I recall John Gribbin, author of The Jupiter Effect, as an author of several popular science books. One I recall reading is "In Search of Schrodinger's Cat," one of several popular treatments of quantum mechanics I vaguely recall reading in my 20s. In retrospect I'm glad I didn't go to a college to get a physics degree, even back then things were much more complicated than presented in popular books. And if I had managed to get a degree, I might have spent a career chasing string theory.
I just looked to see what other books he's written, and I'm surprised at his voluminous output. One is a Feynman bio. I have a copy somewhere but I haven't read it, it's only maybe 1/3rd the thickness of James Gleick's Feynman bio, which I've only partly read.
Of his other books, most are sciencey, but there's a bio of Buddy Holly! I think Buddy's main scientific accomplishment was as an early popularizer of the Fender Stratocaster. There's 300 or so listings here, though one or two dozen appear to be articles he wrote in Analog SF, but still, this approaches an Asimov level of book writing!
https://www.goodreads.com/author/list/1418.John_Gribbin?page=1&per_page=30
I just looked to see what other books he's written, and I'm surprised at his voluminous output. One is a Feynman bio. I have a copy somewhere but I haven't read it, it's only maybe 1/3rd the thickness of James Gleick's Feynman bio, which I've only partly read.
Of his other books, most are sciencey, but there's a bio of Buddy Holly! I think Buddy's main scientific accomplishment was as an early popularizer of the Fender Stratocaster. There's 300 or so listings here, though one or two dozen appear to be articles he wrote in Analog SF, but still, this approaches an Asimov level of book writing!
https://www.goodreads.com/author/list/1418.John_Gribbin?page=1&per_page=30
Breathe easy for I have weathered storm Éowyn, even though wind speeds of 100 mph were recorded at the weather station just 10 miles away!
Thanks for satisfying my curiosity as to what Asimov had to say in his foreword to The Jupiter Effect:
Your illustration of the Earth as a black hole is interesting, but could the Earth actually become a black hole?
Only if the electromagnetic and quantum forces holding the Earth up against gravitational collapse were somehow turned off would the Earth become a black hole. Then, in a matter of minutes, the entire mass of the Earth would collapse into a black hole just 17 mm in diameter as per your illustration.
Karl Schwarzschild assured us that even the Sun could not become a black hole, but as a thought experiment the Schwarzschild radius would be about 3 kilometres.
John Wheeler probably wondered that as well!
This is the Maths and Physics section of my library, the rack on the immediate right:
Most of it is junk. But they do have Feynman's Lectures on Gravitation, which is a rather heavy Postgraduate QFT thing about Spin 2 Gravitons which Feynman never got to work.
But @benb, you've got me thinking... which one of these two serious tomes, in stock in the store at Portsmouth Central Library did I read about 20 years back?
I think it was the second. by Jagdish Mehra IIRC, it was quite brilliant and included some serious Physics, but perhaps not much on Gravitation. But I will check.
As mentioned before, this Feynman Lecture 42, from Vol. 2 of his Physics series is quite enlightening:
https://www.feynmanlectures.caltech.edu/II_42.html
There is more:
Soon I will be doing more calculations on Curved Space and its mysteries:
It's rather interesting to me that a Neutron Star accretes matter in such a way as to increase its rotation speed. Dr. Becky was banging on about this recently.
Most of it is junk. But they do have Feynman's Lectures on Gravitation, which is a rather heavy Postgraduate QFT thing about Spin 2 Gravitons which Feynman never got to work.
But @benb, you've got me thinking... which one of these two serious tomes, in stock in the store at Portsmouth Central Library did I read about 20 years back?
I think it was the second. by Jagdish Mehra IIRC, it was quite brilliant and included some serious Physics, but perhaps not much on Gravitation. But I will check.
As mentioned before, this Feynman Lecture 42, from Vol. 2 of his Physics series is quite enlightening:
https://www.feynmanlectures.caltech.edu/II_42.html
There is more:
Soon I will be doing more calculations on Curved Space and its mysteries:
It's rather interesting to me that a Neutron Star accretes matter in such a way as to increase its rotation speed. Dr. Becky was banging on about this recently.
But leaves us mere mortals gasping for an explanation!
What does Feynman mean by "our space is curved" and what is this "radius excess" of which he speaks?
As we all know, it is actually spacetime that is curved, but here Feynman looks at the particular case of the geometry inside a massive spherically symmetric object with uniform density in which he discusses the curvature of space.
When Feynman talks about a "predicted radius" he means the radius of the sphere in a Euclidean space.
However space inside the sphere is not Euclidean, it is slightly curved, so the distance to the center of the sphere is ever so slightly larger than you would expect.
The difference between the predicted radius and the above mentioned distance is called the "radius excess".
P.S. Note that these massive uniform density spheres are not to be confused with black holes.
I've looked a little into "Gravitational light deflection at a neutron star".
An accreting neutron star is a bright X-ray source, and X-ray pulses may be observed due to its rotation.
Since X ray photons cannot travel in straight lines in the intense gravitational filed, the observed pulses have complex profiles (see attached gif).
https://www.sternwarte.uni-erlangen.de/remeis-start/research/x-ray-astronomy/accreting-neutron-stars/#:~:text=Due to strong magnetic field of the neutron,until it settles on the neutron star surface.
An accreting neutron star is a bright X-ray source, and X-ray pulses may be observed due to its rotation.
Since X ray photons cannot travel in straight lines in the intense gravitational filed, the observed pulses have complex profiles (see attached gif).
https://www.sternwarte.uni-erlangen.de/remeis-start/research/x-ray-astronomy/accreting-neutron-stars/#:~:text=Due to strong magnetic field of the neutron,until it settles on the neutron star surface.
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Tonight, as the planets align in honour of Scotland's national bard, my family and I prepare for our own little Burns Supper.
A wild hagg (much more succulent than the farmed variety) will soon be on the boil, along with the necessary neeps and tatties.
A little known fact about Robert Burns that will resonate with this thread is that he was well educated in both astronomy and mensuration.
A wild hagg (much more succulent than the farmed variety) will soon be on the boil, along with the necessary neeps and tatties.
A little known fact about Robert Burns that will resonate with this thread is that he was well educated in both astronomy and mensuration.
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If it has serious technical content, then I'd have to guess that's the one you read. The best I remember about John Gribbin's writing is it tended to be more lightweight.
If I get the interest to read more about Feynman, I may have to get that book and read it myself. I've not heard of it before.
I seem to have got onto A RIDE into High Energy Physics here! 🤣
The delightful women at Portsmouth Library said they really enjoy hunting down old books in the dark cobwebby basement of the library. It is a challenge and breaks the routine.
TBH, I have probably read too many murder mysteries, but was worried if she would return. 🙁
Thus I have the Jagdish Mehra 530.0924 book in my mitts:
The Gleick book is proving elusive, but I think it was my fault in saying it was called Feynman, not Genius and we only had Dewey 530 which is all of Physics to go on:
Anyway, I am gripped. Feynman has just roomed with a bright young Postgrad, and presented the student's novel idea of Parity breaking to a learned conference on the basis the professors will listen to him.
https://en.wikipedia.org/wiki/Kaon
Talk of Pauli proposing the Neutrino to solve the weird spectrum of Beta Decay electron energy and spin deficit.
Currently reading Feynman's attempt to properly explain the Weak Interaction. I am wondering what he will come up with. W and Z bosons? Feynman diagrams? IDK yet.
Also I didn't know Feynman came up with the idea of Quarks, though he called them Partons.
All of it dressed up in proper mathematics with words like Axial Vectors, Unitary, Hermitian and so on. I don't know what those words mean, but I am sure it will all make sense.
There is that famous picture of him and taciturn Dirac having curt discussions by the tombstone too.
I am Dirac.
I am Feynman. What are you working on?
Mesons. And you?
QED.
Do you have an equation?
No.
One must try...
Always makes me giggle. 😛
The delightful women at Portsmouth Library said they really enjoy hunting down old books in the dark cobwebby basement of the library. It is a challenge and breaks the routine.
TBH, I have probably read too many murder mysteries, but was worried if she would return. 🙁
Thus I have the Jagdish Mehra 530.0924 book in my mitts:
The Gleick book is proving elusive, but I think it was my fault in saying it was called Feynman, not Genius and we only had Dewey 530 which is all of Physics to go on:
Anyway, I am gripped. Feynman has just roomed with a bright young Postgrad, and presented the student's novel idea of Parity breaking to a learned conference on the basis the professors will listen to him.
https://en.wikipedia.org/wiki/Kaon
Talk of Pauli proposing the Neutrino to solve the weird spectrum of Beta Decay electron energy and spin deficit.
Currently reading Feynman's attempt to properly explain the Weak Interaction. I am wondering what he will come up with. W and Z bosons? Feynman diagrams? IDK yet.
Also I didn't know Feynman came up with the idea of Quarks, though he called them Partons.
All of it dressed up in proper mathematics with words like Axial Vectors, Unitary, Hermitian and so on. I don't know what those words mean, but I am sure it will all make sense.
There is that famous picture of him and taciturn Dirac having curt discussions by the tombstone too.
I am Dirac.
I am Feynman. What are you working on?
Mesons. And you?
QED.
Do you have an equation?
No.
One must try...
Always makes me giggle. 😛
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Their meeting took place at the International Conference on Relativistic Theories of Gravitation in Warsaw in 1962.
A nearby physicist found the conversation so remarkable that he jotted it down:
F: I am Feynman.
D: I am Dirac.
(Silence)
F: It must be wonderful to be the discoverer of that equation.
D: That was a long time ago.
(Pause)
D: What are you working on?
F: Mesons.
D: Are you trying to discover an equation for them?
F: It is very hard.
D: One must try.
(From Genius by James Gleick, 1992 p. 228)
A nearby physicist found the conversation so remarkable that he jotted it down:
F: I am Feynman.
D: I am Dirac.
(Silence)
F: It must be wonderful to be the discoverer of that equation.
D: That was a long time ago.
(Pause)
D: What are you working on?
F: Mesons.
D: Are you trying to discover an equation for them?
F: It is very hard.
D: One must try.
(From Genius by James Gleick, 1992 p. 228)
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Any hadron (e.g. a proton) can be considered as being made up of partons.
We are familiar with quarks and gluons, which are collectively known as partons.
Quarks and gluons in a proton
When protons collide at high energy in the Large Hadron Collider (LHC), the result is a shower of partons.
The partons then form new particles, the energies of which can yield information about the strength of the strong nuclear force.
Feynman came up with the parton model in 1969 thus providing the wherewithal to analyse high energy hadron collisions.
Wikipedia goes into the detail: https://en.wikipedia.org/wiki/Parton_(particle_physics)
This following question has likely already been addressed somewhere within this rather lengthy thread, so I would appreciate it if someone could point out the post number for me.
My question is, if I understand it correctly, and I’m certain I don’t, according to Einstein, mass distorts space. The distortion of space accelerates mass, which we term, gravity. That explanation seems circular, and not providing a reason for why mass distorts space, and for why distorted space accelerates mass. What is there about mass that causes space to distort. In other words, the basic explanation is for what happens, not for WHY it happens. Is there an accepted explanation in physics?
My question is, if I understand it correctly, and I’m certain I don’t, according to Einstein, mass distorts space. The distortion of space accelerates mass, which we term, gravity. That explanation seems circular, and not providing a reason for why mass distorts space, and for why distorted space accelerates mass. What is there about mass that causes space to distort. In other words, the basic explanation is for what happens, not for WHY it happens. Is there an accepted explanation in physics?
The density and flux of energy and momentum are the sources of the gravitational field in general relativity, just as mass density is the the source of such a field in Newtonian gravity.
Consequently, not only matter (mass), but also radiation (e.g. light) distorts space.
Think about that - the fact that light also distorts space only makes it more difficult to explain why the distortion happens!
The best answer I can give right now is that Einstein's field equations do not care about cause and effect, but simply describe the phenomenon in a way that agrees with observations.
Although general relativity predicts that light will attract objects gravitationally, I believe this effect is far too weak to have yet been measured.
In our familiar three-dimensional space, we are used to talking about 'momentum', a vector in three dimensions.
However, in four-dimensional space we have to talk about 'energy-momentum 4-vector' or 'four-momentum'.
I have read that we may regard the 'four-momentum' of a particle as the gravitational analogue of electric charge.
Therefore, the way I like to think about it is this:
Just as the electric charge of a particle can produce an electric force, so can the four-momentum of a photon produce a gravitational force.
OK, I know that's simply an analogy!
In our familiar three-dimensional space, we are used to talking about 'momentum', a vector in three dimensions.
However, in four-dimensional space we have to talk about 'energy-momentum 4-vector' or 'four-momentum'.
I have read that we may regard the 'four-momentum' of a particle as the gravitational analogue of electric charge.
Therefore, the way I like to think about it is this:
Just as the electric charge of a particle can produce an electric force, so can the four-momentum of a photon produce a gravitational force.
OK, I know that's simply an analogy!
Just a gentle thought, @Galu, if you could construct your multiple posts into one concise one, we would have more chance of staying on the same 20 post page. You are currently scoring 8/14 on this page.
Soon "All this will be Lost.... like Tears in Rain..." 😢
I suffer from a mental disorder called "Confusion". And you are worsening it. I say this kindly.
@Ken Newton raises an interesting point. I went to the source, Mr. Einstein's tome: "Relativity. the Special and General Theory", which you can download by switching page view:
https://archive.org/details/relativitythespe00einsuoft/page/n3/mode/2up?view=theater
As we know, Special Relativity is based on the premise that the speed of light is the same for all observers. The stuff about time and the Lorentz Transform in a flat Minkowski Space follows almost inevitably.
Now think about it. If you lived in freefall in Space, say on the ISS, you would know nothing about Gravity really. Your bathroom scales wouldn't work, and you would have no easy way of weighing yourself!
Einstein did however have the happy notion that acceleration was locally indistinguishable from Gravity. He called this the equivalence principle. This led to the notion that Inertial Mass is the same as Gravitational Mass.
He also noted through thought experiments, that strange things were going on with the triangles and rectangles he constructed. They acted as though the Space was non-Euclidian or Curved.
https://en.wikipedia.org/wiki/Principle_of_relativity#General_relativity
Well it goes on. Feynman explains curved space or Spacetime quite well here:
https://www.feynmanlectures.caltech.edu/II_42.html
And how you might measure it. And it has been measured. Eclipses bending light, Clocks running slow in a gravitational field as well as a moving frame. Mercury precessing.
I can't explain why Mass-Energy bends Space, but it does. And Space tells Mass-Energy where to go. And the famous equations follow rather inevitably:
https://bigthink.com/starts-with-a-bang/einstein-general-theory-relativity-equation/
It is amazing that he worked this out from such simple principles. A Universe constructed any other way just wouldn't work right.
Soon "All this will be Lost.... like Tears in Rain..." 😢
I suffer from a mental disorder called "Confusion". And you are worsening it. I say this kindly.
@Ken Newton raises an interesting point. I went to the source, Mr. Einstein's tome: "Relativity. the Special and General Theory", which you can download by switching page view:
https://archive.org/details/relativitythespe00einsuoft/page/n3/mode/2up?view=theater
As we know, Special Relativity is based on the premise that the speed of light is the same for all observers. The stuff about time and the Lorentz Transform in a flat Minkowski Space follows almost inevitably.
Now think about it. If you lived in freefall in Space, say on the ISS, you would know nothing about Gravity really. Your bathroom scales wouldn't work, and you would have no easy way of weighing yourself!
Einstein did however have the happy notion that acceleration was locally indistinguishable from Gravity. He called this the equivalence principle. This led to the notion that Inertial Mass is the same as Gravitational Mass.
He also noted through thought experiments, that strange things were going on with the triangles and rectangles he constructed. They acted as though the Space was non-Euclidian or Curved.
https://en.wikipedia.org/wiki/Principle_of_relativity#General_relativity
Well it goes on. Feynman explains curved space or Spacetime quite well here:
https://www.feynmanlectures.caltech.edu/II_42.html
And how you might measure it. And it has been measured. Eclipses bending light, Clocks running slow in a gravitational field as well as a moving frame. Mercury precessing.
I can't explain why Mass-Energy bends Space, but it does. And Space tells Mass-Energy where to go. And the famous equations follow rather inevitably:
https://bigthink.com/starts-with-a-bang/einstein-general-theory-relativity-equation/
It is amazing that he worked this out from such simple principles. A Universe constructed any other way just wouldn't work right.
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So your library keeps all the books that have ever been available? Just about all the libraries I've been to get rid of "unpopular" books through book sale events and such, but these are usually "branch" locations. I've only been to the main Atlanta library once, I recall it was two or three floors, back when I was in college. I don't even remember where it is.
I see copies online under $10, and am tempted to get one. Just checked my local library system (Dekalb, does not include Atlanta) which of course doesn't have it. I'm surprised when they DO have a book I want.
I recall earlier in the thread posting something where I assumed light had a gravitational force (due to the equivalence of mass and energy), but another poster said it definitely did not. Of course having a force "too low to measure" is not the same as not having a force.
I'm wondering what the force would be from one of the more high-energy light sources available on Earth, such as a laser of several megawatts. If modulated, it could cause resonant movement in a nearby high-Q device tuned to the same frequency (pendulum or tuning fork), with which even a microscopic displacement could be measured. Of course, before doing the experiment one would calculate the theoretical force generated to see if it would result in a measurable displacement, but I don't know how to do that offhand.
This resonant mass would of course be shielded from the actual laser, as light is known to put a slight pressure on an object it shines on. Light sails have been tested in low Earth orbit.
Here's a laser that puts out over 20 kilowatts and is modulated at 50kHz. This is an (ahem) "ordinary industrial laser" - no doubt there are military lasers many times its power:
It is the nature of IP addresses that THEY know exactly where you live. Thus I don't understand why many of you are so stealthy with personal details. It's no good being paranoid,,they will get you anyway!
I am surprised that Science books are even allowed in the deep south of Atlanta. This is the land of church-going and book-banning, IIRC. Where surely it is all explained in "The Good Book"? 🙄
In the UK, for a small fee, the library service will get hold of anything you want, even if it is the British Library copy. But I think I can turn up the Gleick book with little effort. But you can tell me what you think of it as a serious Physics tome.
Anywhoo, with now onlythree two posts before we turn the page I had better hurry up.
My perusal of the Mehra book last night in 'Spoons was interrupted by urgent discussions of some true statement about a friend's personal finances I made in front of one of the Pub's sexbombs. I later realised I had scuppered my friend's romantic aspirations, which is why he is upset! We then moved onto Bitcoins, and frankly nobody knows what they are or why we should want them. Schemes to make a $1000 of money with a million Youtube followers and becoming "an influencer" or something were similarly confusing. I really don't understand the modern world. Or why we should care. 🤣
I am sure that Photon energy must be included in graviational calculations. But the effect is very small indeed.
The deflection of the tails of Comets are more an electromagnetic effect:
As ever, Einstein's Relativistic treatment of Mass-Energy applies even to massless Photons:
The Photon linear momentum has a simple form:
When a reddish 2.46 eV photon, say from a Laser, hits a small electron head on, it imparts a mere 1460 m/s velocity in a rough calculation:
Which must resemble Compton Scattering. And might be applicable to light sails in spacecraft, But this is nothing to do with gravity.
I am surprised that Science books are even allowed in the deep south of Atlanta. This is the land of church-going and book-banning, IIRC. Where surely it is all explained in "The Good Book"? 🙄
In the UK, for a small fee, the library service will get hold of anything you want, even if it is the British Library copy. But I think I can turn up the Gleick book with little effort. But you can tell me what you think of it as a serious Physics tome.
Anywhoo, with now only
My perusal of the Mehra book last night in 'Spoons was interrupted by urgent discussions of some true statement about a friend's personal finances I made in front of one of the Pub's sexbombs. I later realised I had scuppered my friend's romantic aspirations, which is why he is upset! We then moved onto Bitcoins, and frankly nobody knows what they are or why we should want them. Schemes to make a $1000 of money with a million Youtube followers and becoming "an influencer" or something were similarly confusing. I really don't understand the modern world. Or why we should care. 🤣
I am sure that Photon energy must be included in graviational calculations. But the effect is very small indeed.
The deflection of the tails of Comets are more an electromagnetic effect:
As ever, Einstein's Relativistic treatment of Mass-Energy applies even to massless Photons:
The Photon linear momentum has a simple form:
When a reddish 2.46 eV photon, say from a Laser, hits a small electron head on, it imparts a mere 1460 m/s velocity in a rough calculation:
Which must resemble Compton Scattering. And might be applicable to light sails in spacecraft, But this is nothing to do with gravity.
I found this paper on "Gravitational properties of light - the gravitational field of a laser pulse":
https://iopscience.iop.org/article/10.1088/1367-2630/18/2/023009
Quote: "Nearby test particles at rest are attracted towards the pulse trajectory by the gravitational field due to the emission of the pulse, and they are repelled from the pulse trajectory by the gravitational field due to its absorption."
Crucially, this paper describes a mathematical model and, as the conclusion states, "the experimental detection of the gravitational effect of a laser pulse is way out of reach".