-1
$\begingroup$

I don't get it. They telling us that the Webb space telescope will look far away from our home position deep into our observable Universe towards its outer rim about 13 Billion lyrs away where the first protostars and primordial galaxies where formed?

But essentially since our home is at the center of the observable Universe (i.e. observation sphere from our center position) why should these oldest celestial objects in our observable Universe be positioned at the rim of our observable Universe and not remained at the center?

Should not newer matter created on top of older matter like layers of an onion? As the onion grows and expands in space? Does this mean that the expansion of the Universe happened from the rim towards the center?

This is confusing.

$\endgroup$
3
  • 1
    $\begingroup$ Do you know that speed of light is finite? $\endgroup$ Jun 19 at 17:54
  • $\begingroup$ The farthest portions are actually the youngest as we are seeing them when they were newer (in the past). Where we are at now is the oldest (most aged) location in the observable universe. $\endgroup$ Jun 19 at 17:58
  • $\begingroup$ Expansion has nothing to do with it. Even in our galaxy we see the stars farther away at a younger age. $\endgroup$
    – nasu
    Jun 19 at 20:40

2 Answers 2

2
$\begingroup$

While you are right that "newer matter is created on top of older matter", this "newer matter" is not actually what we are looking at!

If we look at a galaxy that is 13 billion light-years away, it means it takes light 13 billion years to reach our telescopes from that galaxy. In other words, our telescopes capture the light that was emitted 13 billion years ago. This is why we "see the past" in some sense: what we see through our telescopes is not what actually happens right now in that region of space, but what happened when the light captured by our telescopes was emitted from that region.

$\endgroup$
1
$\begingroup$

They are positioned at the edge of the observable universe because they have been expanding away from us for the longest possible time.

Note also that new matter is not being continuously formed as the universe expands.

$\endgroup$
3
  • $\begingroup$ That makes sense. So indeed the oldest matter is located at the rim of our observable Universe. Of course due to the finite speed of light we see these primordial matter formations at their youngest age about 13 Billion lyrs ago. I wonder what would be their current actual form? But these is not possible only by S/W simulation projection. I guess Webb will collect enough data to extrapolate their current form. $\endgroup$
    – Markoul11
    Jun 20 at 9:54
  • $\begingroup$ Your answer if correct suggests, that at at the first phases of BB newer matter was created beneath older matter and the whole Universe then inflated "pushing" therefore older matter towards the rim of the observable Universe. That would make the initial BB matter creation before inflation, more like an implosion inward process like an ice cube first freezing at the surface and gradually to the center? After that, inflation followed positioning the oldest matter at the outer layers. Similar to a supernova initial implosion phase followed by an explosion. $\endgroup$
    – Markoul11
    Jun 20 at 10:13
  • $\begingroup$ Please have a look at Weinberg's book The First Three Minutes, it will answer all your questions. $\endgroup$ Jun 20 at 16:51

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.