Looking Into Deep Space & Back In Time. How does it work?

[boxerTen]

hornet said:

My understanding was the photons in the early universe were "trapped" in a sort of high energy "soup" and were only released once things had cooled to a certain point, allowing them to break free? Sort of similar to the how the light we see from the Sun is made of photons that have spent thousands of years migrating to its surface?

Essentially that's correct. The early Universe was opaque, light didn't propagate any significant distance, instead it got scattered off the charged particles (electrons and Hydrogen and Helium nuclei) that each flew about freely and together constituted a hot plasma. It was only when the plasma of free electrons and free atomic nuclei cooled enough to condense together into neutrally charged atoms that the light ceased to be scattered - whence the Universe became transparent, circa 380,000 years post big bang.

[boxerTen]

Blib said:

AJI said:

But the thing I still can't get my head around is that when they say with more and more powerful telescopes they can see further and further back in time and can see closer and closer to the big bang origin.....does this mean with a powerful enough telescope yet to be developed that they could in theory see back to the singularity itself (or read that to be the very first EM wave transmission after the big bang) ???

That's part of my issue with all of this.

The Universe was an opaque plasma for its first 380,000 years so regardless of the power of one's telescope the best that is possible is to see back to this fog. In fact that is precisely what observations of the cosmic microwave background are - a view of the fog.

The Universe was not opaque however to gravitational waves, so when we sort out how to observe them, it ought to be in principle possible to look back to within fractions of a second of the big bang.

[khushy]

I am fascinated by all this science gibberish but do you really think that we know what happened billions of years ago - lets face it - man (we men) has trouble remembering what happened yesterday yet alone last week + the stories we concoct to get us out of trouble for not remembering what happened far out weigh the st that most "scientists" come up with about our origins.

We are here, life is short, you will die, stars (if thats what they are) are beautiful, allwomenarenuts and petrol is running out - that's about all you can be absolutely certain of!



khushy

[mattnunn]

So you can listen to this about the Father of the Big Bang theory, who as it happened was a Catholic Priest.


http://www.bbc.co.uk/iplayer/episode/b01jmtxt/Fath...

[Einion Yrth]

Bedazzled said:

I think one could say a photon is omnipresent.

I have, half seriously, on occasion argued that THE photon is omnipresent.







(all hail the Photon).

[AJI]

Well I generally consider myself to be of scientific thinking, I am an engineer after all !
But for now I am just going to have to accept that I don't know enough about the fundamentals and probably some of the finer details about space-time to be able to get my head around the question arising from the OP.

There have been some good replies on this thread and nicely written too, but still, I have more questions than answers and I am now going to bow out of this thread before I show myself up

[Gene Vincent]

hornet said:

Gene Vincent said:

Plus, for a photon there is no time at all, there is simply space and that is compressed to an instant also, its life, its journey, its entirety is compacted to an instant.

This is the one thing I've always struggled with. I'm sure the equations can prove it, but I just can't get my brain round it. If a photon feels no time, yet we say it has taken 13 billion years to reach us, what exactly has the photon experienced on that journey? Indeed, is it even valid to describe it as a journey in the first place? What does the universe look like from "Johnny Photon's" point of view?

Too late to be thinking about this stuff!

You are not alone, it is a stumbling block for many.

Events along the path of a photon are simultaneous and and its path is coterminous, it doesn't seem to interact with itself.

Even gravity acts on gravity!

Unlike all the other elements of the Cosmos, which can effect each other and like elements, a photon appears to not do so, this does give good source material to claim there is but one photon in the entire Cosmos.

This is categorically wrong and quite easily proven and shown even without the PHOJET Projects work, but you need a reasonable knowledge of probability arrows and clocks, it takes all of about 1 second for someone who understands these shortcuts to immediately grasp the reasons for the lack of interaction and it's rather prone to little gasps of delight in lectures as a toothy problem of their past disappears in an instant.

That can be rewarding.

[Gene Vincent]

AJI said:

...I have more questions than answers and I am now going to bow out of this thread before I show myself up

If that meant disbarment from discussions I'd never be in any debate in this field, my head is filled to overflowing with questions to which there is no answer at the moment, don't feel over-horsed or inadequate, it goes with the territory, those two are my constant companions and taunt me, poking their tongues out and blowing raspberries at every turn.

We are all in the dark to some extent, ask questions, it is also good for those further into the darkened room to retrace their steps back to you and ensure the trail they have been blazing in their thoughts isn't a false one.

It is why anyone serious in this stuff lectures as well as just sits and thinks.

[Gene Vincent]

Bedazzled said:

Gene Vincent said:

In the 13.7 billion years since the settled period began the Cosmos has grown along with the speed limit.

I'm struggling with this part as I stumble about in the dark room; distant galaxies are still moving away from us faster than light despite the physics being 'settled', i.e. the speed limit does not apply to inflation. But what is it that is inflating?

because you are looking back in time, to when it was expanding at that rate, it is confirmation of the inflation.

[ewenm]

Bedazzled said:

I don't think that's correct, look at the calculation I posted above; that distant galaxy is currently moving away from us at 2.2x the speed of light. The rate of expansion is also increasing.

How do we determine what the distant galaxy is doing now given the length of time it takes information to reach us? Is it extrapolation of past behaviour?

[davepoth]

My take on it:

The speed of light is a constant of a distance travelled in a period of time. The proportions of that constant remain the same from a given point of reference, however we can see examples in space (notably black holes) where distance and time get skewed. From a point of reference next to a black hole the speed of light still looks like the speed of light, but if we could see it from our point of reference it would look very different.

[Gene Vincent]

Inflation occured very soon after the Big Bang, within the first second of the Universe.

The expansion of the Universe is unrelated to inflation... inflation was an extra boost on that expansion... it is likely that Inflation and the acceleration of the expansion are related, as these are very similar in nature.

The field responsible for driving Inflation the Inflaton field, but the field for driving the acceleration is Dark Energy.

It's marginally possible that these could be the same field, behaving with very different energy scales at different times in the Universe.

The more distant a galaxy is from your point of measurement, the faster it will appear to be accelerating because spacetime is highly curved at cosmological scales.

In an observational sense, it could appear to be exceeding the speed of light, meaning that one galaxy can't be observed from the other galaxy.

But that doesn't mean it's violating the speed of light in a physical sense.

[qube_TA]

Eric Mc said:

So, the speed of light is increasing too.

It's not just the distances that are increasing - but the items we use to measure the distances are increasing. The measuring stick is stretching as we try to use it to measure.

This!

[ewenm]

qube_TA said:

Eric Mc said:

So, the speed of light is increasing too.

It's not just the distances that are increasing - but the items we use to measure the distances are increasing. The measuring stick is stretching as we try to use it to measure.

This!

But since it is a closed system and everything is expanding, does it make any sense to say distances are increasing?

[mattnunn]

ewenm said:

qube_TA said:

Eric Mc said:

So, the speed of light is increasing too.

It's not just the distances that are increasing - but the items we use to measure the distances are increasing. The measuring stick is stretching as we try to use it to measure.

This!

But since it is a closed system and everything is expanding, does it make any sense to say distances are increasing?

Who says it's a closed system?

It's either expanding into something or something is being compressed somewhere. My 30cm ruler doesn't seem to have expanded in the last few weeks, although I can't be sure how big it was before I got it out the stationary cupboard (stationery).

Which leads to the real truth, everything only really exists as you see it. Our definitions of the universe will die with us.

[ewenm]

mattnunn said:

Who says it's a closed system?

It's either expanding into something or something is being compressed somewhere.

Says who? Have you any evidence for the Universe not being a closed system? As far as I know, we haven't observed any phenomena that appear to be extra-universal. The idea of the universe expanding into something is flawed, and also one of the hardest to let go of.

mattnunn said:

My 30cm ruler doesn't seem to have expanded in the last few weeks, although I can't be sure how big it was before I got it out the stationary cupboard (stationery).

Don't go all Schrodinger's Cat on me, although Schrodinger's Ruler is much less cruel ;0

mattnunn said:

Which leads to the real truth, everything only really exists as you see it. Our definitions of the universe will die with us.

Your truth mattnunn, your truth. Are you suggesting that things we can't see don't exist? As for the last sentence, well yes of course, given that we are the only species we know of capable of making a definition of the universe.

[don4l]

Most people seem to be treating Einstein's theories as if they were immutable laws of nature. They are not. They are just a set of mathematical equations that we can use to describe some of the things that we see around us.

These equations do not work at the sub-atomic level. I strongly suspect that they also don't work on the very large scale either.


Don
--

[mattnunn]

don4l said:

Most people seem to be treating Einstein's theories as if they were immutable laws of nature. They are not. They are just a set of mathematical equations that we can use to describe some of the things that we see around us.

These equations do not work at the sub-atomic level. I strongly suspect that they also don't work on the very large scale either.


Don
--

Einstein didn't believe in any of this stuff, he didn't support the BBT or an expanding universe, he and Fred Hoyle believed in a stable universe, the Big Bang was a term Hoyle used to deride the theory, it stuck. As previously posted the Big Bang theory was first promoted by possibly the worlds best and most forgotten Physicist George Lamaitre, his name not so widely used by popular science due the confusion caused in the minds of the geeks because of the fact he was a catholic priest.

[mattnunn]

ewenm said:

mattnunn said:

Which leads to the real truth, everything only really exists as you see it. Our definitions of the universe will die with us.

Your truth mattnunn, your truth. Are you suggesting that things we can't see don't exist? As for the last sentence, well yes of course, given that we are the only species we know of capable of making a definition of the universe.

If humans aren't agency for knowledge and there is an immutable physical truth to reality that goes beyond our perception, how come we have to think this stuff up before we go looking to see if it's true? Science has long since stopped discovering stuff and really only prooves what our imagination can concieve.

[qube_TA]

mattnunn said:

Who says it's a closed system?

It's either expanding into something or something is being compressed somewhere. My 30cm ruler doesn't seem to have expanded in the last few weeks, although I can't be sure how big it was before I got it out the stationary cupboard (stationery).

Everything inside the universe is spreading out.

However if you could somehow be outside the universe, and also be somehow able to see this one then it's probably not changed size at all.

The age/shape/size of the universe only exists inside it.