What is the Universe expanding into..

[system7]

Doctor Mansfield's failing, in retrospect, was that he was an unconfident and shy man. Highly autistic.

But presented a terrific lecture on Magnetocrystalline Anisotropy. An interesting subject.

Magnetocrystalline anisotropy - Wikipedia

After our first botlle of liquid Helium seemed to disappear into thin air, he should have stepped in and said "Hold it, partners, we need to re-evaluate things."

Naturally as a student noob in those days, I bowed to his Wisdom. But in retrospect, I should have taken charge.

 

[Disco-Pete]

After our first botlle of liquid Helium seemed to disappear into thin air,

Did you make a tribute to the chipmunks?😀

 

[KaffiMann]

But in retrospect, I should have taken charge.

Hindsight is always 20/20.Or, perhaps at least sometimes.

 

[N101N]

What is vacuum? Well, the ideal vacuum would be completely devoid of any matter.

Idealism belongs to mathematics. Empty space would be purposeless, energy transfer would not be possible and the Universe would not exist. Discontinuity is not allowed in Nature. The interstellar medium has had many names during the centuries. I strongly dislike the name vacuum, it reflects an unphysical view, the view of a bunch of mathematicians.

Vacuum is a volume with lower density of mass. There is more distance between the fragments of matter, but there is still matter.

Hey, this is beautifully said! Atomic matter comprising massive, highly compressed, hard nuclei makes up a much more dispersive and slower medium.

 

[Disco-Pete]

Absolutely spot on. Although the particle density may be low, the humongous volume of space means there is an unimaginably large number of matter particles floating around out there!

So how is it that the light we see coming from 13 billion years ago from a distant star or galaxy is visible? How much of it has been absorbed along the way? How much would a section of space from here to there have to be compressed to render it's particle matter a solid wall and how thick would that wall be?

 

[Bonsai]

Idealism belongs to mathematics. Empty space would be purposeless, energy transfer would not be possible and the Universe would not exist. Discontinuity is not allowed in Nature. The interstellar medium has had many names during the centuries. I strongly dislike the name vacuum, it reflects an unphysical view, the view of a bunch of mathematicians.



Hey, this is beautifully said! Atomic matter comprising massive, highly compressed, hard nuclei makes up a much more dispersive and slower medium.

Funny thing is EM works most perfectly in a total vacuum. You don’t need particles of any description for EM to propagate between point A and point B. Nowhere in Maxwell’s equations is any of this required.

(Not looking for a fight, but these are the facts - and the theory works!)

🙂

 

[Galu]

So how is it that the light we see coming from 13 billion years ago from a distant star or galaxy is visible? How much of it has been absorbed along the way?

I covered this in post #5344 when I gave this explanatory link:

Cosmic Calorimetry or: How I Learned to Stop Worrying and Love Hydrogen - Ideas | Institute for Advanced Study

While Gunn and Peterson found that intergalactic space was mostly transparent, as telescopes got bigger and bigger and instruments could take finer and finer spectra, it was realized that there was absorption, but it was concentrated in narrow lines corresponding to concentrations of neutral hydrogen. This pattern of narrow absorption spikes was subsequently called the Lyman-alpha forest owing to its appearance in the observations.

 

[N101N]

Bonsai, maybe you could explain how forces are transmitted in a total vacuum.

 

[Galu]

How much would a section of space from here to there have to be compressed to render it's particle matter a solid wall and how thick would that wall be?

If intergalactic space were compressed to into a hot ball of plasma the size of our galaxy, then photons would be scattered in all directions by the sub-atomic particles in the plasma and would effectively be unable to progress in any one direction through the plasma.

 

[Disco-Pete]

@galu, I just meant hypothetically bringing into close proxitmity to get a picture of the sub atomic particle count in space, not chemically.

 

[Galu]

Bonsai, maybe you could explain how forces are transmitted in a total vacuum.

Physicists don't actually claim to know how forces can propagate through a vacuum.

Such forces can only be described in terms of mathematical artifacts.

However, the ability of EM waves to travel in vacuum is a fact.

 

[Galu]

@galu, I just meant hypothetically bringing into close proxitmity to get a picture of the sub atomic particle count in space, not chemically.

If I could figure out what you actually mean, I might be able to answer your queries more succinctly! 😀

 

[indra1]

However, the ability of EM waves to travel in vacuum is a fact.

Ditto with gravitational waves.

 

[Galu]

How much would a section of space from here to there have to be compressed to render it's particle matter a solid wall and how thick would that wall be?

@galu, I just meant hypothetically bringing into close proxitmity to get a picture of the sub atomic particle count in space, not chemically.

Sorry, I can't quantify that hypothetical thickness - it would involve me spending a great deal ot time amalagamating data and performing mathematics! 😱

An externally hosted image should be here but it was not working when we last tested it.

 

[Disco-Pete]

I know, I'm not exactly stupid🙂
Why do you think I asked you??😀
In a guesstimate, a LY?

 

[Galu]

Your t-shirt is on its way!

 

[Disco-Pete]

That's very generous of you but it was a sincere question.


So, a LY?

 

[Bonsai]

Bonsai, maybe you could explain how forces are transmitted in a total vacuum.

I never mentioned forces. I spoke about EM. An EM wave impinging on a conductor in a total vacuum will cause electrons to flow in the conductor.

However, if you arrange two conductors correctly next to each other then this EM wave will cause electrons to flow in both conductors and they will experience a force between them.

 

[system7]

I think we need radical ideas to get out of the total baffling mess that is modern Physics.

I have noticed that what is really quantised is SPIN. Therefore we need SPIN-friendly units.

Enter the ancient Sumerians, doubtless visited by a Flying Saucer form some more advanced but benevolent species. I mean, even the Sumerians would have gone for Base 10 unless enlightened:

Sumer - Wikipedia

Sexagesimal, also known as base 60 or sexagenary is a numeral system with sixty as its base. It originated with the ancient Sumerians in the 3rd millennium BC, was passed down to the ancient Babylonians, and is still used—in a modified form—for measuring time, angles, and geographic coordinates.

The number 60, a superior highly composite number, has twelve factors, namely 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, and 60, of which 2, 3, and 5 are prime numbers. With so many factors, many fractions involving sexagesimal numbers are simplified. For example, one hour can be divided evenly into sections of 30 minutes, 20 minutes, 15 minutes, 12 minutes, 10 minutes, 6 minutes, 5 minutes, 4 minutes, 3 minutes, 2 minutes, and 1 minute. 60 is the smallest number that is divisible by every number from 1 to 6; that is, it is the lowest common multiple of 1, 2, 3, 4, 5, and 6.

I like it. Along with Mr. Bonsai's Motion Mountain: Motion Mountain - The Captivating Free Physics Pdf Book

How hard can it be? 😀

 

[Bonsai]

I have the whole lot on my iPad. Great introductory text IMV!