Limit of light travel time

[spurius]

I dont believe the universe was born about 14 billion years ago. AFAIK they base the age of the universe on how far they can see. The most distant object they detected is a few miles short of 14 billion light years away. Imo this is just a matter of luck. There isnt much that is likely to last for 14 billion years. There is even less chance of a sufficient amount of light from a particular source that could travel 14 bly without being blocked or what ever. 

Also if the universe was expanding from a single point, then wouldnt the observable limits vary in distance depending on the direction you looked? Unless ofcourse we are near the centre of the universe.

If the whole universe appeared out of nothing then why doesnt another one spontaneously appear right in front of you like a nutcase in a car?

[jambouk]

30 billion light years away....

http://m.bbc.co.uk/news/science-environment-24637890

It's complex. I don't understand any of it!

Jd

[Steve Ward]

Time you had a bit of a trawl through the relative subjects on wiki methinks ...    

And those cars only 'spontaneously' appear in front of you when you're going too fast and not looking where you're going ...   

[AstroJon]

There are rumours that detection of gravitational waves from the inflation period will be announced on Monday, if so this will help explain why the universe is much bigger than 14 billion years.

The observable limit depending on your location assumes that space-time is flat, if not then it gets rather complicated. The age of the universe has been fairly well defined in recent years from multiple methods with what I consider to be a quite remarkable degree of accuracy considering.

As for the origin of the big bang, a car 'spontaneously' appearing in front of you wouldn't be 'spontaneously' appearing out of nothing, it would appear out of air, in space. Air and space which has well defined physical properties. Nothing implies nothing, no space or time exists. Understanding the origin of the big bang will be difficult for us to comprehend, by definition it has to occur outside of the universe, outside of space and time because they didn't exist when the big bang happened.

[HumptyMoo]

There is a lot of evidence to suggest that what we are being told is correct. The observations made are generally repeatable and in some cases even debunked by the same people that suggested them. Science doesn't have "The answer" but given the collective intelligence that agrees with the findings I am not one to declare "Shenanigans!"

However, I still think if you have the mind set to challenge opinion and observation then do so. I believe that science encourages this, although, scientists will sometimes scoff and laugh until proven beyond doubt, challenges to popular scientific thinking.

If you don't accept it, that's cool beans, to refute it though, get some proof (it's all the rage in science ).

Belief is another matter, but that's for a discussion elsewhere on the intrawebberz

[AstroJon]

Ugh, remove the word "ago" from the end of the first sentence and that might make more sense.

[voidhawk]

AFAIK they base the age of the universe on how far they can see. The most distant object they detected is a few miles short of 14 billion light years away. Imo this is just a matter of luck. There isnt much that is likely to last for 14 billion years. There is even less chance of a sufficient amount of light from a particular source that could travel 14 bly without being blocked or what ever

Sort of, 14BY is the distance to the opaque wall of radiation left by the Big Bang, when corrected for the expansion of  the universe. There's a chance that the universe could have been around longer, but the conditions which make for an omnipresent field of energy wouldn't last long. The Cosmic Microwave Background is all around us and can't be blocked in all directions by the intervening matter.

Also if the universe was expanding from a single point, then wouldnt the observable limits vary in distance depending on the direction you looked? Unless ofcourse we are near the centre of the universe.

This was something which took me a long time to wrap my head around The standard 'the universe is a balloon' model didn't do anything for me. The 'simplest' way to describe it is to imagine the universe as the image below. It isn't just the objects within the universe expanding but the universe itself. The green dots represent the galaxies in a  universe at a moment in time, the red dots at a later time after the universe has expanded. If you pick any one galaxy from point A and superimpose image B over it, you'll see that all the galaxies seem to be moving away from you, making it appear, from your perspective, that you are the centre of the universe, but as images C and D show, it doesn't matter which dot you pick, they ALL look like they're the centre of the universe.

You can either say that the universe has no centre, or that everywhere is the centre.

If the whole universe appeared out of nothing then why doesnt another one spontaneously appear right in front of you like a nutcase in a car?

There are two answers to this, firstly, we are inside the universe. Another nutcase in a car doesn't just appear in your passenger seat (unless you've had too much to drink to drive!)

The second answer is more complicated but bear with me.

Nothing, in quantum mechanical terms, doesn't exist. If you measure the spaces between particles, you find that instead of a total vacuum, you find a boiling sea of virtual particles popping in and out of existence, seemingly from nothing. If you want to read up more on this, look up 'quantum foam' or 'The Casimir effect.' In our universe, these small disturbances don't add up to much, but in the early universe, prior to expansion, a tiny disturbance led to a massive imbalancing of energy which is why we're here to talk about it.

I'm just an enthusiastic amateur, but Ethan Siegel can explain it far better than I can -- with maths!

http://scienceblogs.com/startswithabang/2009/08/13/what-makes-the-universe-expand/

[Knight of Clear Skies]

Another recommendation for Ethan Siegel here, he explains things very clearly. This article lays out the evidence for the Big Bang very neatly.

I dont believe the universe was born about 14 billion years ago. AFAIK they base the age of the universe on how far they can see. The most distant object they detected is a few miles short of 14 billion light years away. Imo this is just a matter of luck. There isnt much that is likely to last for 14 billion years. There is even less chance of a sufficient amount of light from a particular source that could travel 14 bly without being blocked or what ever. 

Also if the universe was expanding from a single point, then wouldnt the observable limits vary in distance depending on the direction you looked? Unless ofcourse we are near the centre of the universe.

There are some popular misconceptions about the Big Bang, most people think it's a theory which explains the creation of the universe. In fact it only covers its (very) early history and subsequent evolution. The theory is based on the observation that nearly all galaxies are moving away from us. If you run that backwards it implies that the universe must once have been in an extremely dense and hot state. It makes two key predictions: the existence of the afterglow (the CBM) and the composition of the early universe (hydrogen, helium and a dash of lithium, once it cooled enough for matter to form). The signal from the CBM can be seen by pointing a radio telescope at any point of the sky, and spectroscopy tells us what elements are emitted that light. The spectrum exactly matches the predictions of the Big Bang.

There are no absolute certainties in science, perhaps there is some other theory we haven't thought of which explains all this. However, in practical terms the Big Bang is scientific fact: it explains the CBM, the abundance of elements that make up the universe and its expansion, which is quite an achievement. There are plenty of things it doesn't cover, such as the actual origin of the universe.

If the whole universe appeared out of nothing then why doesnt another one spontaneously appear right in front of you like a nutcase in a car?

Perhaps one could, but we'd be blotted out of existence before we knew about it. We don't know if the creation of our local universe was a unique event. There are some good reasons to think we might be part of a multiverse (which may or may not be infinite), but this is theoretical, and we may never be able to work out whether this is the case.

[Ptarmigan]

There is a big problem right at the beginning of the first post,

"I  , , , believe",

science isnt good at that.

[ronin]

Part of the problem is you are talking in one unit of time and another of distance.

The distance we can observe is owing to the way the maths works and the units used the same numerical value 13.7 billion.

I suppose that using a time unit of 1 year and distances of lightyears makes it very easy to mess up the two. Maybe easier to say the universe is 13.7 billion years old and the observable distance is 4.2x10⁹ parsecs, now you have a time of one value and a distance of another.

There is still lots of stuff beyond the distance of  4.2x10⁹ parsecs distance that we cannot see.

The space between us and it is simply expanding faster then the speed of light, so the light cannot get here, so we never see it and so there is an observable limit.

Go learn about it, it is great fun, turns your brain mushy and you start to get an idea of strange way our little lump of space-time does things.

[Myopicus]

The distance we can observe is owing to the way the maths works and the units used the same numerical value 13.7 billion.

I suppose that using a time unit of 1 year and distances of lightyears makes it very easy to mess up the two. Maybe easier to say the universe is 13.7 billion years old and the observable distance is 4.2x10⁹ parsecs, now you have a time of one value and a distance of another.

There is still lots of stuff beyond the distance of  4.2x10⁹ parsecs distance that we cannot see.

The space between us and it is simply expanding faster then the speed of light, so the light cannot get here, so we never see it and so there is an observable limit.

Yup, brain has turned to mush.  Faster than speed of light expansion?  Not heard of this before (other than Big Bang).  Do you have any link that might explain this and possibly stop my head hurting so much?

[Knight of Clear Skies]

Yup, brain has turned to mush.  Faster than speed of light expansion?  Not heard of this before (other than Big Bang).  Do you have any link that might explain this and possibly stop my head hurting so much?

This minute physics video may help:

[BargeGazer]

Another +1 for Ethan Siegel from me.  He has the knack of making the marginally understandable clear and the totally baffling interesting.  https://medium.com/starts-with-a-bang.

And his Messier Monday series is of relevance to any of us interested in the catalog objects.

David

[Kropster]

Just because you don't believe something, doesn't mean it isn't true.

I prefer to take heed of what people who have spent a lifetime studying these things have to say rather than go on a feeling I might have about something.

Nothing is certain and all we can do is work things out based on the observations we make.

[Steve Ward]

And don't you just love folk who post things like this and don't even return to the forum to follow their thread 24hrs after posting it , think there's a name for them .... 

[Pig]

Part of the problem is you are talking in one unit of time and another of distance.

The distance we can observe is owing to the way the maths works and the units used the same numerical value 13.7 billion.

I suppose that using a time unit of 1 year and distances of lightyears makes it very easy to mess up the two. Maybe easier to say the universe is 13.7 billion years old and the observable distance is 4.2x10⁹ parsecs, now you have a time of one value and a distance of another.

There is still lots of stuff beyond the distance of  4.2x10⁹ parsecs distance that we cannot see.

The space between us and it is simply expanding faster then the speed of light, so the light cannot get here, so we never see it and so there is an observable limit.

Go learn about it, it is great fun, turns your brain mushy and you start to get an idea of strange way our little lump of space-time does things.

This is the way I understand it and.... just to make it a tad more brain mushing.... what we are expanding into isn't there until we are in it    

[Pig]

And don't you just love folk who post things like this and don't even return to the forum to follow their thread 24hrs after posting it , think there's a name for them .... 

Maybe he spontaneously appeared yesterday

[HumptyMoo]

Maybe he spontaneously appeared yesterday

Which would suggest he was then immediately annihilated