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Author Topic: Webb Space Telescope  (Read 9669 times)

Offline Elwyn Aud

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Webb Space Telescope
« on: December 25, 2021, 09:25:06 AM »
I see they successfully got it launched and on its way. Seems like it was one of the most glitch free launches I've seen recently. No last minute delays or hiccups. Hope it lives up to all the hype. It will take it a month to reach its destination orbit of 1 million miles. Should be free from orbiting space debris at that distance. (Yes, I know that's not the reason for the chosen  orbiting spot.)

Offline Tim Wescott

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Re: Webb Space Telescope
« Reply #1 on: December 25, 2021, 12:42:37 PM »
Now we will all see the truth.

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Offline qaz049

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Re: Webb Space Telescope
« Reply #2 on: December 25, 2021, 03:27:03 PM »
Now we will all see the truth.

Motorman 8)

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Offline Mike Griffin

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Re: Webb Space Telescope
« Reply #3 on: December 25, 2021, 04:33:40 PM »
Now we will all see the truth.

Motorman 8)


Offline john e. holliday

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Re: Webb Space Telescope
« Reply #4 on: December 25, 2021, 08:48:55 PM »
I still can't believe there are people believing the Earth is flat after all the pictures taken from space of the Big Blue Marble called Earth. D>K
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Offline Gary Dowler

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Re: Webb Space Telescope
« Reply #5 on: December 25, 2021, 10:43:57 PM »
I still can't believe there are people believing the Earth is flat after all the pictures taken from space of the Big Blue Marble called Earth. D>K
Yes indeed. It does trouble the mind trying to grasp how grown, educated, people can believe such nonsense.  That, and their companion idea that gravity isn’t real, things just have weight……. LL~ LL~ LL~

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Offline Ken Culbertson

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Re: Webb Space Telescope
« Reply #6 on: December 25, 2021, 11:55:35 PM »
I still can't believe there are people believing the Earth is flat after all the pictures taken from space of the Big Blue Marble called Earth. D>K
I have it on good authority that those pictures were in fact of a big blue marble. D>K

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Offline kevin king

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Re: Webb Space Telescope
« Reply #7 on: December 26, 2021, 01:08:05 AM »
If the earth really was flat the millennials would be falling off the edge taking selfies by now.

Offline Dave Hull

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Re: Webb Space Telescope
« Reply #8 on: December 26, 2021, 02:13:24 AM »
A truly awesome piece of equipment. The final assembly was done just down the street from me in the NG High Bay, formerly TRW. Having worked on deployment mechanisms, pin-pullers and insulation blankets in the past, what these guys are attempting is amazing in terms of the sequential complexity. A long string of successes must occur just for all the mechanisms to deploy. They showed a pin release module during the NASA live feed. Something like 107(?) of the things all have to work exactly right when activated. And, each one is separately cross-strapped (redundant).  I was most excited to see the initial deployment of the solar panel from the trans-stage camera as the two continued separation. That is a very rare sight...

Way too cool....

Dave

PS--If you guys haven't heard of the "Birds Aren't Real" phenomenon, you might want to check it out so you can see behind some of the stuff you hear.  Some of the young folks have run around the last few years (especially on the internet) telling anyone and everyone that birds aren't real. They are drones. Drones the government is using for surveillance. And other things.

The reality is this is their way of protesting a lot of nonsense crap that people repeat over and over as if it is true. So if someone started telling them about the flat earth, they would happily agree and then start telling the person that birds aren't real.

The logic can be extended to other topics if you wish....

Offline Mark wood

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Re: Webb Space Telescope
« Reply #9 on: December 26, 2021, 02:17:56 PM »
I had a young man in my A&P class who was convinced the we have never landed a man on the moon. I didn't probe just exactly how far his denial of reality is but asked him why he felt such was true and I pointed out that I had watched the landing live. His reply was we had massive conspiracies back then. True but the ability to pull off something like fake the landing would be much more difficult than actually doing it. Especially fooling tens of thousands of people working in the program. He didn't believe in the space shuttle either, to which I asked him if he'd ever been to Florida and seen the boosters or a launch. Or been to Edwards to see a landing. Of course he hadn't. He didn't have much to say when I explained to him that my father had been one of the people who worked out the 6 DOF calculations necessary for docking in space and that I personally had seen the Saturn V booster, a shuttle launch and a shuttle land.
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Offline Brett Buck

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Re: Webb Space Telescope
« Reply #10 on: December 26, 2021, 02:26:34 PM »
I had a young man in my A&P class who was convinced the we have never landed a man on the moon. I didn't probe just exactly how far his denial of reality is but asked him why he felt such was true and I pointed out that I had watched the landing live. His reply was we had massive conspiracies back then. True but the ability to pull off something like fake the landing would be much more difficult than actually doing it. Especially fooling tens of thousands of people working in the program. He didn't believe in the space shuttle either, to which I asked him if he'd ever been to Florida and seen the boosters or a launch. Or been to Edwards to see a landing. Of course he hadn't. He didn't have much to say when I explained to him that my father had been one of the people who worked out the 6 DOF calculations necessary for docking in space and that I personally had seen the Saturn V booster, a shuttle launch and a shuttle land.

  It's really kind of pointless to argue with these guys, they are the prototypes for the Dunning-Kruger effect, reality means something entirely different for them than the rest of us.

    Brett

Offline Mark wood

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Re: Webb Space Telescope
« Reply #11 on: December 26, 2021, 02:45:47 PM »
  It's really kind of pointless to argue with these guys, they are the prototypes for the Dunning-Kruger effect, reality means something entirely different for them than the rest of us.

    Brett

I had  to look that up. I think it is clear this individual was definitely in that zone. Although, I have to say with so much VR capability today it is easy to see how such skepticism could be formed. Kids less than 30 have grown up with technology that could be harnessed to purpurate such a feet. But not in the time when we did it. They don't understand that. To them, using a slide rule is unimaginable let alone flying to the moon without super computers on board.

Resulting random thought, I used to have a small slide rule in my flying box for calculating speed. 

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Offline Tim Wescott

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Re: Webb Space Telescope
« Reply #12 on: December 26, 2021, 03:24:58 PM »
... and that I personally had seen the Saturn V booster, a shuttle launch and a shuttle land.

Well, clearly you're part of the conspiracy!
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Offline Tim Wescott

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Re: Webb Space Telescope
« Reply #13 on: December 26, 2021, 03:26:40 PM »
Looks like the first test images are in!
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Offline Avaiojet

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Re: Webb Space Telescope
« Reply #14 on: December 26, 2021, 03:45:05 PM »
They're going to place this thing 100 million miles out and it will orbit the sun. It will not be in earth orbit.

Gee, doesn't the earth orbit the sun? So, if need be, how will they make repairs?

9 billion dollars and they cannot service it. By design? Gee, they thought of everything.

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Offline Brett Buck

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Re: Webb Space Telescope
« Reply #15 on: December 26, 2021, 05:14:59 PM »
Mention Dunning-Kruger and up he pops...


They're going to place this thing 100 million miles out and it will orbit the sun. It will not be in earth orbit.

Gee, doesn't the earth orbit the sun? So, if need be, how will they make repairs?

9 billion dollars and they cannot service it. By design? Gee, they thought of everything.

    So, given your extraordinary experience in aerospace engineering, and generalized genius-level intellect, what are your thoughts on the albedo thermal input?   Those irredeemable dummies at Northrop-Grumman and NASA await your inputs with bated breath!

  Brett
« Last Edit: December 26, 2021, 10:14:48 PM by Brett Buck »

Offline Brett Buck

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Re: Webb Space Telescope
« Reply #16 on: December 26, 2021, 05:31:52 PM »
I had  to look that up. I think it is clear this individual was definitely in that zone. Although, I have to say with so much VR capability today it is easy to see how such skepticism could be formed. Kids less than 30 have grown up with technology that could be harnessed to purpurate such a feet. But not in the time when we did it. They don't understand that. To them, using a slide rule is unimaginable let alone flying to the moon without super computers on board.

    Having a very powerful computer would undoubtedly make it harder and more expensive - because if you have that capacity, someone will feel compelled to use it. Meaning, you run afoul of the most dreaded words in the aerospace industry - software development (with the associated programming guilds/cults).

Quote
Resulting random thought, I used to have a small slide rule in my flying box for calculating speed.

    I use a slide rule about 3 times a day at work. That, or a calculator -  even though I have professional versions of MATLAB with every conceivable toolbox on 4 separate computers, and FORTRAN and C/C++ compilers.

     Brett

Offline Tim Wescott

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Re: Webb Space Telescope
« Reply #17 on: December 26, 2021, 07:25:15 PM »
    I use a slide rule about 3 times a day at work. That, or a calculator -  even though I have professional versions of MATLAB with every conceivable toolbox on 4 separate computers, and FORTRAN and C/C++ compilers.

     Brett

My son and wife (both software engineers) were recently expressing disbelief at me that FORTRAN is still a current language (we were talking about scientific computing packages, and how they all sit on top of the same LINPACK, EIGENPACK and BLAS code).  If it weren't for the mention of a slide rule, I'd show them this quote.
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Offline Mark wood

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Re: Webb Space Telescope
« Reply #18 on: December 26, 2021, 07:34:23 PM »
Well, clearly you're part of the conspiracy!

Don't tell anyone please.
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Offline Brett Buck

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Re: Webb Space Telescope
« Reply #19 on: December 26, 2021, 08:16:09 PM »
My son and wife (both software engineers) were recently expressing disbelief at me that FORTRAN is still a current language (we were talking about scientific computing packages, and how they all sit on top of the same LINPACK, EIGENPACK and BLAS code).  If it weren't for the mention of a slide rule, I'd show them this quote.

  FORTRAN is still the primary language of engineering, at least as far as most of our systems are concerned. Garbage languages like Java, Perl, Python MATLAB, and even the accursed Excel and other script-kiddie languages are sometimes used for analysis tools (that don't directly contribute to the mission). There has been some use of C++, which brings with it the stench of object-oriented programming, which is OK for some applications but not a great choice for life-critical systems.

    Brett

Offline wwwarbird

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Re: Webb Space Telescope
« Reply #20 on: December 26, 2021, 10:10:25 PM »
Yes indeed. It does trouble the mind trying to grasp how grown, educated, people can believe such nonsense.  That, and their companion idea that gravity isn’t real, things just have weight……. LL~ LL~ LL~

Gary

 Yeah, and the same people are allowed to participate in our elections.
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Offline Fredvon4

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Re: Webb Space Telescope
« Reply #21 on: December 27, 2021, 04:14:53 AM »
"Yeah, and the same people are allowed to participate in our elections"

yes , early, often, mail in, and in person, sans any ID check in many places
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Offline John Hammonds

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Re: Webb Space Telescope
« Reply #22 on: December 27, 2021, 06:35:33 AM »
They're going to place this thing 100 million miles out and it will orbit the sun. It will not be in earth orbit.

Just to correct you Charles it's 1 million miles not 100 million miles. (So only just over 4 times the distance to the moon).

TTFN
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Offline Brett Buck

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Re: Webb Space Telescope
« Reply #23 on: December 27, 2021, 11:16:23 AM »
Just to correct you Charles it's 1 million miles not 100 million miles. (So only just over 4 times the distance to the moon).

   And I am sure Charles will explain to us all the physics behind the LaGrange points, and the relevance of them to this mission, so as to point out how NASA got it all wrong.

        Brett

Offline Mike Griffin

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Re: Webb Space Telescope
« Reply #24 on: December 27, 2021, 12:02:20 PM »
Just to correct you Charles it's 1 million miles not 100 million miles. (So only just over 4 times the distance to the moon).

TTFN
John.

Thank you John, you beat me to it.  100 million miles would put it just a little less than halfway to Mars.


Mike

Offline Ken Culbertson

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Re: Webb Space Telescope
« Reply #25 on: December 27, 2021, 12:17:19 PM »
Looks like the first test images are in!
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Offline Mike Scholtes

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Re: Webb Space Telescope
« Reply #26 on: December 27, 2021, 12:40:00 PM »
So, conspiracy-theory jokes aside, can one of our qualified engineer types explain to us who are in awe of the technology but don't have degrees in astrophysics what this new telescope will do for science? I get that it is a big deal but lack the ability to understand just how big.

Offline Brett Buck

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Re: Webb Space Telescope
« Reply #27 on: December 27, 2021, 12:58:12 PM »
So, conspiracy-theory jokes aside, can one of our qualified engineer types explain to us who are in awe of the technology but don't have degrees in astrophysics what this new telescope will do for science? I get that it is a big deal but lack the ability to understand just how big.

   It's not *that* big a deal for science, but does advance the cause. This telescope works in infrared, unlike Hubble that operates in (largely) visible light. Hubble is necessarily limited in scope because of the "red shift" phenomenon - the further away something is, the older it is and the the faster it is going away from us, meaning that the light is subject to Doppler shifts to lower frequencies - towards the "red". At some point, things are so far away that Hubble can't see it because the light is shifted too far. Looking at IR expands this scope, it can see further back in time.

    The other phenomenon that matters is that the Earth's atmosphere absorbs and reflects a large fraction of IR light, so you can't put this type of telescope on the ground without it becoming disproportionately large, and in any case it absorbs different frequencies of IR to different degrees.

    So, effectively, this telescope will allow us to view much older objects with uncorrupted spectra, with a reasonably-sized telescope.

     BTW there are very good (and fairly obvious) reasons that you want to move this telescope out of low Earth orbit, and additional reasons to put it at a legrange point, but I want to send Charles into a panic trying to figure it out before he changes the subject. The best engineering reason is, apparently, not directly stated on the internet, but obvious nonetheless. Needless to say, the people at NASA who specified the spacecraft, and the people at Northrup-Grumman (formerly TRW) who designed and built it (along with the 3-400 spacecraft they have built to date) know *exactly what they are doing*, succeed or fail.

     Brett

Offline Tim Wescott

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Re: Webb Space Telescope
« Reply #28 on: December 27, 2021, 01:13:39 PM »
So, effectively, this telescope will allow us to view much older objects with uncorrupted spectra, with a reasonably-sized telescope.

It turns out it's also ideal for looking at new stars being formed, along with their new planets.  It's expected to be able to sense the atmospheric composition of earth-sized planets, and to tell if the twice-earth sized planets out there are giant earth-like planets, or miniature Neptune-like planets.

Needless to say, the people at NASA who specified the spacecraft, and the people at Northrup-Grumman (formerly TRW) who designed and built it (along with the 3-400 spacecraft they have built to date) know *exactly what they are doing*, succeed or fail.

Oh, you would say that.
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Offline Mike Scholtes

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Re: Webb Space Telescope
« Reply #29 on: December 27, 2021, 01:47:55 PM »
Thanks all, that gives me at least a basic understanding of how it differs from Hubble and Earth-based telescopes.

To bring me back down to Earth again, today I got a Christmas card from an old modelling buddy featuring two Super Ringmasters! That kind of technology, I can understand!

Offline Brett Buck

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Re: Webb Space Telescope
« Reply #30 on: December 27, 2021, 01:51:09 PM »
Oh, you would say that.

   I note that I work for neither one, I just have professional respect for their capabilities.

      Brett


Offline Mark wood

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Re: Webb Space Telescope
« Reply #31 on: December 27, 2021, 02:05:24 PM »
   I note that I work for neither one, I just have professional respect for their capabilities.

      Brett

The lab where I worked at ASU was in the same Physics department basement as the guys who helped design and build the Humble Telescope. They had some awesome stuff to play with.
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Re: Webb Space Telescope
« Reply #32 on: December 27, 2021, 02:25:40 PM »
   .............the physics behind the LaGrange points, and the relevance of them to this mission, so as to point out how NASA got it all wrong.

        Brett

Awww crap!!!!
At first I thought you were talking about music not this other junk!!!

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Re: Webb Space Telescope
« Reply #33 on: December 27, 2021, 02:26:29 PM »
They gott'a lott'a nice girls ha.

You rat!!
You beat me tuit by a few secs....

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Re: Webb Space Telescope
« Reply #34 on: December 27, 2021, 02:44:43 PM »
   It's not *that* big a deal for science, but does advance the cause. This telescope works in infrared, unlike Hubble that operates in (largely) visible light. Hubble is necessarily limited in scope because of the "red shift" phenomenon - the further away something is, the older it is and the the faster it is going away from us, meaning that the light is subject to Doppler shifts to lower frequencies - towards the "red". At some point, things are so far away that Hubble can't see it because the light is shifted too far. Looking at IR expands this scope, it can see further back in time.

     Brett

   This part about looking back in time is what interests me, and wondering what we will see. I'm having trouble comprehending this concept. Everything else will be gravy! Time to most of us is relative to a clock or calendar. Once it's operational, how will what it sees relate to us , here and now? I'm not really sure how to ask the question!!??
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Offline Tim Wescott

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Re: Webb Space Telescope
« Reply #35 on: December 27, 2021, 03:12:46 PM »
   This part about looking back in time is what interests me, and wondering what we will see. I'm having trouble comprehending this concept. Everything else will be gravy! Time to most of us is relative to a clock or calendar. Once it's operational, how will what it sees relate to us , here and now? I'm not really sure how to ask the question!!??
   HAPPY NEW YEAR!
   Dan McEntee

At least on cosmological scales, older = further away, because the universe expands.  Seeing the first stars will confirm some tentative theories, and contradict others.  Then we'll learn more.

Philosophically, it's worth it just to know more.

Practically, no one can foresee a use -- but that's what Hertz said about radio waves when he proved their existence.  I think that trying to predict the power output of stars was also considered to be a pointless endeavor back in the 1920's, except that the problems we had with it led to a far better and more complete understanding of quantum mechanics -- and without quantum mechanics we wouldn't have a lot of the cool technologies we have now, from electronics to medicines to metallurgy to goodness-knows-what.
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Offline Scott Richlen

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Re: Webb Space Telescope
« Reply #36 on: December 27, 2021, 03:33:25 PM »
Quote
  FORTRAN is still the primary language of engineering 

Holy cow!  We were using that back when I got my first job out of college!  Those were the days when they'd bring your tray of cards back with ones sticking up side-ways: those were the ones that got chewed by the card reader or got spit out with some error code.  Or sometimes they'd drop the tray and you then had the joy of putting them all back in order.

Offline Scott Richlen

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Re: Webb Space Telescope
« Reply #37 on: December 27, 2021, 03:40:16 PM »
Quote
  This part about looking back in time is what interests me, and wondering what we will see. I'm having trouble comprehending this concept. 

Dan: think of it this way: everything you see arrives to your eye-ball at the speed of light.  That means that everything you see is "history" - it has already happened and took the time of distance divided by the speed of light to arrive at your eye-ball.  In the typical conditions of our life-experience the speed of light is essentially instantaneous so we don't notice the difference.

Offline Ken Culbertson

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Re: Webb Space Telescope
« Reply #38 on: December 27, 2021, 03:45:26 PM »
Holy cow!  We were using that back when I got my first job out of college!  Those were the days when they'd bring your tray of cards back with ones sticking up side-ways: those were the ones that got chewed by the card reader or got spit out with some error code.  Or sometimes they'd drop the tray and you then had the joy of putting them all back in order.
That dates us a bit.  COBOL used the cards too.  Did some Fortran for Grayhound back in the 80's but I learned pretty quickly that those languages were not suited for business software.  Got into BASIC, not the kiddy versions Microsoft uses but the real ones.  Still using them today and the systems I wrote in the 80's still run on the latest Windows and Unix platforms.

Ken
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Offline Brett Buck

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Re: Webb Space Telescope
« Reply #39 on: December 27, 2021, 09:53:06 PM »
   This part about looking back in time is what interests me, and wondering what we will see. I'm having trouble comprehending this concept. Everything else will be gravy! Time to most of us is relative to a clock or calendar. Once it's operational, how will what it sees relate to us , here and now? I'm not really sure how to ask the question!!??

   I will preface this by saying, to really understand this mathematically, you have to understand General Relativity pretty well, because the "expansion" we are talking about is space-time.

    I presume that everyone understands the general concept of the speed of light, and that the further away something is, the longer the light took to get to you, so, further away  = older. So, for example, when we get data from a Mars lander, that data was taken anything from 3 minutes to 22 minutes in the past when we receive it, depending on the distance. If it's very near us, not far, so not long, on the far side of the sun from us, it is a lot further away, so it takes much longer.

    Same thing with this, the further away it is, the longer it takes the light to get here, so in effect we are looking at something from a long time ago.

     The red-shift effect is where the analogy comes in. It's really a 4-dimensional problem, but the analogy is 3-dimensional. Suppose you have a spherical balloon, and are blowing it up slowly. Take a sharpie, and mark a dot on the surface - that's where we are. An inch away, mark another dot - a nearby object. Then mark a dot exactly the other side of the sphere from us - a distant object. As the balloon expands, the nearby object moves away from you, but pretty slow. The dot on the far side moves much faster away from you.

   Blowing up the balloon, making it bigger and bigger, is analogous to the universe expanding. Of course, the universe does not fall on the surface of a big 3-dimensional sphere or bubble, it's a 4-dimensional sphere or bubble (but not uniform...).

     A 4-d version of that is what the universe is doing - nearby objects move slowly away from you, and far-away objects move faster. The faster they go, the more the doppler shift they get, so, distant/fast moving objects have a lot of doppler shift, visible light toward the red, and then further, to the infrared, and ultimately towards radio wave. So something that looks like, say, a normal star from nearby, might only be seen as a radio source from a long distance.

    This red-shift means that some of the visible light from the star (or galaxy, or supernova, or whatever) is shifted lower, beyond visible light, into the infrared. So to see it, you need a telescope that sees infrared. That's what this telescope does, it sees lower frequencies than visible light, therefore things with a lot of doppler shift, which means it is a long way away, which means the light travel time from that star is from *long ago*, effectively, looking at stars from the early universe.

    The math of some of this is messy, but the idea is relatively simple.

    Brett

   

Offline Brett Buck

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Re: Webb Space Telescope
« Reply #40 on: December 27, 2021, 10:12:27 PM »
Holy cow!  We were using that back when I got my first job out of college!  Those were the days when they'd bring your tray of cards back with ones sticking up side-ways: those were the ones that got chewed by the card reader or got spit out with some error code.  Or sometimes they'd drop the tray and you then had the joy of putting them all back in order.

  Been there, done that. Card stacks on a CDC 3800 computer were still being used in the Air Force Satellite Control Network as recently as 1995 for orbit determination, because they couldn't get it to work with sufficient accuracy on the more modern systems (although still ancient) they had at the time.

   FORTRAN is still actively being developed, in fact, some of the stuff I do couldn't have been done in FORTRAN 77 (standard or with the DEC extensions), which some real steps forward ("ACCESS" = "STREAM", which only showed up in FORTRAN 95 for reading in raw binary data from C/C++ with no record headers or variable-length records), and embedded vector math like:

Code: [Select]
       REAL PHI_E(3), PHI_E_DOT(3), PHI_CTL(3), TAU(3) ! declare control parameters
....


       PHI_CTL = PHI_E + TAU*PHI_E_DOT

instead of writing it out like:

       
Code: [Select]
       DO I=1,3   ! loop through for each axis
            PHI_CTL(I) = PHI_E(I) + TAU(I)*PHI_E_DOT(I)
       ENDDO

   Because it can take advantage of embedded vector math processors. Tim and Howard probably recognize the purpose of such a code snippet, it is the first building block of a satellite or other control system, and completely generic.

   It also has garbage object-oriented features, and indefinite line length which I have banned from our simulations due to lack of readability, and to prevent anyone from using code libraries without understanding what is in them.

     Brett



       
« Last Edit: December 28, 2021, 11:02:20 PM by Brett Buck »

Offline Mark wood

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Re: Webb Space Telescope
« Reply #41 on: December 27, 2021, 10:51:19 PM »
   I will preface this by saying, to really understand this mathematically, you have to understand General Relativity pretty well, because the "expansion" we are talking about is space-time.

    I presume that everyone understands the general concept of the speed of light, and that the further away something is, the longer the light took to get to you, so, further away  = older. So, for example, when we get data from a Mars lander, that data was taken anything from 3 minutes to 22 minutes in the past when we receive it, depending on the distance. If it's very near us, not far, so not long, on the far side of the sun from us, it is a lot further away, so it takes much longer.

    Same thing with this, the further away it is, the longer it takes the light to get here, so in effect we are looking at something from a long time ago.

     The red-shift effect is where the analogy comes in. It's really a 4-dimensional problem, but the analogy is 3-dimensional. Suppose you have a spherical balloon, and are blowing it up slowly. Take a sharpie, and mark a dot on the surface - that's where we are. An inch away, mark another dot - a nearby object. Then mark a dot exactly the other side of the sphere from us - a distant object. As the balloon expands, the nearby object moves away from you, but pretty slow. The dot on the far side moves much faster away from you.

   Blowing up the balloon, making it bigger and bigger, is analogous to the universe expanding. Of course, the universe does not fall on the surface of a big 3-dimensional sphere or bubble, it's a 4-dimensional sphere or bubble (but not uniform...).

     A 4-d version of that is what the universe is doing - nearby objects move slowly away from you, and far-away objects move faster. The faster they go, the more the doppler shift they get, so, distant/fast moving objects have a lot of doppler shift, visible light toward the red, and then further, to the infrared, and ultimately towards radio wave. So something that looks like, say, a normal star from nearby, might only be seen as a radio source from a long distance.

    This red-shift means that some of the visible light from the star (or galaxy, or supernova, or whatever) is shifted lower, beyond visible light, into the infrared. So to see it, you need a telescope that sees infrared. That's what this telescope does, it sees lower frequencies than visible light, therefore things with a lot of doppler shift, which means it is a long way away, which means the light travel time from that star is from *long ago*, effectively, looking at stars from the early universe.

    The math of some of this is messy, but the idea is relatively simple.

    Brett

 

Good job Brett. Cept it's Special Relativity which is the function of space time ie the Lorentz contraction. The one that goes E=Gamma x Mass x (speed of light)^2 , where gamma = 1/(1-V^2/C^2), which reduces to E=MC^2 when V << C and V^2/C^2 approaches 0.  This is also the principle of speed of light is a constant and it is the length as measured by the observe which changes as function of their respective inertial reference  frame L' = Gamma L. When applied to the wavelength of a photon the the redshift becomes  l' = Gamma l. General Relativity is the fabric of space where gravity is function of the local curvature of space.  The one that bends light as it passes high gravitational fields.  What you are describing is the relativistic doppler shifting of light. Anyway, you did good.

The interesting part of this is that there is a finite observable universe and this mission will explore the physics which is occurring along this threshold. There is a dependence upon exactly how cosmic inflation works. The theory is that the space time itself is growing. Within this there are some dependencies on how homogenous the universe truly is, whether it is finite or infinite.

From our point of view, we would be in region of expansion where everything around us growing. With this, as we look farther and farther away objects are moving faster away from us. There is a limit to this, the speed of light. When the expansion is such that the objects are moving relatively at the speed of light away, they can no longer be observed. Anything past that threshold can never be observed from our perspective.

;)
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Offline Brett Buck

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Re: Webb Space Telescope
« Reply #42 on: December 27, 2021, 10:55:04 PM »
Good job Brett. Cept it's Special Relativity which is the function of space time ie the Lorentz contraction. The one that goes E=Gamma x Mass x (speed of light)^2 , where gamma = 1/(1-V^2/C^2), which reduces to E=MC^2 when V << C and V^2/C^2 approaches 0. 

   That is indeed the primary premise of Special Relativity, however, that is not sufficient to explain the relativistic concept of space-time, which requires General Relativity to describe.

     Brett

Offline Mark wood

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Re: Webb Space Telescope
« Reply #43 on: December 28, 2021, 12:28:47 AM »
   That is indeed the primary premise of Special Relativity, however, that is not sufficient to explain the relativistic concept of space-time, which requires General Relativity to describe.

     Brett

Oh this would be an interesting in person discussion. However, contare monfrare. The relativistic nature of space time is in fact special relativity. Special Relativity can be thought of as the portions surrounding the Lorentz contraction. It is the relationship of the inertial observer with respect to how length and time change as a function of the their relative speed with each other. Doppler shifting of light is due to the speed of light being a constant in all rest frames is a fundamental tenant of special relativity. That one rest frame is moving away from another as you describe causes that doppler shift to be measured locally. Another way of thinkin about is my ruler appears to be a different than yours by a function of the rate at which we are moving relative to each other. The stars moving on a expanding sphere as you describe would similarly be doppler shifted. Therefore QED your example is in fact Special relativity.

In general relativity, gravity is derived as a function of the curvature of space-time. Within this the property of a gravitational field is such that an inertial observer in a closed box could not determine if the force from the floor is from being stationary on a massive object or is in fact in an accelerating reference frame. Within special relativity is the feature of gravitational lenses, the bending of light around massive objects which can be verified when observing solar eclipses. The relationship between gravity and space-time is two way interchangeable.

I'll concede that the expansion of the universe, cosmic inflation, does have roots within general relativity. This has more to do with the rate of expansion and whether it fluctuates or not dependent upon the total energy content. However your discussion is the result of this and consequently how the property of light behaves. It's subtle but significant. In one, General Relativity the equations are field equations. In the other, Special Relativity the equations are motion equations. Ultimately General Relativity encompasses special Relativity so in that regard, I would concede, however that's the long way around and much more difficult derivation.
« Last Edit: December 28, 2021, 10:32:03 AM by Mark wood »
Life is good AMA 1488
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Offline Avaiojet

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Re: Webb Space Telescope
« Reply #44 on: December 28, 2021, 09:44:25 AM »
"Space Time."  LL~

Someone should design a model airplane called "Scientific Theory."

Built correctly, it would carry absolutely no weight.

A few years ago a bunch of scientists, there's always a bunch, they hang out in bunches, anyway, they were so excited finding a planet so similar to earth which "they" concluded could support life.

Maybe this new "Webb Space Telescope" can take a close up photo of it.

It's only light years away in another galaxy.

Charles
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Re: Webb Space Telescope
« Reply #45 on: December 28, 2021, 10:23:04 AM »
"Space Time."  LL~
Someone should design a model airplane called "Scientific Theory."
Built correctly, it would carry absolutely no weight.
A few years ago a bunch of scientists, there's always a bunch, they hang out in bunches, anyway, they were so excited finding a planet so similar to earth which "they" concluded could support life.
Maybe this new "Webb Space Telescope" can take a close up photo of it.
It's only light years away in another galaxy.

Charles

Such profundity.  I am in awe.

Keith

Offline Brett Buck

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Re: Webb Space Telescope
« Reply #46 on: December 28, 2021, 11:26:27 AM »
"Space Time."  LL~

Someone should design a model airplane called "Scientific Theory."

Built correctly, it would carry absolutely no weight.

A few years ago a bunch of scientists, there's always a bunch, they hang out in bunches, anyway, they were so excited finding a planet so similar to earth which "they" concluded could support life.

Maybe this new "Webb Space Telescope" can take a close up photo of it.

It's only light years away in another galaxy.

Charles


    Thanks for demonstrating the exactly the grasp of the situation that we all expected.

     Brett

   
« Last Edit: April 15, 2022, 07:27:05 PM by Brett Buck »

Offline Brett Buck

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Re: Webb Space Telescope
« Reply #47 on: December 28, 2021, 11:37:27 AM »

I'll concede that the expansion of the universe, cosmic inflation, does have roots within general relativity. This has more to do with the rate of expansion and whether it fluctuates or not dependent upon the total energy content. However your discussion is the result of this and consequently how the property of light behaves. It's subtle but significant. In one, General Relativity the equations are field equations. In the other, Special Relativity the equations are motion equations. Ultimately General Relativity encompasses special Relativity so in that regard, I would concede, however that's the long way around and much more difficult derivation.

     My point was that to really explain how space-time expands in 4D, you have to use general relativity. I was conceding that people understood the Doppler effect, whether or not they understood Special Relativity and relativistic Doppler effect.

       Brett

Offline Mike Griffin

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Re: Webb Space Telescope
« Reply #48 on: December 28, 2021, 01:47:07 PM »
My mind just cannot grasp infinity.  I defer to God.

Mike

Offline Brett Buck

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Re: Webb Space Telescope
« Reply #49 on: December 28, 2021, 01:55:12 PM »
My mind just cannot grasp infinity.


   No one else does, either. All of our knowledge is just getting us to the point of knowing what questions to ask, we are far from any answers.

     Brett


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