How does light catch up and pass up when looking in to space

[AJI]

After the recent 'stargazing' programs on BBC they talked about looking 'back in time' and also looking back to the beginnings of the universe.

I fully grasp that light takes time to travel from one point in space to another and when light takes 1000's of years to travel this distance we see the object as it was 1000's years ago.

But this surely breaks down when they say we can look back from our current position in the universe and claim to see far enough to state we are looking at the 'beginnings' of the universe?

With the big bang theory everything was in a singularity which 'exploded' in the timeline shown on the image below..
http://www.universetoday.com/wp-content/uploads/20...

The image above, I'm guessing, should be read as if this shape and events took place in 360 degrees in all directions and not only just the left-to-right diagrammatic that is shown.

So if all 'matter' was originally in a singularity and there was a rapid expansion, and the speed of light has a finite value with 'C' at its maximum in a vacuum, then why hasn't all the light passed the material that formed the earth in the early stages of the big bang?
The way they say on TV that we are able to look back in time suggests that the earth (or the material that formed the earth) was able to travel faster than light and we are now able to wait for the singularity events and the light emitted from it to catch us up....allowing us to view it as it passes the earth.

If I explain it like this..... say for example a TV station existed at the time of the big bang and was located at the singularity.....and aired a single episode of Eastenders, it is a case of the material that formed earth having to travel/expand faster away from the singularity than the EM signal of Eastenders in order we can wait for it to arrive at a later date?
And then if we had a telescope powerful enough we could then watch/receive this particular episode of Eastenders?

If this is true then faster than light speeds are possible no?


Or is something else happening? <--I'm guessing this!

[AJI]

I've heard of this 'inflation' explaination before, but still find it hard to see how this is different to having matter increase its distance from the singularity and that light still has to travel this distance.

[AJI]

Yeah this is what I thought.....it comes back to the thought experiment of - if you were in a spacecraft travelling at light speed....looking ahead would you see light at twice the intensity?...answer = no....also if you were to look behind you, would you see no light as it is unable to catch you up?....answer = no.
What you would see is light with different wavelengths. (please correct if wrong)


But going back to the original question.....so light took 'x'million years to form, and by this time both light and the matter that formed the earth would be 'x'billion kms away from the singularity of the big bang.
So the matter that started emitting light would be at a similar distance from the singularity to that of the matter that formed the earth. <--(assumption made - please correct if wrong).
So as soon as the first light was beginning to be emitted, this would travel at light-speed away from this matter and surely also pass the matter that formed the earth.

So why are we looking 'inwards' towards the centre of the universe to try and see light which should surely be heading away from us that probably passed us 'x' billion years ago?

[AJI]

philis said:

OP: great question!

Also If the static we hear on the radio is the microwave backgound and the remenants of the big bang, and microwaves are part of the electro magnetic spectrum, then why cant i tune my tv in and sit down and watch the big bang?

Thanks


After finding out that light only started being emitted after 'x' number of years I wish I had used the wording of 'radiation' rather than 'light'.

Scientists state they can see the beginnings of the universe if they have a telescope powerful enough, but even after the 'inflation' terminology I still can't see how this 'radiation' can still be 'behind' us in the expansion away from the big bang singularity.

I know cosmic background radiation is all around us and is coming from all directions....but i guess I have to know more about this 'inflation' concept to understand why looking 'behind' us (in the direction away from the singularity) we can still see light-speed EM waves from the singularity catching us up.

[AJI]

With reference to the last couple of posts ....some may find this intersting:
http://www.scaleofuniverse.com/

[AJI]

Thanks for the replies on this subject.
Explaining the 'inflation' theory in simplified terms is helping a lot.

With the 'twisty road' analogy I can easily 'see' how that works in space-time in that 'distance' can be quickly formed irrespective of initial 'separation'.

I've been trying to read up on a few things, and would it be true to say that as cosmic background radiation is approaching us from all directions that there is no real direction to point a telescope to say that it is pointing towards the 'centre' of the universe?

As cosmic background radiation is coming from all angles and not like a river from its source, then there is no one direction to look to view far enough back in time to be closer to the big bang, in fact you could look in ANY direction to get the 'same' result?

Or have I once again flown off on a tangent?


Also, as the universe is now big enough for light to travel from one side to the other in a time that is longer than the life of the universe, are the TV statements a little misleading, in that what they are saying is that given a powerful enough telescope we can see light that is about the same age as the universe itself, and relating this to the time passed since the big bang?

[AJI]

After another episode of Stargazing last night and also this article in the news;
http://www.bbc.co.uk/news/science-environment-2564...

I wondered if I could ask if it is possible for one to locate where the big bang singularity would have been in our universe when time = zero?

Is it possible to know the direction that each galaxy is moving away from each other galaxy and then reverse these lines to point back to an origin?

[AJI]

mrmr96 said:

The fact that you're asking this question demostrates that you don't understand what happened at the big bang.

You are quite right, I freely hold my hands up and admit I don't understand it.

[AJI]

iacabu said:

Forgive me that this is probably a dumb question...could the big bang theory be wrong?

Well yes, it is a theory, waiting for something to 'trump' it in effect.

At the moment I accept that TBBT fits observations better than other theories describing events and also at the same time with it being a theory, in science, it is something that is there for development or dismantlement etc. depending on what you are working towards within your scientific field/project etc.


I follow that there was a 'battle' between matter and anti-matter and this battle can now be replicated on a small scale at the likes of CERN, and these observations can support TBBT and why there is so much 'empty' space.


My questions in this thread have mainly been towards the speed of light issue. I just can't get my head around it.
I follow the fact that it is a relative thing etc, and this can lead to some strange occurrences, but its the 'inflation' vs 'expansion' part that I struggle with.

Edited by AJI on Friday 17th January 13:17

[AJI]

steve singh said:

.....suggests a possible cyclical cycle of universe, back to singularity ....

Would there be enough mass/energy for a cyclic universe to reduce back down to a singularity/big bang condition?

I thought that the initial 'fight' between matter and anti-matter took out much of the mass present at the big bang, the resultant mass expanding and then compressing under gravity would not return conditions to what they were at the beginning.
Probably having a major oversight of something or other so happily stand to be corrected.

I know energy is conserved (in present laws of physics anyways), but even after the matter/anti-matter battle the resultant energy would not have gravitational effects on the resultant universe would it?

[AA999]

I think this thread conveys some of the misconceptions, but this vid from Veritasium explains things in slightly more Layman terms...
https://www.youtube.com/watch?v=XBr4GkRnY04&li...


The main points to take away are (a) The Hubble Sphere and (b) the universe is (and has always been) expanding faster than the speed of light.