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Physics, Astronomy & Cosmology / Re: Is it possible for the laws of physics to change in time?

« on: 25/10/2019 11:50:41 »

Is it possible for the laws of physics to change in time?
Only if they have a calendar to tell them what they should currently be.
To me, that seems unlikely

Using that argument then space must have a speedometer, otherwise how would know if its accelerating or not?

It seems pretty unlikely that laws of physics don't change over time, Entropy would see to that. I mean, honestly, how can chaos be lawful? You either have a descent into chaos or you dont. What's so special about stupid old energy  that only it should suffer entropy, why shouldn't laws be affected too? Maybe I should be asking a clown this question....?

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Physics, Astronomy & Cosmology / Re: What is the cosmic microwave background?

« on: 16/10/2019 15:52:45 »

Thanks Halc

I love the idea that we're already inside a black hole. omg! 

But inertia means something has set it in motion after one big push - like in a 'newton's cradle' toy (or one big bang), which doesn't fit well for an infinite universe (or does it?)  Also, going by your own reasoning 'it can't be infinite if it has an edge', aren't you then saying that the universe is finite because it is expanding? How can something that's infinite get 'more' infinite? (notice I didn't use any numbers there ) Even the inflating sphere analogy is a finite one because you could conceivably travel around it and get back to your starting point.

I think everything becomes simpler by using the phrase 'effectively infinite' rather than just 'infinite'. But are there any major implications for anything if the universe is one or the other?

(runs off to look up 'dark energy')

wow! Now I understand why the military rely on laser rangefinders rather than using Trig. But wwii Submarine commanders used it successfully to sink ships so trig can't be that inaccurate. On the other hand, I thought red-shift was originally calibrated by linking it to the body's observed distance anyway. I thought redshift only supplied a body's speed-of-retreat rather than its distance, and distance was achieved by calibrating it with known-distance bodies. Could it simply be that the early calibration of red-shifts were less accurate than today's methods?

You guys must have the patience of saints is all I can say

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Physics, Astronomy & Cosmology / Re: What is the cosmic microwave background?

« on: 16/10/2019 09:58:44 »

How can something that's inifnite in size 'expand'?

I suppose it can expand because in an infinite void there's nothing to stop an infinite mass from expanding iniside it.

But wouldn't an infinite mass (or even 'effectively' inifinite) just crumple into itself from its own gravity? What stops it from doing this?

Gravity is a weak force, so expansion must be driven by a strong force. What strong force could that be?

Could any known strong force have an effect over an infinite (or effectively infinite) reach?

sorry - just musing out loud.

While on the topic of 'off the scale'.
Is 'infinite' a usefull measure of anything? Infinite means 'without limit'.
so if you have an inifinite universe expanding, then it implies an infinite void to expand into.
if you have in infinite void then there's nothing to stop you having an infinite number of infinite universes, all expanding, but not even over infinite time will any of them ever encounter each other.

however, could their overall gravity effects be pulling each other into expansion?

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Physics, Astronomy & Cosmology / Re: What is the cosmic microwave background?

« on: 15/10/2019 10:31:03 »

That's an excellent explanation. Thanks very much Janus 

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Physics, Astronomy & Cosmology / Re: What is the cosmic microwave background?

« on: 15/10/2019 00:06:07 »

Well, I just don't understand it... If it is infinite then why all the to-do and palava about "We've calculated the mass of the entire universe and it's been found wanting, and in need of a shed-load more mass, which just happens to be invisible" (Dark Matter). It's this statement that inspired me to question what CMBR actually is and why somebody thought it suggested there wasn't enough of it (mass that is).

Is dark-matter another myth that's been blown out of proportion?

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Physics, Astronomy & Cosmology / Re: What is the cosmic microwave background?

« on: 14/10/2019 19:34:18 »

oh...

so the universe was infinite even at only 380,000 years old? That's where I've been going wrong then   

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Physics, Astronomy & Cosmology / Re: What is the cosmic microwave background?

« on: 14/10/2019 17:51:56 »

Halc, we're in agreement on this. So let me put it another way.

Imagine the post-opaque plasma universe from which the CMBR comes from.
For arguments sake it's close to the end of the plasma era.
Imagine you can locate the plasma which is destined to form our galaxy.
imagaine you can locate the same for the Andromeda galaxy.
For arguments sake lets say the two 'clumps' are ten light years apart.

There is another plasma clump 100 million light years away
A fourth clump 101 million LYs away

FREEZE TIME.
The andromeda plasma's photons will pass our plasma galaxy after 10 years (forget about inflation).
The 3rd and fourth clumps will go past us after 100 & 101 million years.

UNFREEZE TIME
add inflation
Andromeda's plasma photons go past ours galaxy's plasma after 10 * (inflation rate) years - or well before their stars even form.
group 3's photons take 13.4 BY to reach us (what we can detect right now)

logic says we wont see group 4's photons for another 1 million * (inflation rate) years (or apparently we can with just a bigger telescope  )
but if we were able to detect those photons they would have a longer red-shift than group 3's.

if we knew what the inflation rate was we'd be able to work backwards and know exactly how far group 3's plasma was away from our galaxy's plasma in the plasma usiverse, and have some idea of the size of the universe back then.

If we compared the red-shift difference between group3 & group4 photons we'd be able to say that group4 was 1 million lights more distant than group3 so we'd know the plasms universe was AT LEAST 1 million light years in diameter.

All I'm trying to find out is (haha) how big the early plasma universe must have been to make photons take 13bn years to reach us, modified of course by the inflation rate.

not a very good what-if perhaps, but I'm new to this.

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Physics, Astronomy & Cosmology / Re: What is the cosmic microwave background?

« on: 14/10/2019 15:32:02 »

If it was generated from one small area in a small time, it would appear to us as a flashbulb on a camera going off at one random instant in time.  It would only be noticed if 1) There were humans around at the time,

The CMB was emitted from everywhere, all at once, and as I said before, all of the CMB today comes to us from some identical distance.  If the light was emitted closer by, it has already passed by us, and if emitted from further away, it hasn't reached us yet.

According to the Big Bang model, the radiation from the sky we measure today comes from a spherical surface called the surface of last scattering. This represents the set of locations in space at which the decoupling event is estimated to have occurred[15] and at a point in time such that the photons from that distance have just reached observers

Sorry, but the above means I have to ask my question 'again'
Why the 13bn delay in the CMB reaching us?

It isn't like the big bang was an event that happened 'to somebody else'. We were there when it happened. We were in the middle of it. We've been part of the inflation, and it seems photons travelling at the speed of light from that place where we started from have only just caught us up... HOW?

I dont expect an answer because it seems everybody has a different 'explanation'.

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Physics, Astronomy & Cosmology / Re: What is the cosmic microwave background?

« on: 14/10/2019 13:06:33 »

thanks for the video

It wasn't the easiest explanation to follow as he seems to keep drawing on a level of knowledge in his listeners that I don't have, and I seemed to miss a lot of patches in his theory. The death of one universe being the birth of another... with the implication of photons being the common denominator in the deaths and births of universes, and the evaporation of black-holes supplying the energy for the new births (eek).

But a really fascinating idea, and one which would seem to explain a high entropy universe evolving (or devolving) into a low "boring" one before its rebirth (low entropy because everything is so dispersed that there are no more configurations available).

But this is why I asked the question about red-shift fluctuations in the CMBR. Wouldn't a uniform red-shift indicate the CMBR was generated from just one very small area and time? There should be CMBR from the moment when space lost its opacity, and CMBR from the time when it stopped radiating and started 'forming'. Surely between these two periods the redshifts of the CMBR would have increased due to the intervening inflation? A uniform redshift suggests a sudden burst of energy from a flat surface!

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Physics, Astronomy & Cosmology / Re: Is light an independent entity, or is it an effect of a larger mechanism ?

« on: 14/10/2019 07:30:46 »

Is this a good time to ask about something I came across recently in a popular science video somewhere....

Concerning a particular type of particle which, when its 'state' was changed then a matching particle's state also changed - instantaneously, no matter how widely seperated in distance (thus appearing to break the lightspeed limit).

Sorry I forget the details and the video, because I didn't pay too much attention to it. But just wondering if this rings any bells here?

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Physics, Astronomy & Cosmology / Re: Was the Big Bang the beginning of the universe?

« on: 14/10/2019 06:56:21 »

Deciding how the universe came into existence is one question.

Deciding if the universe exists at all is another one. Existence is an effect. What is the cause? There is nothing concrete that I can pick out from 'popular science' (as opposed to hard science from the scientists' workbench) that points to anything you can put your finger on as saying 'this is the building block for everything'.

There seems to be no current detectable limit to the external universe, and no current detectable limit to the inner universe of microphysics. Like a mandlebrot pattern, the physical universe seems to have unlimited granularity. I like to think that the search for physical unification is like looking for the simple underlying formula for mandelbrotian chaos .

I like the quote from 'Hitch-hiker's guide to the Galaxy'

"There is a scientific theory which states that the moment we understand the universe around us it will instantly be replaced by a more complex one... There's is another theory which states that this has already happened."

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Physics, Astronomy & Cosmology / Re: What is the cosmic microwave background?

« on: 14/10/2019 05:46:19 »

In a way it's a mystery HM. What we see is 13.8~ billion years away from us. That's the time of light existing. When it comes to the universe itself it may be infinite though. We have our 'bubble' of light and as we 'move' through the universe that 'bubble' still won't grow. One reason why there is no definite 'place' for the universe to start, although we still set a 'time' to it locally defined.

If the universe (during the period of its CMB emition) was infinite, then wouldn't there be evidence of it in its red-shift? Wouldn't there be quite a large fluctuation in red-shift values for the CMB?

Is it possible to determine the size of the CMB universe from its red-shift fluctiaions? Assuming that it had a physically recognizable 3 dimensional shape...

and assuming that it has red-shift fluctuations.....................................

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Physics, Astronomy & Cosmology / Re: What is the cosmic microwave background?

« on: 12/10/2019 20:06:20 »

I'm asking if there's a reason (yet) for this 13bn year delay in the cmb reaching our neck of the universe.

There's no delay.  It was always here, and will always be here, since the light is everywhere at all times.  We're just observing from a position where it has been 13 billion years since that light first flooded all space.

haha. OK. Enough questions I think.

Many thanks

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Physics, Astronomy & Cosmology / Re: What is the cosmic microwave background?

« on: 12/10/2019 17:44:58 »

Apologies Colin for the confusion.

I'm asking if there's a reason (yet) for this 13bn year delay in the cmb reaching our neck of the universe.

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Physics, Astronomy & Cosmology / Re: What is the cosmic microwave background?

« on: 12/10/2019 12:37:20 »

Thanks everybody for the explanations

They all make perfect sense and fit in with the logical laws of physics as I understand them. But there's still my original question that even now I cant get my head around.

I'll come back to it in a moment, because evan_au mentioned that the early universe was opaque due to the ultraviolet radiation. I must have misunderstood him because otherwise the universe would still be opaque due to ultraviolet radiation wouldn't it (or at least the more distant/older swathes of it would still be opaque?)

But forgetting that, I still dont understand WHY anything as old as 13bn years is still visible to us. The only way I can understand that is if the universe as early as one hour old (just to pick a sensible timeframe) was already as big as our visible universe now is, big enough so that anything travelling at lightspeed would still take 13bn years to travel between two given points in it.

If it wasn't already this big then common sense would sugest that  its expansion rate (in order to explain the 13bn year 'lag') would be too high for gaseous material to coalesce into stars and solar systems.

So was the Universe already universe sized very early in its life?

Have I just answered my own question...? (other than the ultraviolet bit).

Many thanks

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Physics, Astronomy & Cosmology / Re: What is the cosmic microwave background?

« on: 12/10/2019 01:27:54 »

Now I'm interested again, with more advanced questions, if that's allowed.

The conversation seems to imply the CMB generation was quite a short phase (when the universe was a 3000k plasma). If its effects are still saturating the universe after 13.7bn years (due to its photons filling cubic meters of space as fast as they leave it), then the volume of this plasma must have been.... 'large'. But, why dont we see other radiation that must have been emitted before and after this 3000k period? Why isn't this still filling up cubic meters of space as fast as they leave it like the cmb? Or is this the dark matter that ppl are still looking for?

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Physics, Astronomy & Cosmology / Re: What is the cosmic microwave background?

« on: 10/10/2019 00:06:53 »

This is just going around in circles....

What wasn't clear about what we said?

the statistics :p

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Physics, Astronomy & Cosmology / Re: What is the cosmic microwave background?

« on: 09/10/2019 13:09:37 »

This is just going around in circles....

I'll just agree with the experts that they really do know how much mass is in the universe and that it just isn't enough, and that invisible matter really does exist (along with flying broomsticks and invisible cloaks).

Thanks everybody for their patience and attempts to explain something that only really exists in mathematics.

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Physics, Astronomy & Cosmology / Re: What is the cosmic microwave background?

« on: 08/10/2019 23:16:58 »

It was formed when the first atoms formed. The bonding of an electron with a proton to form a hydrogen atom releases a photon. Those protons and electrons very uniformly filled all of the Universe, so the radiation was released from pretty much all locations in space, both near and far.

But I didn't think there was a 'far'! Wasn't all matter/energy compresseed in a high pressure / high temperature 'soup' in which the first atoms were able to bond? How can they bond in a cold / empty envrinment?

Are we even talking aboout the same thing anymore?

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Physics, Astronomy & Cosmology / Re: What is the cosmic microwave background?

« on: 08/10/2019 21:00:13 »

I suppose my next obvious question has to be what has generated (or is generating) the CMB?

It must be more than from just the birth of everything...? For so much radiation to still be zipping passed us after so long, then whatever radiated the photons we're still seeing surely must have been a long way from where 'we' were at the time it was emitted.

Does that suggest the possibility of calculating the diameter of the universe at a particular moment in history? I mean, if it's possible to calculate how much total mass the entire universe holds by investigating the CMB, then why not be able to calculate how big it once was also...