Astronomical question from today's news:

[Moonbeam]

Hubble sees most distant star ever, 28 billion light-years away | CNN

The Hubble Space Telescope has glimpsed the most distant single star it's ever observed, glimmering 28 billion light-years away. The star, nicknamed Eardenel, could be between 50 to 500 times more massive than our sun, and millions of times brighter.

www.cnn.com

How can a star be 28 billion light years away if it's light took 12.9 billion years to reach us?

 

[[DHT]Osiris]

Hubble sees most distant star ever, 28 billion light-years away | CNN

The Hubble Space Telescope has glimpsed the most distant single star it's ever observed, glimmering 28 billion light-years away. The star, nicknamed Eardenel, could be between 50 to 500 times more massive than our sun, and millions of times brighter.

www.cnn.com

How can a star be 28 billion light years away if it's light took 12.9 billion years to reach us?

The key phrase:

“When the light that we see from Earendel was emitted, the Universe was less than a billion years old; only 6% of its current age. At that time it was 4 billion lightyears away from the proto-Milky Way, but during the almost 13 billion years it took the light to reach us, the Universe has expanded so that it is now a staggering 28 billion lightyears away.”

Things can be further away than the universe can be old because the fabric of the universe itself expands.

 

[Pens1566]

Hubble sees most distant star ever, 28 billion light-years away | CNN

The Hubble Space Telescope has glimpsed the most distant single star it's ever observed, glimmering 28 billion light-years away. The star, nicknamed Eardenel, could be between 50 to 500 times more massive than our sun, and millions of times brighter.

www.cnn.com

How can a star be 28 billion light years away if it's light took 12.9 billion years to reach us?

Expansion/movement of the source and destination. It's in the article ...

 

[BoomerD]

Science...it's like magic...except it's real.

 

[sdifox]

Hubble sees most distant star ever, 28 billion light-years away | CNN

The Hubble Space Telescope has glimpsed the most distant single star it's ever observed, glimmering 28 billion light-years away. The star, nicknamed Eardenel, could be between 50 to 500 times more massive than our sun, and millions of times brighter.

www.cnn.com

How can a star be 28 billion light years away if it's light took 12.9 billion years to reach us?

It is prescient and has been running away from Milky Way to get away from your eventual existence here on Earth.

 

[HomerJS]

How long to reach it at warp 9?

 

[Pens1566]

How long to reach it at warp 9?

Depends, do we slingshot around the earth backwards?

 

[Moonbeam]

Expansion/movement of the source and destination. It's in the article ...

Thank you. I got so puzzled by the numbers I didn't see that. I wonder from that now if it means the size of the universe can is known. Given that the universe is not terribly older so I hear than 13.813±0.038 billion years, does that limit how far things can now be apart. Can any star be say 100 billion light years away?

 

[Dave_5k]

Hubble sees most distant star ever, 28 billion light-years away | CNN

The Hubble Space Telescope has glimpsed the most distant single star it's ever observed, glimmering 28 billion light-years away. The star, nicknamed Eardenel, could be between 50 to 500 times more massive than our sun, and millions of times brighter.

www.cnn.com

How can a star be 28 billion light years away if it's light took 12.9 billion years to reach us?

It's running away at warp speed? But on a bit deeper reflection, it actually is a very interesting question.

The Universe is in fact expanding faster than the speed of light. I don't pretend to understand general relativity, but apparently general relativity allows for the possibility of this to happen.

If Eardenel started 4 billion light years away, Earth has moved some 9 billion light years further away = 13 billion years for light to get to Earth including universe expansion. Meanwhile, Eardenel by math must have moved some 15 billion light years in roughly the opposite direction. Which would to the amateur like me, appear to break light speed in a universal sense (15 billion light years in 13 billion years...), but in fact somehow doesn't require upsetting special relativity (locally). Apparently.

 

[Moonbeam]

It is prescient and has been running away from Milky Way to get away from your eventual existence here on Earth.

Everything you fear has already happened. I am not the droid you are looking for.

 

[IronWing]

If the universal can/is expanding faster than the speed of light, what is defining the edge of the universe? Is it the location of the farthest out photons that are now being stretched away from their buddies at a speed faster than they themselves are traveling?

 

[Dave_5k]

If the universal can/is expanding faster than the speed of light, what is defining the edge of the universe? Is it the location of the farthest out photons that are now being stretched away from their buddies at a speed faster than they themselves are traveling?

"The restriction that "nothing can move faster than light" only applies to the motion of objects through space. The rate at which space itself expands — this speed-per-unit-distance — has no physical bounds on its upper limit."

Ask Ethan: How Does The Fabric Of Spacetime Expand Faster Than The Speed Of Light?

Nothing in the Universe can travel faster than the speed of light. So how does space itself do it?

www.forbes.com

Edit: And yes, location between those photons can be stretched apart by space expansion faster than they are themselves (locally) travelling

 

[IronWing]

Follow up: Photons have an energy tied to their wavelength. With the universe is expanding, the measured wavelength changes (red shift). Does the energy carried by each photon also change? Will the microwave background slowly shift down the spectrum to ever longer wavelengths as the universe expands?

 

[MtnMan]

You know how the pitch of the train horn changes as the train approaches then passes your location?

Yea, that...

 

[Moonbeam]

It's running away at warp speed? But on a bit deeper reflection, it actually is a very interesting question.

The Universe is in fact expanding faster than the speed of light. I don't pretend to understand general relativity, but apparently general relativity allows for the possibility of this to happen.

If Eardenel started 4 billion light years away, Earth has moved some 9 billion light years further away = 13 billion years for light to get to Earth including universe expansion. Meanwhile, Eardenel by math must have moved some 15 billion light years in roughly the opposite direction. Which would to the amateur like me, appear to break light speed in a universal sense (15 billion light years in 13 billion years...), but in fact somehow doesn't require upsetting special relativity (locally). Apparently.

I remember thinking, when I read that the universe in not only expanding but that the rate of expansion is accelerating, how puzzling that is if the speed of light is fixed. I always wondered if that means that everything is rushing away to a place where it re appears as the big bang.

 

[[DHT]Osiris]

If the universal can/is expanding faster than the speed of light, what is defining the edge of the universe? Is it the location of the farthest out photons that are now being stretched away from their buddies at a speed faster than they themselves are traveling?

There's a reason we say 'observable universe'. There's technically no known edge of the actual universe.

 

[IronWing]

"The restriction that "nothing can move faster than light" only applies to the motion of objects through space. The rate at which space itself expands — this speed-per-unit-distance — has no physical bounds on its upper limit."

I better grasp the idea of the interior of the universe expanding than what the edge looks like. If the edge is racing away from the outer most photons then how is the edge defined?

 

[IronWing]

There's a reason we say 'observable universe'. There's technically no known edge of the actual universe.

We better send a probe then, armed.

 

[Moonbeam]

Follow up: Photons have an energy tied to their wavelength. With the universe is expanding, the measured wavelength changes (red shift). Does the energy carried by each photon also change? Will the microwave background slowly shift down the spectrum to ever longer wavelengths as the universe expands?

There's a reason we say 'observable universe'. There's technically no known edge of the actual universe.

Yes but if the universe expands from a single point at the speed of light 13+ billion years ago, then why can't one calculate how far two photons can travel from each other in that amount of time whether you can observe it or not?

 

[[DHT]Osiris]

Yes but if the universe expands from a single point at the speed of light 13+ billion years ago, then why can't one calculate how far two photons can travel from each other in that amount of time whether you can observe it or not?

Here's the hat trick, the big bang didn't start at a single point. Started everywhere at once. There's no 'center of the universe' in the same way there's no 'point of rest' in the universe. Everything is relative to everything else. We can only see things a certain distance away and predict how far away it is now.

 

[Paratus]

The key phrase:


Things can be further away than the universe can be old because the fabric of the universe itself expands.

How long to reach it at warp 9?

TOS Warp 9 or TNG Warp 9?

Technically accelerating at 1G continuously you could reach the edge of the observable universe in one human lifetime thanks to time dilation. Of course billions of years would pass back on Earth.

Thank you. I got so puzzled by the numbers I didn't see that. I wonder from that now if it means the size of the universe can is known. Given that the universe is not terribly older so I hear than 13.813±0.038 billion years, does that limit how far things can now be apart. Can any star be say 100 billion light years away?

They can but we wouldn’t be able to see or reach them.

It's running away at warp speed? But on a bit deeper reflection, it actually is a very interesting question.

The Universe is in fact expanding faster than the speed of light. I don't pretend to understand general relativity, but apparently general relativity allows for the possibility of this to happen.

If Eardenel started 4 billion light years away, Earth has moved some 9 billion light years further away = 13 billion years for light to get to Earth including universe expansion. Meanwhile, Eardenel by math must have moved some 15 billion light years in roughly the opposite direction. Which would to the amateur like me, appear to break light speed in a universal sense (15 billion light years in 13 billion years...), but in fact somehow doesn't require upsetting special relativity (locally). Apparently.

The fact that this seems to be to be the case does leave a slight crack open for FTL travel that doesn’t violate relativity. The Alcubierre metric gives hints at that potential.

If the universal can/is expanding faster than the speed of light, what is defining the edge of the universe? Is it the location of the farthest out photons that are now being stretched away from their buddies at a speed faster than they themselves are traveling?

It’s a good question. One model of the universe would consider what falls into our future light cone (basically what could be seen or influenced by light from here) as our own bubble universe with other bubble universes. out there but unreachable by us.

"The restriction that "nothing can move faster than light" only applies to the motion of objects through space. The rate at which space itself expands — this speed-per-unit-distance — has no physical bounds on its upper limit."

Ask Ethan: How Does The Fabric Of Spacetime Expand Faster Than The Speed Of Light?

Nothing in the Universe can travel faster than the speed of light. So how does space itself do it?

www.forbes.com

Edit: And yes, location between those photons can be stretched apart by space expansion faster than they are themselves (locally) travelling

Follow up: Photons have an energy tied to their wavelength. With the universe is expanding, the measured wavelength changes (red shift). Does the energy carried by each photon also change? Will the microwave background slowly shift down the spectrum to ever longer wavelengths as the universe expands?

Yes. As they are stretched they become more “red”. Their wave length becomes longer and longer until they are effectively gone.

The microwave background radiation was originally gamma ray radiation 300K years after the Big Bang. The expansion of the universe has stretched the wavelength all the way down to the microwave range. Further expansion will continue to increase the wavelength.

 

[Dave_5k]

I better grasp the idea of the interior of the universe expanding than what the edge looks like. If the edge is racing away from the outer most photons then how is the edge defined?

I think common belief is that there is no actual edge to the universe (but this is not really known), but there is an edge to what is "observable" universe.

Is space infinite? We asked 5 experts

Despite innovations in telescope and satellite technology, what's beyond our line of sight in space is uncertain. Analysis for The Conversation featuring Anna Moore, Australian National University, Kevin Orrman-Rossiter, University of Melbourne, Sam Baron, Australian Catholic University, Tanya...

www.swinburne.edu.au

 

[Paratus]

Here's the hat trick, the big bang didn't start at a single point. Started everywhere at once. There's no 'center of the universe' in the same way there's no 'point of rest' in the universe. Everything is relative to everything else. We can only see things a certain distance away and predict how far away it is now.

Yup. A good mental model would be to picture a 2D person living on the surface of a sphere. The “center” is at the center of the sphere which is not accessible to the person living on the 2D spherical surface.

 

[[DHT]Osiris]

I think common belief is that there is no actual edge to the universe (but this is not really known), but there is an edge to what is "observable" universe.

Is space infinite? We asked 5 experts

Despite innovations in telescope and satellite technology, what's beyond our line of sight in space is uncertain. Analysis for The Conversation featuring Anna Moore, Australian National University, Kevin Orrman-Rossiter, University of Melbourne, Sam Baron, Australian Catholic University, Tanya...

www.swinburne.edu.au

For a real treat, read Max Tegmark's 'Our Mathematical Universe', math supports the idea of a neverending 'rolling big bang' that each part of the universe/multiverse experiences, and this is just ours.

 

[eelw]

Wonder if this will get bumped up on JWST observing schedule?