Betelgeuse has been getting increasingly bright and is now 142% of its usual luminosity, resulting in it being promoted from the 10th brightest star in the sky to the 7th.
Although previously expected to go supernova in the next few hundred thousand years, some scientists now predict that the star might explode much sooner than we thought.
If it happens in our lifetime it will be a spectacular sight, being visible by day as well as by night.
I looked at that with interest.
Mary Blagg discovered an improved formula for the Titius-Bode Law of Planetary Distances that I mentioned back in posts #820 and #822.
Blagg's formula takes into account the logarithm of the distances between the planets and satellites in the outer solar system and indicates that the solar system is best represented, not by a progression in '2' as per Bode's law, but by a progression in '1.7275'.
Blagg's work has stood the test of time, and astronomers have been using her formula for over a century to study the distances between planets and moons in our solar system and beyond.
https://acearchive.org/titiusbode-law
I don't thing "Bode's Law" of Planetary distribution is the sort of thing a serious scientist should spend time on. Mere mystic Numerology of the worst kind!
During the evolution of the solar system, planets have wandered all over the place orbitwise, according to computer simulations. The 4 gas giants have even entirely swapped places since the start of the solar system! Look it up.
Puzzle: Derive the Quantum Theory from the Light Radiation curve of ideal Black Bodies, or not far off the curve from our Sun at 5000 K, as Max Planck did in 1900!
https://en.wikipedia.org/wiki/Planck's_law
Looks a bit like an electrical impulse response to me, but IDK.
Here's the answer:
He must have seen that function somewhere before, IMO. Because it beats me! 😀
During the evolution of the solar system, planets have wandered all over the place orbitwise, according to computer simulations. The 4 gas giants have even entirely swapped places since the start of the solar system! Look it up.
Puzzle: Derive the Quantum Theory from the Light Radiation curve of ideal Black Bodies, or not far off the curve from our Sun at 5000 K, as Max Planck did in 1900!
https://en.wikipedia.org/wiki/Planck's_law
Looks a bit like an electrical impulse response to me, but IDK.
Here's the answer:
He must have seen that function somewhere before, IMO. Because it beats me! 😀
Yes, through a unique case with few points there are as many laws as one likes, that fit.
The theoretical models at the beginning of the 20th century all overestimated the amount of short-wavelength light emitted at a given temperature from a hot body.
In fact, the Raleigh-Jeans law predicted that an infinite amount of energy should be radiated away at shorter wavlengths!
This was obviously not right and was known as the Ultraviolet catastrophe, because it is not how hot things behave.
Planck, in an act of desperation, decided that light can only be emitted in packets , or quanta, whose energy is related to the wavelength of the light.
With the assumption that shorter wavelengths of light carry more energy and will be harder to radiate, he was able to avoid the Ultraviolet catastrophe.
It is interesting to note that Planck thought that this was a neat mathematical trick, and it fell to Einstein to take Planck's prediction seriously as a fundamental discovery about nature.
I acknowledge the writings of Prof. Brian Cox from which I've simplified the story of Planck's contribution to the quantum.
It is certainly worth reading about Mary Adela Blagg, FRAS (1858–1944), because her important work in astronomy deserves to be better known.
At the beginning of the 20th century, lunar features were known by several different names, so she produced a standardised list of lunar formations for use by selenographers, which was published in 1913 and extended in 1935.
It was also in 1913 that she came up with Blagg's Formula which was an improved form of Bode's law, and which I described above.
Another field to which Mary turned her attention was the analysis of the light curves of variable stars, hoping it might reveal their internal composition, which was a goal of the emerging science of astrophysics. She was a pioneer in applying mathematics to the light curves, which allowed her to characterise how the brightness changed with time.
Her international recognition and plaudits led to her rubbing shoulders with such greats as Arthur Eddington and Ejnar Hertzsprung, he of the star plot diagram fame.
You can find her full story here: https://academic.oup.com/astrogeo/article/57/5/5.17/2738839
And fittingly, after her death, she had a lunar crater named after her!
At the beginning of the 20th century, lunar features were known by several different names, so she produced a standardised list of lunar formations for use by selenographers, which was published in 1913 and extended in 1935.
It was also in 1913 that she came up with Blagg's Formula which was an improved form of Bode's law, and which I described above.
Another field to which Mary turned her attention was the analysis of the light curves of variable stars, hoping it might reveal their internal composition, which was a goal of the emerging science of astrophysics. She was a pioneer in applying mathematics to the light curves, which allowed her to characterise how the brightness changed with time.
Her international recognition and plaudits led to her rubbing shoulders with such greats as Arthur Eddington and Ejnar Hertzsprung, he of the star plot diagram fame.
You can find her full story here: https://academic.oup.com/astrogeo/article/57/5/5.17/2738839
And fittingly, after her death, she had a lunar crater named after her!
The interesting aspect is that it suggests there are mechanisms behind it that produce the results. Not that we will ever know what those mechanisms are.
Similar, using difference tables on data to see if an equation can fit it.
Also Planck's constant. It's empirical. It wasn't derived, It made his equation fit.
Another gravity related one, energy needs to figure some where as well.
https://en.wikipedia.org/wiki/Hubble_sequence
TBH I feel that the reasons for it being incorrect are rather stupid as circular. Just turn the sequence round and ignore where it is correct. Would Hubble have based his idea on galaxies that he couldn't really determine the shape of? He might infer from from features where he could see that.
These need an explanation too
https://en.wikipedia.org/wiki/Irregular_galaxy
😉 That one is fairly short.
https://en.wikipedia.org/wiki/Hubble_sequence
TBH I feel that the reasons for it being incorrect are rather stupid as circular. Just turn the sequence round and ignore where it is correct. Would Hubble have based his idea on galaxies that he couldn't really determine the shape of? He might infer from from features where he could see that.
These need an explanation too
https://en.wikipedia.org/wiki/Irregular_galaxy
😉 That one is fairly short.
Without overstating my case as a reasonably competent (Lower Second BSc(Lon)) Physicist, could I draw your attention to a great mystery of Physics?
https://johncarlosbaez.wordpress.com/2021/02/04/the-hoyle-state/
In a picture format:
We are in the business of doing serious Physics, and even spin 0 states are considered lucky:
Notice how Beryllium 8 does not naturally occur.
https://johncarlosbaez.wordpress.com/2021/02/04/the-hoyle-state/
In a picture format:
We are in the business of doing serious Physics, and even spin 0 states are considered lucky:
Notice how Beryllium 8 does not naturally occur.
Hubble - related to human nature sort of who did what. 1st part of book. Page 1 starts about 1/2 way through
https://download.e-bookshelf.de/download/0003/9268/55/L-G-0003926855-0013270325.pdf
https://download.e-bookshelf.de/download/0003/9268/55/L-G-0003926855-0013270325.pdf
Yes, galaxies come in four different shapes; spiral, elliptical, lenticular, and irregular.
My understanding of galaxy formation is that the huge elliptical galaxies have formed over the eons through a series of collisions involving smaller spiral galaxies. Interested parties should look here: https://en.wikipedia.org/wiki/Galaxy_formation_and_evolution
This caltech article looks at the motion of stars in a spiral galaxy: https://ned.ipac.caltech.edu/level5/Sept14/Kormendy/Kormendy4.html
Apparently, the general orbit of a star in a spiral galaxy is an unclosed rosette because the galaxy mass is distributed in radius and not all in one central point as, for example, in the Solar System.
Bewildered? Me too, but here's the accompanying diagram to make it all clear: 😉
The rotation is clockwise, a spiral arm is shown in red and the individual stars drift clockwise and counterclockwise in the corotation loop.
Such analyses are obviously designed to drive me loopy!
The salient point in your link with respect to this thread is:
"The astrophysicist Fred Hoyle predicted [the existence of the Hoyle State] based on stellar evolution. Without a state of this sort, it’s unlikely that carbon would be formed when alpha particles smack into beryllium nuclei in a star! And that would be a serious roadblock to the formation of carbon."
Back to the title of this thread.
Don't we have the answer to "what generates gravity" ?
The Higgs boson generates mass to all particles.
Mass generates gravity.
Don't we have the answer to "what generates gravity" ?
The Higgs boson generates mass to all particles.
Mass generates gravity.
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Mach's principle, in cosmology, hypothesis that the inertial forces experienced by a body in nonuniform motion are determined by the quantity and distribution of matter in the universe. It was so called by Albert Einstein after the 19th-century Austrian physicist and philosopher Ernst Mach.
What about photons? They are massless particles that don't interact with the Higgs field.
I read that, although inspired by Mach's principle, Einstein conceded that others were satisfied to proceed without reference to it in general relativity.
https://en.wikipedia.org/wiki/Mach's_principle
The density and flux of energy and momentum are the sources of the gravitational field in the Einstein field equations of general relativity.
https://en.wikipedia.org/wiki/Stress–energy_tensor
Although photons have no mass, they do possess energy and momentum.