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How Can a Star Be Older Than the Universe?

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Re: How Can a Star Be Older Than the Universe?

#101

Post by leggomylibro »

lacker wrote: post #99
leggomylibro wrote: post #98

Earlier quoted context omitted.

So, is it possible for an event in the Milky Way to ever affect GN-z11 (or vice-versa)? Or are the galaxies permanently 'read-only' to each other?

There is no such thing as “read-only” in physics. If we can observe the other galaxy, that means it is affecting the particles in this galaxy. Even if it’s just a single molecule in a telescope responding to a photon that hit it from the other universe.

I guess that makes sense, thanks. I was wondering if it might have been something like the theories of what might happen much later in the universe's life, where things eventually get so far apart while still accelerating that light can't travel between them. But it couldn't be something like that if we can see the other galaxy, right?

Re: How Can a Star Be Older Than the Universe?

#103

Post by thisBrian »

leggomylibro wrote: post #101
lacker wrote: post #99

Earlier quoted context omitted.

There is no such thing as “read-only” in physics. If we can observe the other galaxy, that means it is affecting the particles in this galaxy. Even if it’s just a single molecule in a telescope responding to a photon that hit it from the other universe.

I guess that makes sense, thanks. I was wondering if it might have been something like the theories of what might happen much later in the universe's life, where things eventually get so far apart while still accelerating that light can't travel between them. But it couldn't be something like that if we can see the other galaxy, right?

That still holds true, eventually nearby clusters will go beyond our "observable" view.

Re: How Can a Star Be Older Than the Universe?

#104

Post by ebg13 »

marzell wrote: post #70
ajay-d wrote: post #59

GN-z11 is a galaxy that's 32 billion light years away. Here's the note from wikipedia: At first glance, the distance of 32 billion light-years (9.8 billion parsecs) might seem impossibly far away in a Universe that is only 13.8 billion (short scale) years old, where a light-year is the distance light travels in a year, and where nothing can travel faster than the speed of light. However, because of the expansion of t…

Seriously... what's the difference between 'universe expansion' and 'travel'? A particle can't travel faster than c but it can effectively if the universe expands in addition to its travel speed? Are there any established sci-fi concepts that replace the concepts of wormholes with 'universe compression'?

> what's the difference between 'universe expansion' and 'travel'?

Travel happens inside the universe and expansion doesn't? If a rock is sliding along a stretchy sheet, stretching the sheet will make other things on the sheet move farther away from the rock, potentially faster than the fastest that the rock can slide, even though the rock doesn't move any faster.

Re: How Can a Star Be Older Than the Universe?

#105

Post by sthomas1618 »

hirundo wrote: post #79

I think, by Occam's Razor, the most likely explanation is that there's a skybox surrounding the solar system that Voyager 1 may run into any day now, like Truman Burbank at the end of The Truman Show. It seems to be a more parsimonious explanation of the available facts that we're looking at the result of a super duper planatarium projector, as opposed to an actual vast and frequently inexplicable universe.

Reminds me of https://en.m.wikipedia.org/wiki/Century_Rain

Re: How Can a Star Be Older Than the Universe?

#106

Post by samplatt »

marzell wrote: post #70
ajay-d wrote: post #59

GN-z11 is a galaxy that's 32 billion light years away. Here's the note from wikipedia: At first glance, the distance of 32 billion light-years (9.8 billion parsecs) might seem impossibly far away in a Universe that is only 13.8 billion (short scale) years old, where a light-year is the distance light travels in a year, and where nothing can travel faster than the speed of light. However, because of the expansion of t…

Seriously... what's the difference between 'universe expansion' and 'travel'? A particle can't travel faster than c but it can effectively if the universe expands in addition to its travel speed? Are there any established sci-fi concepts that replace the concepts of wormholes with 'universe compression'?

Just because the universe is expanding at c doesn't mean everything inside it is getting bigger at c. Due to the way mass curves spacetime, mass stays more or less the same size (in comparison to the rest of the empty universe, anyway) - it is mostly only the EMPTY parts of space that get stretched out at c. This means that distances between things are getting bigger all the time... BUT things are still able to travel through space, so they get further away even faster.

Imagine two people (which are galaxies) walking in the same direction on a travelator (which is spacetime). Ordinarily one person would reach the end, and then in a predictable amount of time so would the other. But if the travelator is expanding evenly in both directions, then the distance between the two people will increase, even though they're walking at the same speed.

Re: How Can a Star Be Older Than the Universe?

#108

Post by Dylan16807 »

mannykannot wrote: post #91
swebs wrote: post #87

Earlier quoted context omitted.

It wouldn't work out because it wouldn't match what our telescopes are observing. This image has a good example of what's happening https://upload.wikimedia.org/wikipedia/commons/c/c7/Space_Ex... You can see that from any given point: 1. Every other point is moving away from you 2. Points further away are moving away at a faster rate This could only work out if space were expanding. If it were an explosion instead, e…

That actually demonstrates the opposite: despite the fact that the images themselves show the expansion of a grid in a two-dimensional space, each of the dots appears, from its perspective, to be at the center of the expansion, unless you either specify an absolute frame of reference, or (which amounts to the same thing) can identify the edge of the expanding region. Furthermore, our telescopes have only observed fro…

> That actually demonstrates the opposite: despite the fact that the images themselves show the expansion of a grid in a two-dimensional space, each of the dots appears, from its perspective, to be at the center of the expansion, unless you either specify an absolute frame of reference, or (which amounts to the same thing) can identify the edge of the expanding region.

The image isn't enough to demonstrate the difference. But the speed of light is, along with the way acceleration and redshift work.

> Of course, we can figure out what it would look like, but if that is your argument, then it is circular.

A chain of logic that starts with the evidence we have, goes on to what telescopes show elsewhere, and then concludes about expansion, is not circular.

You might have some specific circular argument in mind, but there are non-circular arguments for what GP is saying.

Re: How Can a Star Be Older Than the Universe?

#110

Post by ssijak »

lottin wrote: post #39

Here we go again... "scientists would look at the ripples in the fabric of space and time". Am I the only one who finds this expression very confusing? What fabric? There is no fabric. Space and time are coordinates. They do not exist physically at all. There cannot be a fabric of space and time.

Well, as farbas I understand quantum loop gravity, there is a fabric of space and time
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