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James Webb Telescope

acbytesla said:
We can all come up with far more wasteful uses of money than JWST. I also wouldn't describe JWST a waste.

It's not the cost in dollars per se that concerns me. It's the opportunity cost. It's having our best minds exploring the universe when they should be saving the planet. But obviously the same thing could be said about developing weapon systems, making video games.
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How JWST is useful
1. It inspires people to take up science as a career.
2. People learn about science and then want to learn more about other science.
3. Undermines religion and other stupid ideas.
4. The photos.
5. Learning how to build such things as JWST.

Edit. One of the uses of Appolo 8 was that they took a photo of Earthrise. This inspired people to start caring for the environment. So maybe the environment (or something just as valuable) will be helped thanks to the JWST.
 
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rjh01 said:
How JWST is useful
1. It inspires people to take up science as a career.
2. People learn about science and then want to learn more about other science.
3. Undermines religion and other stupid ideas.
4. The photos.
5. Learning how to build such things as JWST.

Edit. One of the uses of Appolo 8 was that they took a photo of Earthrise. This inspired people to start caring for the environment. So maybe the environment (or something just as valuable) will be helped thanks to the JWST.
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I'm sure that's probably true. And maybe in the long run it will benefit society far more than what I would like to see happen.
 
Star Talk podcast today:



The blurb:
James Webb Space Telescope’s first full-color images have arrived! On this explainer, Neil deGrasse Tyson and comic co-host Chuck Nice explore the deepest views of the cosmos yet with NASA astrophysicist, Knicole Colon.

Discover nebulas, gas clouds, galaxies, and stars in the new images captured by JWST. We enjoy space in all its beauty, but also ask: what do these images helps us uncover? Find out about the objectives of JWST as represented by the new images and about the countless scientists and engineers who made it all happen. Learn about the atmospheres of exoplanets, Stephan’s Quintet, and the Carina Nebula. What are we hoping to discover as scientists capture even more data and images? Who do we find biomarkers on planets many lightyears away? Finally, will JWST bring us one step closer to discovering life?
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I have a pondering the universe question.

With all those galaxies 13-14 [fill in however many billions of years] distant, where are they today? Are they in the same place only more developed? But then there has been expansion.
 
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Skeptic Ginger said:
I have a pondering the universe question.

With all those galaxies 13-14 [fill in however many billions of years] distant, where are they today? Are they in the same place only more developed? But then there has been expansion.
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What counts as the “same place” when space itself is changing?

The closest you can get to that on a cosmological scale is “comoving”: being stationary relative to the average flow of matter around you. Galaxies are generally not stationary relative to the comoving reference frame, but their velocities are low (in relativistic terms) relative to this frame. They will not only evolve, but also cluster, collide, etc.
 
rjh01 said:
3. Undermines religion and other stupid ideas.
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I don’t think it does that (if your conception of religion ends with creationists, you need to get out more) but more importantly, you really, really don’t want the public to think it does. That’s a good way to get funding for NASA to evaporate.
 
Skeptic Ginger said:
I have a pondering the universe question.

With all those galaxies 13-14 [fill in however many billions of years] distant, where are they today? Are they in the same place only more developed? But then there has been expansion.
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Ziggurat said:
What counts as the “same place” when space itself is changing?

The closest you can get to that on a cosmological scale is “comoving”: being stationary relative to the average flow of matter around you. Galaxies are generally not stationary relative to the comoving reference frame, but their velocities are low (in relativistic terms) relative to this frame. They will not only evolve, but also cluster, collide, etc.
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I think what SG is asking is, how far away are these extremely redshifted galaxies today, and I think the current record-holder in that regard is a galxy called GN-z11, which has a redshift over 11, and is about 32 billion ly distant by now, presumably. This is because the space in between has been expanding. It doesn't move that fast in its own frame of reference of course.
 
Ziggurat said:
What counts as the “same place” when space itself is changing?

The closest you can get to that on a cosmological scale is “comoving”: being stationary relative to the average flow of matter around you. Galaxies are generally not stationary relative to the comoving reference frame, but their velocities are low (in relativistic terms) relative to this frame. They will not only evolve, but also cluster, collide, etc.
Click to expand...

So if they are in an expanding space I can see why they aren't getting closer to us but why isn't there a blur of light from their moving to the left or to the right as space expands?

It's hard to imagine space is and has been expanding uniformly since the Big Bang.

I'm going to have to ponder some more.
 
Puppycow said:
I think what SG is asking is, how far away are these extremely redshifted galaxies today, and I think the current record-holder in that regard is a galxy called GN-z11, which has a redshift over 11, and is about 32 billion ly distant by now, presumably. This is because the space in between has been expanding. It doesn't move that fast in its own frame of reference of course.
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I am asking where are they today.

But if they are closer then why can't we see light from the closer galaxy? Expanding space makes sense for distance, but what about as space expands laterally? Again, OK, we are in the same space that is expanding laterally.

But wouldn't space have to be expanding uniformly and wouldn't it have to have always expanded uniformly laterally?

I'm sure if I ponder more it will all make sense to me.
 
Ziggurat said:
I don’t think it does that (if your conception of religion ends with creationists, you need to get out more) but more importantly, you really, really don’t want the public to think it does. That’s a good way to get funding for NASA to evaporate.
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Science has seriously undermined religion and other nutty ideas. It used to be that everyone was a creationist, but then Wallice and Darwin came along. If you got sick you used to go to someone who got their medical knowledge from the ancient Greeks until they discovered that a lot of what was in the books was wrong. And the planets went around the Earth in perfect circles. And everything outside of the Earth was perfect. Authorities were not to be questioned. After all, a doctor would know the best treatment for you was better than you. All changed.
 
Skeptic Ginger said:
I am asking where are they today.

But if they are closer then why can't we see light from the closer galaxy? Expanding space makes sense for distance, but what about as space expands laterally? Again, OK, we are in the same space that is expanding laterally.

But wouldn't space have to be expanding uniformly and wouldn't it have to have always expanded uniformly laterally?

I'm sure if I ponder more it will all make sense to me.
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Space expands in all directions, but the shortest distance between any two objects is still a straight line (albeit sometimes the space is curved due to gravity). Does that make sense? We aren't going to see much lateral movement, and it wouldn't show up as a redshift in any case.

Think of a loaf of bread expanding with raisins in it. As loaf gets bigger, the distance between all of the raisins in the dough gets bigger.
 
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Skeptic Ginger said:
So if they are in an expanding space I can see why they aren't getting closer to us but why isn't there a blur of light from their moving to the left or to the right as space expands?

It's hard to imagine space is and has been expanding uniformly since the Big Bang.

I'm going to have to ponder some more.
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Expansion means the distances between things is increasing. Nothing will expand in any direction except directly away from you.

The comoving distance is the same, because, that's its purpose. Have a way to talk about distances regardless of whether t=0 (now) or sometime in the past or present.

The proper distance however is always increasing with time.

The galaxies that we see today have moved farther away from us since that light was emitted. When talking about galaxies we can find their z redshift, and then figure how long it took for their light to reach us, from which we can figure out where the galaxy is now (generally speaking).

As far as I can tell.
 
Skeptic Ginger said:
So if they are in an expanding space I can see why they aren't getting closer to us but why isn't there a blur of light from their moving to the left or to the right as space expands?
Click to expand...

Why would there be? Are you imagining some sort of motion blur? They don’t move fast enough for that.

It's hard to imagine space is and has been expanding uniformly since the Big Bang.
Click to expand...

Expansion is pretty isotropic. But if you mean changing rates over time, that wouldn’t cause blurring.
 
Ziggurat said:
Why would there be? Are you imagining some sort of motion blur? They don’t move fast enough for that.
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That reminds me of an analogy. A racecar and an airplane.

An airplane flying at 35.000 feet is going about 500 mph. A racecar on the ground only 200 mph. But if you are in a racecar going 200 mph you will feel like you are moving much faster than you feel when you are in a plane looking down at the ground. It's because of the angles.
 
Ziggurat said:
Why would there be? Are you imagining some sort of motion blur? They don’t move fast enough for that....
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But there would have been billions of light years for them to move and create that motion blur.

But never mind, I'm getting a clearer picture of the issue now.
 
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