13 Billion Year Old Planet of the Milky Way

[ErnieM]

This Nasa article describes the oldest planet in our galaxy estimated to be 13 billions years old.
http://www.nasa.gov/home/hqnews/2003/ju ... lanet.html
This article on Nature shows the oldest galaxy so far detected by Hubble is 13.2 billion years old.
http://www.nature.com/news/2011/110126/ ... 11.47.html

Does this not make the Milky way (or part of it) as old if not older than the oldest galaxy detected by Hubble?

[Chris Peterson]

This Nasa article describes the oldest planet in our galaxy estimated to be 13 billions years old.
http://www.nasa.gov/home/hqnews/2003/ju ... lanet.html
This article on Nature shows the oldest galaxy so far detected by Hubble is 13.2 billion years old.
http://www.nature.com/news/2011/110126/ ... 11.47.html

Does this not make the Milky way (or part of it) as old if not older than the oldest galaxy detected by Hubble?

The Milky Way, like most galaxies, began forming just a few hundred million years after the Big Bang, so it is unsurprising that we observe stars that are 12-13 billion years old. That some such stars have planets is interesting, but not particularly surprising. It is certainly possible that the Milky Way is older than the galaxy discussed in the Nature article. The difference is that we see the Milky Way as it is "now", while we are seeing the distant galaxy as it was early in its formation. The two could be the same age, but we see them at different times.

Another thing to keep in mind is that the galaxy in the article already contains stars, which are obviously even older than the galaxy as a whole as we observe it. That is, we are observing it as it was 13.2 billion years ago, but at that point it already had existed for some period- we aren't seeing the galaxy being born.

[ErnieM]

Chris wrote:

we aren't seeing the galaxy being born

How would anyone know that he or she is witnessing a galaxy being born, 13 billion years ago or last year? How would the image look like? Is the James Web telescope equipped with instruments to detect such events?

[Chris Peterson]

Chris wrote:

we aren't seeing the galaxy being born

How would anyone know that he or she is witnessing a galaxy being born, 13 billion years ago or last year? How would the image look like? Is the James Web telescope equipped with instruments to detect such events?

Nobody understands the details of how galaxies are formed. But the simple fact that we are seeing this body, already containing hundreds of millions or billions of stars, demonstrates that it has been present for some significant length of time before being observed.

[ErnieM]

Chris wrote:

ErnieM wrote:

Chris wrote:

we aren't seeing the galaxy being born

How would anyone know that he or she is witnessing a galaxy being born, 13 billion years ago or last year? How would the image look like? Is the James Web telescope equipped with instruments to detect such events?

Nobody understands the details of how galaxies are formed. But the simple fact that we are seeing this body, already containing hundreds of millions or billions of stars, demonstrates that it has been present for some significant length of time before being observed.

Thank you. Here is what I found the goals set for JWST: https://en.wikipedia.org/wiki/James_Web ... _Telescope

Understanding goals
JWST is the formal successor to the Hubble Space Telescope (HST), but since its primary emphasis is on infrared observation, it is equally fair to consider it a successor to the Spitzer Space Telescope. In fact, JWST will far surpass both those telescopes, being able to see many more and much older stars and galaxies.[22] Observing in the infrared is a key technique for achieving this, because it better penetrates obscuring dust and gas, allows observation of dim cooler objects, and because of cosmological redshift.

Obscuring dust and gas: Infrared astronomy can penetrate dusty regions of space, such as molecular clouds where stars are born, the circumstellar disks that give rise to planets, and the cores of active galaxies which are often cloaked in gas and dust.[23]

Cool objects: Furthermore, relatively cool objects (in this context meaning temperatures less than several thousand degrees) emit their radiation primarily in the infrared, as described by Planck's Law. As a result, most objects that are cooler than stars are better studied in the infrared. This includes the clouds of the interstellar medium, the "failed stars" called brown dwarfs, planets both in our own and other solar systems, and comets and Kuiper belt objects.

The distant universe: Looking beyond our own galaxy to more distant galaxy clusters, quasars, and gamma-ray bursts, the most distant objects viewable are also the "youngest," that is, they were formed during a time period closer in time to that of the Big Bang.[22] We see them today because their light has taken billions of years to reach us. Because the universe is expanding, as the light travels it becomes red-shifted and these objects are therefore easier to see if viewed in the infrared.[23] JWST's infrared capabilities are expected to let it see all the way to the very first galaxies forming just a few hundred million years after the big bang.[24]

WOW!
I can't wait to see the 3-D map of these first galaxies super imposed on the 3-D map of the current universe to get a visualization of the overall expansion of space over time.

[Beyond]

WOW!
I can't wait to see the 3-D map of these first galaxies super imposed on the 3-D map of the current universe to get a visualization of the overall expansion of space over time.

Hmm... The ultimate definition of the term, "Spaced Out"

[Chris Peterson]

I can't wait to see the 3-D map of these first galaxies super imposed on the 3-D map of the current universe to get a visualization of the overall expansion of space over time.

I don't think that concept has any physical meaning. We can already see most of the way to the Big Bang- the IR observations will just extend things another couple hundred million years (in certain wavelengths- we see farther in radio already). You don't see old-new superimposed maps with current data, because we only see objects once. It's not like we can see a galaxy as it was then, and as it is now.

[ErnieM]

Chris wrote:

because we only see objects once.

No argument about this. The images of these very young galaxies are what they looked like and their location at the time as close as possible to the moment of the big bang. Where would we find these young galaxies? Would they be bunch up closer together concentrated in a small sector of the very early universe? What if they are scattered all over and we find them in all directions in the northern, southern, eastern and western hemispheres? What would this mean? Either way, these images, whatever they may be, has the potential of showing what the very early and young universe looked like. Astronomers have a good idea how the "present" universe looks like. Is it not possible to "extrapolate and guess" what the "future" universe can be from these two maps?

[Chris Peterson]

Chris wrote:

because we only see objects once.

No argument about this. The images of these very young galaxies are what they looked like and their location at the time as close as possible to the moment of the big bang. Where would we find these young galaxies? Would they be bunch up closer together concentrated in a small sector of the very early universe? What if they are scattered all over and we find them in all directions in the northern, southern, eastern and western hemispheres? What would this mean? Either way, these images, whatever they may be, has the potential of showing what the very early and young universe looked like. Astronomers have a good idea how the "present" universe looks like. Is it not possible to "extrapolate and guess" what the "future" universe can be from these two maps?

No, it will tell us nothing about what the future universe will be like. We will see just what we see now: no matter how near or how far, the distribution of galaxies is uniform. We don't see them bunched up, and we wouldn't expect to. Seeing back a little farther isn't going to change our understanding of the structure of the early universe, only our understanding of how individual galaxies form.

[ErnieM]

No, it will tell us nothing about what the future universe will be like. We will see just what we see now: no matter how near or how far, the distribution of galaxies is uniform. We don't see them bunched up, and we wouldn't expect to. Seeing back a little farther isn't going to change our understanding of the structure of the early universe, only our understanding of how individual galaxies form.

Supposing JWST finds one galaxy each in the north, south, east and west hemisphere satisfying your uniform distribution statement. These makes the distance between the galaxy pairs in opposite directions "double" the 13 billion light years and the shape of the "then" universe from our present perspective round like a ball. I admit this is an over simplification but still the location of these "oldest" galaxies relative to the our position may give us an image much different than that of the radio microwave background image.
I also expect JWST to find more of the I Zicky 18 galaxy types and reveal their true nature.

[Chris Peterson]

Supposing JWST finds one galaxy each in the north, south, east and west hemisphere satisfying your uniform distribution statement. These makes the distance between the galaxy pairs in opposite directions "double" the 13 billion light years and the shape of the "then" universe from our present perspective round like a ball.

It's not going to find this. We already see farther than JWST will be able to see- the 3 K background (microwave) is from earlier than the earliest galaxies began forming. And it doesn't show symmetrical features, so there is already very strong evidence that the Universe is larger than the observable universe.

What JWST will do is let us see galaxies a few hundred million years younger than the youngest we currently see, which will hopefully answer some basic questions about galaxy formation that are still open (what role did dark matter play, did they start with black holes, or did the black holes come afterwards, etc). We already know that galaxies are uniformly distributed (I'm not considering more local structures, like clusters and filaments), and that isn't going to change with the JWST data. We know where galaxies formed, we just just don't know how, since current telescopes can't quite see far enough to show us one in the process of formation.

[pleas]

Does anyone have any idea where Earth is, relative to the center of the universe?

[neufer]

Does anyone have any idea where Earth is, relative to the center of the universe?

[geckzilla]

Snarky, neufer. Contrary to what we've been told about the earth not being the center of the Universe, it is actually at the center of the observable Universe. As for the rest... who could say.

[pleas]

Both responses much appreciated. It being nearly impossible, as a matter of probability, that we are actually at or near the center of the universe, would being at the center of the observable universe be sufficient to show that we just are not seeing the whole thing and do not know where it ends? Can we get Hawking's input on this?

[neufer]

[b][url=http://www.griffithobservatory.org/vcafe.html][size=150]The Café at the End of the Universe[/size][/url][/b]

---

Both responses much appreciated. It being nearly impossible, as a matter of probability, that we are actually at or near the center of the universe, would being at the center of the observable universe be sufficient to show that we just are not seeing the whole thing and do not know where it ends? Can we get Hawking's input on this?

You can check out one of Hawking's books at the library.

There is really no debate about this.

The center of the universe does NOT exist
(at least not in this universe).

[pleas]

Appreciated. You seem a little defensive about this. Is it a naive question?

[neufer]

Appreciated. You seem a little defensive about this. Is it a naive question?

It is an age old question.

However, the answer is quite trivial for those of us who can easily visualize 5 dimensions.

[Chris Peterson]

Both responses much appreciated. It being nearly impossible, as a matter of probability, that we are actually at or near the center of the universe, would being at the center of the observable universe be sufficient to show that we just are not seeing the whole thing and do not know where it ends? Can we get Hawking's input on this?

The Universe is not a three-dimensional structure, but a four-dimensional one. It has a precise center, which coincides with t=0 (the 4D point where the Big Bang originated). In three dimensions, any point can be considered the center, and it is conventional to treat the position of the observer as such. We are definitely at the center of the observable Universe (which is a 3D sphere around us), and all the theory I know of places us at the center of the entire Universe, when we consider only the three spatial dimensions (with time being the additional dimension that makes up spacetime, and is not a dimension we can independently move along... which is why we can't actually get to the true center of the Universe, since it would require a time machine).

[neufer]

The Universe is not a three-dimensional structure, but a four-dimensional one.
It has a precise center, which coincides with t=0 (the 4D point where the Big Bang originated).

This is a cute and rather unique way of thinking, Chris.

But wouldn't you have to include all the space time points that are separated from
the Big Bang by zero space time distance [i.e., s = 0 where ]

[Ann]

Both responses much appreciated. It being nearly impossible, as a matter of probability, that we are actually at or near the center of the universe, would being at the center of the observable universe be sufficient to show that we just are not seeing the whole thing and do not know where it ends? Can we get Hawking's input on this?

The Universe is not a three-dimensional structure, but a four-dimensional one. It has a precise center, which coincides with t=0 (the 4D point where the Big Bang originated). In three dimensions, any point can be considered the center, and it is conventional to treat the position of the observer as such. We are definitely at the center of the observable Universe (which is a 3D sphere around us), and all the theory I know of places us at the center of the entire Universe, when we consider only the three spatial dimensions (with time being the additional dimension that makes up spacetime, and is not a dimension we can independently move along... which is why we can't actually get to the true center of the Universe, since it would require a time machine).

Thanks, Chris. I love that answer. It has the elegance which, or so I think, is considered the trademark of mathematical solutions that are "true".

Of course not every "elegant" solution is automatically true because of its elegance, but I'm certainly going to use your answer until Art can prove to me, in the sort of language that I can understand, that you have somehow missed the point.

Ann

[Chris Peterson]

This is a cute and rather unique way of thinking, Chris.

But wouldn't you have to include all the space time points that are separated from
the Big Bang by zero space time distance [i.e., s = 0 where ] :?:

I don't think the viewpoint is unique... I think it's mainstream.

Isn't there only one point with a zero distance from the Big Bang: x=0, y=0, z=0, and t=0?

[ErnieM]

Chris wrote:

The Universe is not a three-dimensional structure, but a four-dimensional one. It has a precise center, which coincides with t=0 (the 4D point where the Big Bang originated). In three dimensions, any point can be considered the center, and it is conventional to treat the position of the observer as such. We are definitely at the center of the observable Universe (which is a 3D sphere around us), and all the theory I know of places us at the center of the entire Universe, when we consider only the three spatial dimensions (with time being the additional dimension that makes up spacetime, and is not a dimension we can independently move along... which is why we can't actually get to the true center of the Universe, since it would require a time machine).

Imagine a 100 feet diameter spherical universe an a light bulb at the very center. We all know where the center of this imaginary universe is. A tiny observer, suspended inside the sphere is 2 feet below the horizontal diameter and 80 feet to the left of the vertical diameter. Is the observer at the center of his observable universe?
Now the center light bulb is turned off so the observer can not see the boundary of the sphere. Then imagine 2 pairs of dim lights, each pair in opposite direction inside the sphere. With a laser the observer measures his distances from the dim lights. The observer knows he and the lights are inside the sphere. He has "two" observable universes. The whole sphere and the smaller one bounded by the dim lights. In both, he can compute the "true" centers based on his location in the sphere.

Let us keep it simple. The 20 year it may take for JWST to collect data becomes irrelevant in comparison to the 13 to 14 billion year time scale.[/code]

[neufer]

This is a cute and rather unique way of thinking, Chris.

But wouldn't you have to include all the space time points that are separated from
the Big Bang by zero space time distance [i.e., s = 0 where ]

I don't think the viewpoint is unique... I think it's mainstream.

Reference

Isn't there only one point with a zero distance from the Big Bang: x=0, y=0, z=0, and t=0?

In space time distance is defined by: such that "light cones" replace "points."

Calling the Big Bang the "center" of the space time universe opens up a whole
can of semantic worms (especially as regards the inflationary time period).

In any event, you should know better than to talk about: "x=0, y=0, and z=0."

[Chris Peterson]

Imagine a 100 feet diameter spherical universe an a light bulb at the very center. We all know where the center of this imaginary universe is. A tiny observer, suspended inside the sphere is 2 feet below the horizontal diameter and 80 feet to the left of the vertical diameter. Is the observer at the center of his observable universe?

The problem is, this imaginary universe bears no structural relationship to the actual universe. So without a lot more defining, there's no way to answer the question... and that answer will not help us understand the Universe.

If you create a 3D universe that is analogous to the actual 4D universe we live in, the radial axis is time, and at any particular time, the spatial universe is the surface of the sphere (which is expanding in area, because t is always increasing). So there can be no observer below the surface- "now" is the surface, and that's the only place you can have observers.

An observable universe is any circle on the expanding surface such that none of its interior points are moving away from the circle center at greater than c. There are an infinite number of observable universes, but only one for each point on the surface. If you want to treat the observable universe as a sphere (which it is), you also need to treat the entire universe as 4D- a hypersphere is the simplest case, but not the only one.