What is the Universe expanding into..

[Galu]

Any resemblance to the Cheshire Cat is purely coincidental!

 

[Galu]

That brings us back to physics!

"The Cheshire Cat" is a phenomenon in quantum mechanics in which a particle and its property behave as if they are separated, or when a particle separates from one of its physical properties. To test this idea, researchers used an interferometer where neutron beams passed through silicon crystal. The crystal physically separated the neutrons and allowed them to go to two paths. Researchers reported "the system behaves as if the neutrons go through one beam path, while their magnetic moment travels along the other."

Cheshire Cat - Wikipedia

 

[system7]

I would like to know more about that Neutron thingie. Neutrons are very pure things, being uncharged. But IIRC, still have a magnetic moment. Which needs explaining.

But you really must get away from planetary models of the subatomic world.

That is SO wrong.

This is better for Positronium IMO. Bears some resemblance to 2p orbitals in the Hydrogen Atom.

Positronium is interesting because it is free of baryonic influence, ie Neutrons, Protons and all the other Bosonic clutter that comes with them. A very pure electromagnetic system ideal to test QED.

Incidentally, Cosmology for the Curious is still a freebie!

Cosmology for the Curious | SpringerLink

 

[esgigt]

But you really must get away from planetary models of the subatomic world.

I agree.... the planetary models fail in every aspect.

 

[Galu]

Models change as new scientific discoveries are made. However, each model is relevant in terms of the particular scientific phenomenon being examined at the time of its introduction.

For example, Thomson's Plum Pudding Model was adequate to explain charging by friction, but to explain the existence of spectral lines required the introduction of the Bohr Planetary Model.

Models become more sophisticated as we try to explain our new discoveries in science, but no model fails in the context within which it was originally introduced.

When it comes to the subatomic world, I'm afraid the models become purely mathematical. That's problematical for a simple soul like me who would prefer a picture!

 

[system7]

I was always curious why what is called Modern Art is actually about 100 years old.

Same can go for most of what is taught in Schools:

Having established that Positronium lasts a very short time:

t = 2 hbar / mc^2 a^5 = 0.1244ns !

Maybe we can figure out why the Neutron lasts about 15 minutes in the wild.

Can't be hard, can it?

 

[Bonsai]

“Incidentally, Cosmology for the Curious is still a freebie!”

I’ve downloaded it. Looks good.

 

[system7]

Bonsai, enjoy!

24.3 Answers to the “Big Questions”

We opened this book asking a few basic questions: Is the universe finite
or infinite? Has it existed forever? If not, when and how did it come into
being? Will it ever end?

Philosophers and theologians have been arguing
about these questions for millennia, and one might expect that all possible
answers have already been anticipated.

However, the worldview suggested
by modern Cosmology is not what anyone expected....

No spoilers from me. It's all breaking news IMO.

 

[Galu]

Maybe we can figure out why the neutron lasts about 15 minutes in the wild.

Apparently, neutrinos are responsible for the decay of free neutrons.

The attached model of the neutron shows an additional electron at the centre of the structure. When a neutrino collides with the electron in the neutron’s center, it dislodges it.

The reason that a neutron lasts for "15 minutes in the wild" is that there is a probability of a solar neutrino hitting it every 15 minutes. The neutron becomes a proton in the process, known as Beta Minus Decay.

 

[dreamth]

Would it be possible that the whole universe be made out of one single particle that is moving so fast that we all are just its time instances?

 

[Galu]

I don't know, dreamth. Maybe Walt Whitman has the answer!

When I heard the learn’d astronomer;
When the proofs, the figures, were ranged in columns before me;
When I was shown the charts and the diagrams, to add, divide, and measure them;
When I, sitting, heard the astronomer, where he lectured with much applause in the lecture-room,
How soon, unaccountable, I became tired and sick;
Till rising and gliding out, I wander’d off by myself,
In the mystical moist night-air, and from time to time,
Look’d up in perfect silence at the stars.
– Walt Whitman

 

[Galu]

The SpaceX crew has returned safely to Earth.

Splashdown in the Gulf of Mexico was at 19.48pm BST.

Those blossoming parachutes were a wonderful sight!

The fast recovery boats are now approaching the Dragon as I type.

 

[dreamth]

"Are we Seeing Signals from Before the Big Bang?" - Professor Sir Roger Penrose OM FRS - YouTube

 

[Galu]

I'll watch that when I've got a spare 90 minutes!

Last person to deliver me a lecture was my wife!

 

[TNT]

56 minutes in... really ... a collision of BH "reaches" into the next enigma .... I wasn't convinced...

But the talk up to here didn't break my comforting idea of the whole gig... I need to sleep. Maybe I'll finish it later. Good show - thanks!!

//

 

[system7]

Glad that Bob and Doug got back safely after 2 months circling our little blue planet:

Nasa SpaceX crew return: Dragon capsule splashes down - BBC News

I wonder how they passed the time on the International Space Station?

Probably not trying to figure out why Neutrons last 15 minutes, as I have:

I am making progress. Particle decay - Wikipedia

But it's taking me into deep waters: Four-momentum - Wikipedia

I think I followed old Penrose though. All ripples on a sort of pond.

 

[dreamth]

56 minutes in... really ... a collision of BH "reaches" into the next enigma .... I wasn't convinced...

But the talk up to here didn't break my comforting idea of the whole gig... I need to sleep. Maybe I'll finish it later. Good show - thanks!!

//

This next guy got alredy two grants of 1 million dollars for studying black holes in France while he's also an orthodox priest which might actually talk about the utility of all this type of science...In the last decade or so our Romanian government (the physics guy is aso romanian...)just payed the Romanian Orthodox Church about a billion dollars while the minimum wage is about 300 dolars/month...priests are payed from the taxpayers's money here... I think there are a lot of scientists who should simply be sent in Africa to plant trees for the money they get on stupid useless research...

Iosif Bena - What do black hole microstates look like? - YouTube
Un preot roman cu studii la MIT propune schimbarea teoriei lui Einstein

 

[Bonsai]

This is an excellent introduction. DrPhysicsA steps through the whole equation discussing each part in depth incl. the Tensor matrices and Ricci curvature. About 2 hours, but you come out with even greater respect for Einstein.

Einstein Field Equations - for beginners! - YouTube

I do wish those that cry ‘Einstein was wrong’ would take the time out to do a bit of reading . . .

(BTW DrPhysicsA’s other videos are also excellent)

 

[system7]

I've burned a lot of data bandwidth on my phone this month so long Videos are out for now.

Einstein's General Relativity is 10 independent components in a 4D Space IIRC. I think you can do this sort of thing with big matrices, but way beyond my ability. Ricci flat is always the key idea.

It's OK to enjoy some of the mysteries of 4D, and rotation or spin is certainly one of them:

I have been digging around on the Neutron lifetime:

For over a decade, physicists have puzzled over the neutron lifetime: how long, on average, it takes the isolated particle to decay into a proton, electron, and antineutrino. Counting the number of neutrons in a container over time, they measure the half-life to be about 14 minutes and 39 seconds. Using a different experimental method where they count one of the neutron’s decay products, they measure the lifetime to be about 8 seconds longer.

Evidently an important thing. Determines the ratios of elements in the Universe and may even get a handle on Dark Matter. But no simple maths involved: Flavor changing Neutrinos and Quarks and 1/3 charge and three generations of matter takes some explaining.

Quanta Magazine

F.E. Wietfeldt has a mathematical paper way over my head: "Measurements of the Neutron Lifetime"

Simpler way of looking at it might be Fermi's Golden Rule.

I was hoping it would just be the Uncertainty principle between Energy and Time with a fudge factor thrown in. But no. I think I may leave that problem to the Professionals.

How did Cosmology for the Curious work for you, Bonsai? We apparently exist between the Big Bang and the subsequent Big Crunch. With a sea of negative Energy playing a mysterious part.

 

[Galu]

I have been digging around on the Neutron lifetime. Evidently an important thing. Determines the ratios of elements in the Universe. Quanta Magazine

That's interesting! According to your link, knowing the neutron’s lifetime allows the calculation of the relative abundances of hydrogen and helium that would have been produced during the universe’s first few minutes.

The faster that neutrons decayed into protons during that time, the fewer that would have been left over for the production of helium. The balance of hydrogen and helium is apparently a very sensitive test of the dynamics of the Big Bang theory.