The Lemon Fool

Posted: **July 27th, 2022, 10:19 am**

Bubblesofearth wrote:How can the galaxy be 35bn LY's away if the universe is only 13.8bn years old?

Is this a mistake or am I missing something/

BoE

The universe is expanding faster than the speed of light*. Before you quote Einstein, nothing is moving faster than light, it's space that's expanding. An analogy:

Take a partially inflated balloon and, using a felt tip pen, draw some spots on it. Then inflate it more. The spots themselves don't move, they're still on the same bit of balloon you drew them on, but they've all moved further from each other 'cos the "space" between them has expanded.

Now, as for the confusing measurement of galactic distances, it's all a matter of which measure ... here's another analogy:

Imagine a moving walkway. Jane is standing at the start of the moving walkway (but not on it), and Joe is on it and, of course, moving away from Jane. After a while Joe rolls a ball along the moving walkway towards Jane. At the point he does so he is X feet away from Jane but, as he continues moving away from her, by the time the ball reaches Jane, Joe is Y feet away.

Joe is the galaxy and Y is 35bn light years.

P.S. As well as X & Y there is a third distance, being the distance the ball travelled....

* And actually it's expanding faster the further away things are. Get your head round that!

Posted: **July 27th, 2022, 10:55 am**

mc2fool wrote:The universe is expanding faster than the speed of light*. Before you quote Einstein, nothing is moving faster than light, it's space that's expanding. An analogy:

Take a partially inflated balloon and, using a felt tip pen, draw some spots on it. Then inflate it more. The spots themselves don't move, they're still on the same bit of balloon you drew them on, but they've all moved further from each other 'cos the "space" between them has expanded.

Now, as for the confusing measurement of galactic distances, it's all a matter of which measure ... here's another analogy:

Imagine a moving walkway. Jane is standing at the start of the moving walkway (but not on it), and Joe is on it and, of course, moving away from Jane. After a while Joe rolls a ball along the moving walkway towards Jane. At the point he does so he is X feet away from Jane but, as he continues moving away from her, by the time the ball reaches Jane, Joe is Y feet away.

Joe is the galaxy and Y is 35bn light years.

P.S. As well as X & Y there is a third distance, being the distance the ball travelled....

* And actually it's expanding faster the further away things are. Get your head round that!

Yes, I have heard about the expanding universe theory but surely once you get to a distance that is moving away from us faster than the speed of light then light from objects at, or greater than, that distance would no longer be able to reach us?

To use your analogy it would be the distance Joe is away from Jane such that the ball can no longer reach Jane because the walkway is moving quicker than the ball.

BoE

Posted: **July 27th, 2022, 11:06 am**

Bubblesofearth wrote:Yes, I have heard about the expanding universe theory but surely once you get to a distance that is moving away from us faster than the speed of light then light from objects at, or greater than, that distance would no longer be able to reach us?

To use your analogy it would be the distance Joe is away from Jane such that the ball can no longer reach Jane because the walkway is moving quicker than the ball.

BoE

Yes, that's true, the number of things (other galaxies etc) that we can see is shrinking! That's why scientists talk about the observable universe, which is circa 14bn light years across, while also postulating that the universe is infinite. Of course, objects that were within the observable universe when their light started coming towards us may no longer be so now...

Posted: **July 27th, 2022, 11:16 am**

Bubblesofearth wrote:
To use your analogy it would be the distance Joe is away from Jane such that the ball can no longer reach Jane because the walkway is moving quicker than the ball.

BoE

That’s correct, and what will ultimately happen. I heard Brian Cox explaining it on the radio, and have tried but failed to find the episode for you.

Posted: **July 27th, 2022, 1:46 pm**

GrahamPlatt wrote:
Bubblesofearth wrote:
To use your analogy it would be the distance Joe is away from Jane such that the ball can no longer reach Jane because the walkway is moving quicker than the ball.

BoE

That’s correct, and what will ultimately happen. I heard Brian Cox explaining it on the radio, and have tried but failed to find the episode for you.

https://bigthink.com/starts-with-a-bang/universes-galaxies-unreachable/

94% of the universe’s galaxies are permanently beyond our reach
Even if we traveled at the speed of light, we'd never catch up to these galaxies.
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The universe is expanding, with every galaxy beyond the Local Group speeding away from us. Today, most of the universe's galaxies are already receding faster than the speed of light. All galaxies currently beyond 18 billion light-years are forever unreachable by us, no matter how much time passes.

Posted: **July 27th, 2022, 1:55 pm**

ursaminortaur wrote:https://bigthink.com/starts-with-a-bang/universes-galaxies-unreachable/

94% of the universe’s galaxies are permanently beyond our reach
Even if we traveled at the speed of light, we'd never catch up to these galaxies.

So what is the basis of that "94%" ? 94% of what, the total number of galaxies in the entire universe? How could that figure be known?

Posted: **July 27th, 2022, 3:09 pm**

XFool wrote:
ursaminortaur wrote:https://bigthink.com/starts-with-a-bang/universes-galaxies-unreachable/

94% of the universe’s galaxies are permanently beyond our reach
Even if we traveled at the speed of light, we'd never catch up to these galaxies.

So what is the basis of that "94%" ? 94% of what, the total number of galaxies in the entire universe? How could that figure be known?

The estimated total number of galaxies in the visible/observable universe.* Though since new telescopes such as the James Webb are allowing us to see earlier/ more distant galaxies than ever before and we still don't quite know exactly when the very first galaxy formed that is probably an under estimate since all these newly discovered distant galaxies will also be unreachable.

* The comological principle assumes that the universe is homogeneous and isotropic on the large scale hence counting the number of galaxies seen in a deep field view of a small part can be used to calculate a good estimate of the total number in the visible universe to the depth of that deep field view.

Posted: **July 27th, 2022, 3:10 pm**

ursaminortaur wrote:All galaxies currently beyond 18 billion light-years are forever unreachable by us, no matter how much time passes.

That's comforting, because it means their more advanced inhabitants can never discover that our planet is largely inhabited by nincompoops.

V8

Posted: **July 27th, 2022, 3:36 pm**

ursaminortaur wrote:
XFool wrote:
ursaminortaur wrote:https://bigthink.com/starts-with-a-bang/universes-galaxies-unreachable/

94% of the universe’s galaxies are permanently beyond our reach
Even if we traveled at the speed of light, we'd never catch up to these galaxies.

So what is the basis of that "94%" ? 94% of what, the total number of galaxies in the entire universe? How could that figure be known?

The estimated total number of galaxies in the visible/observable universe.* Though since new telescopes such as the James Webb are allowing us to see earlier/ more distant galaxies than ever before and we still don't quite know exactly when the very first galaxy formed that is probably an under estimate since all these newly discovered distant galaxies will also be unreachable.

So this is 94% of the galaxies in the visible universe, not in the entire universe. And "permanently beyond our reach" means only that we can not, even in principle, physically now reach them, not that they are currently invisible to us?

Posted: **July 27th, 2022, 5:27 pm**

XFool wrote:
ursaminortaur wrote:
XFool wrote:
ursaminortaur wrote:https://bigthink.com/starts-with-a-bang/universes-galaxies-unreachable/

94% of the universe’s galaxies are permanently beyond our reach
Even if we traveled at the speed of light, we'd never catch up to these galaxies.

So what is the basis of that "94%" ? 94% of what, the total number of galaxies in the entire universe? How could that figure be known?

The estimated total number of galaxies in the visible/observable universe.* Though since new telescopes such as the James Webb are allowing us to see earlier/ more distant galaxies than ever before and we still don't quite know exactly when the very first galaxy formed that is probably an under estimate since all these newly discovered distant galaxies will also be unreachable.

So this is 94% of the galaxies in the visible universe, not in the entire universe. And "permanently beyond our reach" means only that we can not, even in principle, physically now reach them, not that they are currently invisible to us?

Yes - the boundary of the observable universe is the largest theoretical distance from which signals could have reached us since the big bang. The universe itself could be much bigger or even infinite (if that makes sense) but signals from any object beyond the boundary of the observable universe could not have reached us in the time which has passed since the big bang and hence we cannot know anything about such objects.

https://en.wikipedia.org/wiki/Observable_universe

The word observable in this sense does not refer to the capability of modern technology to detect light or other information from an object, or whether there is anything to be detected. It refers to the physical limit created by the speed of light itself. No signal can travel faster than light, hence there is a maximum distance (called the particle horizon) beyond which nothing can be detected, as the signals could not have reached us yet. Sometimes astrophysicists distinguish between the visible universe, which includes only signals emitted since recombination (when hydrogen atoms were formed from protons and electrons and photons were emitted)—and the observable universe, which includes signals since the beginning of the cosmological expansion (the Big Bang in traditional physical cosmology, the end of the inflationary epoch in modern cosmology).

And "permanently beyond our reach" means we cannot reach then if we started travelling now or in the future at the speed of light or slower through space. We might one day be able to reach them if we could find a way of in effect travelling faster than light by manipulating space time, eg with warp drive or a wormhole, rather than travelling through space. Recent developments looking at the possibility of creating a warp drive make that more plausible than it was in the past since they have removed the need for negative energy though current concepts still require infeasibly large amounts of normal energy.

https://www.warpnews.org/human-progress/new-theory-can-make-warp-drives-possible-this-is-how/

Many questions remain, but the physicist Erik Lentz has found a solution to the biggest problem, the need for negative energy. In an article that’s garnered much attention, Erik Lentz shows how positive,i.e., ordinary, energy is enough to create a Warp Drive bubble if you take advantage of hyperbolic space-time instead of linear. Thus another geometric solution of Einstein's field equations.
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The amount of energy needed in Lentz's theory, and his "bubble" of 200 meters in diameter, is about one-tenth of the sun's mass. But he believes that it is likely that progress can be made in physics when it comes to this, as the amount of negative energy needed in Alcubierre's theory has been downgraded as the field of research has evolved.

Posted: **August 23rd, 2022, 7:31 am**

Some fantastic new images of Jupiter from the James Webb Telescope -

With giant storms, powerful winds, auroras, and extreme temperature and pressure conditions, Jupiter has a lot going on. Now, NASA’s James Webb Space Telescope has captured new images of the planet. Webb’s Jupiter observations will give scientists even more clues to Jupiter’s inner life.

“We hadn’t really expected it to be this good, to be honest,” said planetary astronomer Imke de Pater, professor emerita of the University of California, Berkeley. De Pater led the observations of Jupiter with Thierry Fouchet, a professor at the Paris Observatory, as part of an international collaboration for Webb’s Early Release Science program. Webb itself is an international mission led by NASA with its partners ESA (European Space Agency) and CSA (Canadian Space Agency). “It’s really remarkable that we can see details on Jupiter together with its rings, tiny satellites, and even galaxies in one image,” she said.

Source article that's got much more details related to these Jupiter images - https://blogs.nasa.gov/webb/2022/08/22/webbs-jupiter-images-showcase-auroras-hazes/

Cheers,

Itsallaguess

Posted: **September 21st, 2022, 5:27 pm**

New pictures of Neptune's rings
https://www.bbc.co.uk/news/science-environment-62984658

James-Webb is a technological marvel

--kiloran

Posted: **October 12th, 2022, 6:24 pm**

James Webb telescope solves dusty star mystery

BBC News

It's one of the most striking images we've yet seen from the new super space telescope James Webb.

"Many people were rather puzzled by it when it first popped up on social media in September, but astronomers in the know were delighted because of the insights they could draw."

Posted: **December 12th, 2022, 9:39 am**

James Webb Space Telescope 'fingerprints' earliest galaxies

BBC News

It's not much to look at - just a little red blob with the rather quirky name of JADES-GS-z13-0.

"But this faint smudge, imaged by the James Webb Space Telescope, is the "most distant galaxy" so far confirmed by gold-standard measurement."

Posted: **December 25th, 2022, 6:03 pm**

James Webb telescope: Amazing images show the Universe as never before

BBC News

James Webb is opening up the infrared Universe

Posted: **January 12th, 2023, 4:00 pm**

James Webb telescope traces arcs of dusty star formation

BBC News

It's another stupendous image from the new super space telescope James Webb.

"The picture shows NGC 346, a region about 200,000 light years from Earth where a lot of stars are being created."

PS. I do wish journalists would drop that meaningless "super telescope" label when describing the James Webb infra-red space telescope.

Posted: **January 12th, 2023, 4:05 pm**

XFool wrote:"The picture shows NGC 346, a region about 200,000 light years from Earth where a lot of stars are being created."

One light year is 5.88 trillion miles
My head hurts thinking about that distance and just small and insignificant we are

Posted: **January 12th, 2023, 4:17 pm**

pje16 wrote:
XFool wrote:"The picture shows NGC 346, a region about 200,000 light years from Earth where a lot of stars are being created."

One light year is 5.88 trillion miles
My head hurts thinking about that distance and just small and insignificant we are

Small, yes, but insignificant? The human brain is the most incredible creation we know about, a consequence of billions of years of evolution. If intelligent life is limited to planet Earth then you could argue it is the most significant thing in the universe. If it isn't then that's even more amazing. Every step we take to a greater understanding of the cosmos takes us closer to answering that question. I only hope I'm still around if/when we do. Sadly (for me) chances are I won't be.

BoE

Posted: **January 12th, 2023, 4:31 pm**

Bubblesofearth wrote:
pje16 wrote:
XFool wrote:"The picture shows NGC 346, a region about 200,000 light years from Earth where a lot of stars are being created."

One light year is 5.88 trillion miles
My head hurts thinking about that distance and just small and insignificant we are

Small, yes, but insignificant? The human brain is the most incredible creation we know about, a consequence of billions of years of evolution.

BoE

Incredible creation perhaps, yet it hurts just trying to comprehend an enormously large distance :lol:

doolally

Posted: **January 13th, 2023, 11:46 am**

pje16 wrote:
XFool wrote:"The picture shows NGC 346, a region about 200,000 light years from Earth where a lot of stars are being created."

One light year is 5.88 trillion miles
My head hurts thinking about that distance and just small and insignificant we are

Well, the closest star to us is Proxima Centauri, only 4.3 light years away. You have to put it in context. When we're young, one mile is a long way.

On a bike, much closer. By car, 10 miles is close. By plane....etc. One day, we may have devices capable of bending space/time for a split second, but enough to get us across vast distances.

and just small and insignificant we are

Miss a few mortgage or credit card payments! You soon discover how important you are! 8-)

Steve

The Lemon Fool

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