Does this explain what generates gravity?

I scored 10/10 (second time around!)

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I looked into the subtleties surrounding energy conservation in general relativity in order to put some flesh on the subject.

Underlying energy conservation is the notion that physical properties and laws don’t evolve with time.

That may be true on Earth.

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However the distance between any two cosmic objects that aren’t gravitationally bound together does evolve with time.

That implies that energy is no longer conserved in an expanding Universe!

Enter Emmy Noether and her work on symmetry and conserved quantities - as described in the following link from which I have edited the above information. ;)

https://bigthink.com/starts-with-a-bang/expanding-universe-conserve-energy/
I have a very nice book that is a collection of articles written by imminent scientists. One of them is by Einstein with exactly the same drawing as above and he is explaining conservation of energy and how energy can take different forms and change from one kind to another. In the case above you have kinetic energy at the bottom of the pendulum swing that transfers to gravitational potential energy at the top. Kind of also leads onto the idea of resonance where you have two forms of energy storage at play. In a LC tank circuit for example you are storing energy as electric charge in the capacitor or as magnetic field energy in the inductor so as the energy bounces back and forth, you get damped oscillation (just add a dash of gain and you have sustained oscillation).
 
I always read your links, Galu.

But I think I will put conundrums about Energy Conservation in an expanding Universe on the back-burner for now.

https://math.ucr.edu/home//baez/physics/Relativity/GR/energy_gr.html

https://bigthink.com/starts-with-a-bang/expanding-universe-conserve-energy/

It will take 10 years postdoc research to get near it IMO. The Maths is fierce! Maybe it is the product of Energy and Time that is Conserved. Er, makes up a name: ET-Conservation? Oh wait, that is the definition of Action! I amaze myself sometimes. :cool:

I shudder to mention this, for fear of what our learned member and electric plasma man, @cumbb will say, but Amateur Scientists have discovered Plasma in Space near M31 Andromeda:

Plasma Arc.jpg


https://www.bbc.co.uk/news/in-pictures-66807814

Turns out Drechsler and his buddies are pretty competent Astronomers:

https://iopscience.iop.org/article/10.3847/2515-5172/acaf7e

I thought to myself, it can't be hard to figure out what the turquoise blob is made of:

Solar Spectrum 2.png

The Turquoise F-line is odds-on Hydrogen Beta, since most of space is filled with hydrogen AFAIK, and with all that talk of an Oiii filter being used, we can't rule out Doubly Ionised Oxygen.

Oiii filter.png

That photo seems to be some huge long exposure composite image. On a 106mm telescope. I am impressed! :)
 

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In an LC tank circuit...

That's a good electrical analogue of energy conservation in the gravitational field..

The charge momentarily at rest on the plates of the capacitor is equivalent to the mass of the pendulum bob momentarily at rest at the extreme of its oscillation. Energy stored in the electric field between the capacitor plates is therefore analogous to energy stored in the gravitational field. .

Wikipedia likens the to and fro movement of a pendulum to water sloshing back and forth in a tank - hence the term "LC tank circuit".

Perhaps we should now be revisiting the Oscillating Universe Theory?

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Just don't tell TNT! ;)
 
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You, too, must become more precise in looking and delimiting, differentiate and define. Otherwise, all that remains is mainstream populary noscience:
Universe cannot expand. Even according to mainstream Wikipedia it does not. "Parts" of "universe" "expanded", would "expand": "space" and "time": "space-time"-)
Step by step;-)
 
I'm going to switch to Unignore for a trial period.

I must learn to be tolerant of contributors who hold an opinion at odds with what is generally accepted! :whistle:
Remember Galileo. His view (turned out he was right) was completely at odds with what was generally accepted. He was in fact branded a heretic.

That said, I struggle with the ‘electric universe’

🙂
 
I have no difficulty at all with the "Electric Universe". I understood QED at a young age!

https://en.wikipedia.org/wiki/QED:_The_Strange_Theory_of_Light_and_Matter

I can usually wire up my electric gadgets to work. Unhappily, my old Rotel RT-950BX FM tuner collapsed today. I think it might be a corroded connection on the 300 ohm Aerial, but really, I don't know.

Investigations ongoing, but I have a temporary fix. I have a DAB 1 tuner also. DAB 2 might be preferable, but I can live with it.

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Found a suitable cable:

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Order happily restored on DAB. Back on BBC 5L!

https://www.bbc.co.uk/sounds/play/live:bbc_radio_five_live

They don't teach that in school! It's a gift! :D
 
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OIII filters make use of absorption / forbidden lines in it's spectrum. When a photo is taken this means that the image of spectrum captured is black. In practice significantly blacker than other light that slips through the filer or due to ccd noise etc. When actual photo's are produced the degree of blackness is converted to some colour. Lot's of astro photo's use the same technique. Filters and chosen colours to represent them.

The telescope used may well have cost £8k+ The larger one used to confirm, rather a lot more,