light. No problem here.
Let's make the observed speeds 0.9 c (90% of the speed of light), since only massless particles like photons can actually travel at lightspeed.
2) Antinous, because he's travelling at the speed of light, sees me go by slowly, veeeerrrryyy slowly. In fact, from his point of view, I'm not moving at all. And watching Pantograph go by at the speed of light. No problem for Antinous.
Um, no. If you see Antinous moving away from you at 0.9 c, then he will see you moving away from him at 0.9 c as well. The two observations are symmetric.
As for Pantograph -- from Antinous's point of view (that is, in Antinous' rest frame), Pantograph is moving away from him at a speed of 0.994 c (99.4% of lightspeed). [*]
3) Pantograph sees Me as stopped, and sees Antinous go by at the speed of light.
Nope. Pantograph sees you as moving away from him at 0.9 c (the same speed you see him moving away from you). And he sees Antinous moving away from him at 0.994 c.
(All this is for motions through space, which isn't really what's going on with distant galaxies and the expanding universe...)
[*] The standard formula for adding velocities in special relativity (e.g., here) is v_total = (v1 + v2) / (1 + (v1*v2/c^2)). If we express velocities in terms of c and plug in the numbers for our situation, then this is v_total = (0.9 + 0.9) / (1 + (0.9*0.9/1^2)) = 0.994, more or less.
And now my mind has been blown.
@42 TP1024:
Waste in science spending is a harm to science, but I'm tired of hearing how it's somehow harmful to mankind. If we spent ten times as much on Hubble, but decided not to bail out the banks, we'd have much, much, much more money to fight disease and poverty with. And yet we at least got something for the money we spent on Hubble.
Spending on space gets way more criticism per dollar than anything else, even military. I don't understand why.
Spending on space gets way more criticism per dollar than anything else, even military. I don't understand why.
I respectfully suggest that the National Endowment for the Arts gets more criticism per dollar, considering that people complain about them wasting taxpayer money on art that they didn't even fund (I'm thinking Christo in particular here).
At its height the NEA was every conservative commentator's favorite whipping boy, probably because of Mapelthorpe's whip 'n boy photos. But the NEA never had more than the tiniest sliver of NASA's budget.
This video was nicely done, but of course could have been done better in a number of ways, like most everything could.
I'm a retired astrophysicist from the STScI. I regret to say that the above comments range from wrong to irrelevant to pseudo-knowdgeable (yes, I mean you, TP1024) to lovely to useful (thanks, udf). As for post #4, that's my little brother. Posters should proof-read, though that is sooo yesterday.
The engineers, some dishonest, bungled Hubble from the beginning; the astronomers fixed it. Yes, it was frightfully expensive, and all that money would have benefitted astronomy better had it been spent elsewhere, like on the ground for people and observatories, but try to get that kind of money for something so unglamorous! Financially it has been good to me, but my astrophysics thesis advisor would have liked to tear the STScI down and sew salt on the earth, as Scipio did to Carthage.
I opposed the idea of the Space Shuttle back in the 70s when it was huckstered to Congress by NASA with a myriad of false promises. Anyone remember the 2-week turn-around time to launch again promised by NASA? Obviously utter nonsense, but who ever called Congressmen scientists? Hardly a 'shuttle' in real life! (Why it's called STS) It is a Rube Goldberg contraption, vastly expensive to maintain, and obviously prone to disaster from the get-go, as has been proved in practice. It's a tribute to the mechanics who rebuild each orbiter after each flight that it works at all.
The narration fails to state that the Orion UDF was obtained on reserved Director's Time, as no such observing proposal would have been approved by the TAC (Telescope Allocation Committe). The Director was noble to allocate all his time (~10%) and more to this one project. The narration errs in stating that the red shifts were 'measured'. They were not, but merely estimated from the colors of the galaxies by assuming that they all had the same intrinsic color, which they do not, as galaxies evolve. The galaxies are too faint to get a spectrum, which is the only way a red shift can be measured.
Repairing the Hubble in space with servicing missions was essential from the beginning to make it work and to keep it working, as there were many failures, starting with sending the wrong mirror into space. A non-servicable telescope this complicated would have been space junk. The original, politically necessary, mistake was to launch a single telescope this complicated instead of several less complicated cheaper telescopes. Creeping features.
Exscept for the UDF, the Hubble is now superseded by the new technology used in the large ground telescopes, for which the Hubble has been reduced to being a scout for interesting objects better now seen from the ground.
There was an initial, stupendously stupid, intent by NASA to bring the telescope back to Earth for servicing, but wiser heads prevailed, as one retrieval would have destroyed it, and two trips would have been needed for each servicing, instead of just one.
Since the telescope is obsolete, it makes no sense to spend the billion or so to bring it back as a museum piece. That billion can go to malaria or bilharzia. After the next crippling failure, it will be destroyed in the atmosphere. The last servicing mission should keep it for a while, though it could not attend to all the problems. The telescope's ground counterpart, the STScI, will live on as a center for research and archive.
Comments above on adding speeds of light refer to special relativity. However, in something like the UDF general relativity must be used, so "the owls are not what they seem". The relationsip of the red shift to distance and age becomes more subtle. The narrator is correct, because we and the observed galaxies are not observed in the same rest frame in flat space.
Spending on space projects actually get *less* criticism than most other spending, despite the fact that the more expensive projects are largely a waste of money, like the ISS. (Even military, TP1024??) NASA now wants to set up a moon base, then go to Mars. Greater follies would be hard to imagine, save playing Global Thermonuclear War, even just with Joshua. However, once a mission is approved, it *must* be adequately funded by clear-eyed people, else it will likely go the way of several "smarter, faster, cheaper" NASA missions, to oblivion in deep space.
@65 Jim Roberts (who is responding to me, not TP1024):
Well, possibly not even military. NASA's budget is under 20 billion dollars per year, the military budget is over 500 billion, and I've personally heard more than 1/25th as many complaints about wasting money on space as the military. But maybe that's selection bias?
At any rate, my point is that complaining about investment in space as taking away from humanitarian projects is disingenuous. It's like complaining about breathing out as the cause of global warming - ignoring the vast majority of the problem and focusing on one tiny part of it. If you want to talk about dramatically inefficient use of funds allocated to science, I'll agree with you.
At the end of the movie, one of the very last galaxies going off the screen to the right looks a lot like the Crab Nebula, which is a supernova remnant. Is this just due to visual artifacts, or did Hubble Ultra Deep Field also manage to photograph the debris of an explosion the size of an entire galaxy?
@ praline and mojave -
Given that we can see the andromeda galaxy with the naked eye even from within our own galaxy, it seems to me that out in the middle of empty space without any stars around to ruin our night vision we would likely see a galaxy or three, right?
JTIII,
On average there is about one galaxy for (roughly) every 10^18 cubic light years of space, which would be a cube a million light years on a side. As you point out, we can see the Andromeda Galaxy, which is 2.4 million light years distant from us, give or take (number may have changed a little since I last checked). So IF galaxies were evenly distributed throughout the universe then yes, we would expect to see a few with the naked eye from any random point. The spoiler is that galaxies are grouped in clusters, and clusters in superclusters. Between the superclusters are unspeakably vast voids, and it is in one of these voids that you're most likely to land. In this case, everything would be out of sight.
@Jim Roberts
The references to special relativity were intended only to correct a misconception amongst some posters about the composition of (near lightspeed) velocities, not to provide a general explication of the UDF! But in any case, when you say 'the narrator is right', do you mean that gravitational effects can make it possible to image distant galaxies even though they are receding faster than the speed of light due to the metric expansion of space? If so, an explanation, or pointer towards one, would be happily received.
It was pleasant not to get boiling oil poured on me for comment #65.
Corrections and expansions:
Committe -> Committee
The TAC at the Space Telescope is always called 'the tack'. The original word for T does not yield easily to cursory research. After posting, I had doubts, so I asked my wife, Head of IT at the STScI, if it stood for Telescope or Time. My recollection was Telescope, and that seems to be the *usual* understanding, including on the stsci.edu site. However, at most observatories and on other orbiting telescopes it almost always stands for Time.
Sorry for mistaking TP1044 (the @42 TP1024 stuck in my mind) for the ubiquitous Anonymous on the military funding remark.
The narration states that some of the galaxies 'are' as far away as 47 billion l.y. (though the Universe is only about 14+ billion years old). This statement is of very questionable meaning, as the assumption behind it is that they would be at that distance when the space from here to there would have the same curvature as the space near us has *now*, but of course 'then' it would be even flatter here, etc.
The cosmological red shift over distances so great as to see changes in the curvature of the Universe with time, as is seen in the UDF, is best understood not as a measure of relative velocity but as a measure of the change in curvature of the Universe between when the light was emitted and detected.
As the curvature of the Universe grows less as it expands over the time the photon travels, the light 'waves' stretch with space. This makes them redder. When the change in curvature is small, the red shift can be understood as a velocity in the ordinary Newtonian or Special Relativistic sense, but not when it is large.
I do not know any better explanation for laypersons without physics or math training, but one can find various accurate explanations and interpretations in the text "Gravitation" by Misner, Thorne, and Wheeler (1973), Box 17.2 (good luck!) and Section 25.4, which is simple but assumes you already know everything. I see that the very same book, which I bought for $20 in 1973, is now $112.38 on Amazon.
Aside on black holes: Because the time in our frame slows to zero (the time axis points inward) as the event horizon forms asymptotically, black holes from our point of view *never actually form*. The Russian term for this effect, "frozen stars", makes this clear, which the unfortunate term "black holes" does not. Thus *in our frame of reference* there are no actual black holes in the Universe, so it is wrong though convenient to speak of them as if there are. However, for phenomena well away from the forming event horizon, such as in an accretion disk or jets, it makes little difference in astrophysics, which is lucky to get numbers to a within factor of five.
Aside on black holes: Because the time in our frame slows to zero (the time axis points inward) as the event horizon forms asymptotically
@Jim Roberts,
Many thanks for the comments clarifying cosmological versus Doppler redshifts. I will check out MTW. There is also an excellent article, by Odenwald and Fienberg, written for the layperson and explaining the implications of general relativity for this discussion.
for #72, Praline
Re the article: As Voltaire once wrote, if I had more time, I'd have written a shorter letter. The article does not explain the cosmological red shift coherently, as I read it.
Furthermore, it needed adult supervision -
dilation -> dilatation
menageri -> menagerie
ruberik -> rubric (wrong word, anyway)
The article does not explain the cosmological red shift coherently, as I read it.
It doesn't? I guess I better call it a day, because I thought it was solid, apart from the typos. One of the co-authors, Odenwald, appears to have a sterling academic pedigree, and works for NASA doing public outreach. He even says he won the NASA 'Excellence in Outreach' award in 1999 from the Goddard Space Flight Center. So if he can't explain it coherently... I'm a goner. But it was fun while it lasted!
@74
I'm not going to reread it, but I failed to see any sentence like, "The wavelenth of light extends in proportion to the expansion of the universe as it travels." But I did read a lot of brush.
Beware of credentials, like 'outreach'. The STScI has these too, and they say the silliest things on the local NPR station WYPR (they don't like it's being called 'wiper'). One went on from the STScI OPO to be director of that center of astronomical research, the Griffith 'Observatory' in Griffith Park in LA. Outreach people are flacks. They get rewarded for flackitude by their masters.
As for GSFC, well, I can tell some stories... My wife tolerates them because she has to. I didn't.
Don't be a goner; buck up! You got the MTW lingo right, and I am favorably disposed toward pralines.
hubba hubba
Wow
and....here we are worrying about my car...my house...my land...WE ARE NOTHING! Once you ponder upon this and really, really think about this, everything around you will disolve..not physically, but mentally!
thanks
DC
Very humbling indeed. So tell me now that we are alone, if we are that would make us so special don't you think. We are proving daily that the human race is far from special, we can't even look after our own 'grain of sand' for heavens sake!
The reason hubble was sent out out of space was because it's hard to observe dim stars and star activities from Earth. The Earth's atmosphere blocks or blurs out lot of information, and often gives wrong information. For example, the atmosphere blurring the star light, will make the star look bigger, therfore giving the wrong radius.
Earth's city lights also interferes with the rays of lights trying to go through the atmosphere, and thats why Hubble is much more useful in taking visual observation and pictures in outer space. There is limitation to what we can observe visually on earth's surface.
It better fit, since the shuttle was built to take Hubble up there in the first place!