But no kinetic energy. I assume because they travel at the speed of light as soon as emitted. Their energy is proportional to frequency. Particles with wave like properties. Some devices such as lasers, masers, 1/2 and 1/4 wave stubs are wave like devices. A device used to be used to measure microwaves. A probe moved along a waveguide. It could measure both voltage and current waveforms. 😉 Sine waves. Maybe there is a particle theory now. Pass perhaps particle spacing and associated fields.
We hear about Maxwell. A bit from britanica
Why did it take 25 more years for Maxwell’s theory to be accepted? For one, there was little direct proof of the new theory. Furthermore, Maxwell not only had adopted a complicated formalism but also explained its various aspects by unusual mechanical concepts. Even though he stated that all such phrases are to be considered as illustrative and not as explanatory,
The ideas of Faraday and Maxwell that the field of force has a physical existence in space independent of material media were too new to be accepted without direct proof.
The impasse was finally removed by Hertz’s work. In 1884 Hertz derived Maxwell’s theory by a new method and put its fundamental equations into their present-day form.
Four years later, Hertz made a second major contribution: he succeeded in generating electromagnetic radiation of radio and microwave frequencies, measuring their speed by a standing-wave method and proving that these waves have the properties of reflection, diffraction, refraction, and interference common to light. He showed that such electromagnetic waves can be polarized, that the electric and magnetic fields oscillate in directions that are mutually perpendicular and transverse to the direction of motion, and that their velocity is the same as the speed of light, as predicted by Maxwell’s theory.
https://www.britannica.com/science/...on/Relation-between-electricity-and-magnetism
Faraday's thoughts 1831. The aether has cropped up a number of times over rather a lot of years. One interpretation.
https://en.wikipedia.org/wiki/Luminiferous_aether#Lorentz_aether_theory
Two people seem to be involved in use of the modern term even though it didn't fit with aspects that could be demonstrated
https://en.wikipedia.org/wiki/Luminiferous_aether#The_history_of_light_and_aether
Since photons have no inertial mass they can offer no resistance to being accelerated or decelerated, so always travel at speed c in a vacuum.
Light has energy and momentum which couples to gravity. Apparently the energy-momentum 4-vector of a particle, rather than its mass, is the gravitational analogue of electric charge, while the energy-momentum stress tensor which appears in Einstein's field equations is the corresponding analogue of electric current. I guess I would require a much greater understanding of both general relativity and electromagnetism to understand that!
The energy and momentum of light also generates curvature of spacetime. Therefore, general relativity predicts that light will attract objects gravitationally. I believe this effect is far too weak to have yet been measured.
Latest news on gravity:
A 15 year study of variations in the timings of signals from a 68 strong array of millisecond pulsars has revealed that spacetime is being stretched and compressed by gravitational waves which have wavelengths that are enormous compared to the ones that have been previously detected by LIGO.
https://nanograv.org/news/15yrRelease
To put that into perspective, LIGO wavelengths are thousands of miles in length while the new gravitational waves detected by NANOGrav have wavelengths of trillions of miles - a distance similar to the distance between the Sun and Proxima Centauri, i.e., 20 light-years in length.
These newly detected waves could originate from supermassive black hole binary systems which have been theorised for decades, but which scientists don't yet know exist.
A 15 year study of variations in the timings of signals from a 68 strong array of millisecond pulsars has revealed that spacetime is being stretched and compressed by gravitational waves which have wavelengths that are enormous compared to the ones that have been previously detected by LIGO.
https://nanograv.org/news/15yrRelease
To put that into perspective, LIGO wavelengths are thousands of miles in length while the new gravitational waves detected by NANOGrav have wavelengths of trillions of miles - a distance similar to the distance between the Sun and Proxima Centauri, i.e., 20 light-years in length.
These newly detected waves could originate from supermassive black hole binary systems which have been theorised for decades, but which scientists don't yet know exist.
Last edited:
There's something involving supermassive black holes merging (or not) called the "final parsec problem" that I hadn't heard of until seeing this video.
I'd heard of LISA (like LIGO but in solar orbit, covered in Space Interferometers in the diagram) maybe 10-15 years ago as LIGO was being built and such, but the LISA project didn't get funded (or lost funding) back then. It's apparently (if I haven't misunderstood) got funding now and may be operational in a decade or so.
I'd heard of LISA (like LIGO but in solar orbit, covered in Space Interferometers in the diagram) maybe 10-15 years ago as LIGO was being built and such, but the LISA project didn't get funded (or lost funding) back then. It's apparently (if I haven't misunderstood) got funding now and may be operational in a decade or so.
According to NANOgrav, scientists were concerned that supermassive black holes in binaries would not orbit each other close enough to generate the enormously long wavelength gravitational waves that have now been detected.
I read that this concern was expressed as the final parsec problem which suggests that the two orbiting supermassive black holes will stop getting closer to each other at a distance of around one parsec (3.2 light years).
It's got something to do with events going into ultra slow motion as the supermassive black holes exchange energy, resulting in time stretching out towards infinity. I guess this is now in doubt!
Perhaps your video will make it all clear, so I'll give it a whirl!
Last edited:
Towards the end of the video, the pulsar timing array employed by NANOgrav is mentioned.
I think I understood Dr. Becky's explanation of the final parsec problem, but would need a repeat viewing (or three!) to be sure!
I think I understood Dr. Becky's explanation of the final parsec problem, but would need a repeat viewing (or three!) to be sure!
Yeah, I took it as the supermassive black holes clearing out all the mass within light years (or maybe sucking in some of it so it disappears into the supermassive black holes themselves) so that they end up being two masses orbiting themselves at some distance, like a big flywheel with no friction and nothing around that just keeps on going for (almost) forever.
I always think ADHD when I watch the esteemed Doctor Becky Smethurst. Maybe just me.
I really don't know why people are so obsessed with Black Holes. They do what they do. And seen one, you seen em' all, IMO.
I suspect somebody has just done the maths wrong, as usual. Gravity is weird, because the gravitational fields or waves create more gravity.
I was watching the live Subaru telescope feed from Hawaii of the Perseid Meteors this morning, since our own UK skies were hopeless as usual.
That one took about 15 seconds to cross the sky. I think green ones are copper or nickel.
I really don't know why people are so obsessed with Black Holes. They do what they do. And seen one, you seen em' all, IMO.
I suspect somebody has just done the maths wrong, as usual. Gravity is weird, because the gravitational fields or waves create more gravity.
I was watching the live Subaru telescope feed from Hawaii of the Perseid Meteors this morning, since our own UK skies were hopeless as usual.
That one took about 15 seconds to cross the sky. I think green ones are copper or nickel.
Yes, not quite perpetual motion, but a motion which is stable over a timescale which approaches infinity.
However, there now seems to be a typical disagreement between the experimenters and the mathematicians.
The former say they have evidence that supermassive black holes can orbit each other closer than the limit that the latter have set.
However, other than the imminent mergers of supermassive black holes, there may be other sources of the enormously long wavelength gravitational waves, and which may point us towards new physics.
One such source is fuzzy cold dark matter, a new model for cosmological dark matter that has recently drawn the attention of cosmologists.
https://www.ncl.ac.uk/press/articles/latest/2023/06/fuzzydarkmatter/
Attachments
It's called "searching for the unknown" which is, indeed, a human obsession!
Coincidently, Black Holes: Searching for the Unknown is the title of Monday's new episode of The Sky At Night on BBC4.
I'll be watching it because Dr. Becky's on it! 😍
https://www.bbc.co.uk/programmes/m001pntf
Blackhole is a one way journey. Just like death. I think thats facinating enough. To fuel the obsession.
I keep sayin' this, Black Holes are the least of our problems. Though I am working on them. The Momentum-Energy 4-Vector seems promising.
https://hepweb.ucsd.edu/ph110b/110b_notes/node54.html
Many great Mathematicians have lived. Euclid, Pythagoras, Fr. Pierre de Fermat, Leonard Euler, Karl Friedrich Gauss, Sophie Germain, Felix Klein, David Hilbert, Emmy Noether, Srinivasa Ramanujan, John Conway...
But greatest of them all, IMO, was Emmy Noether.
https://en.wikipedia.org/wiki/Emmy_Noether
One can only wonder what she and young Albert Einstein discussed late into the night... though obviously a close working relationship.
As she had with another clever but older Mathematician, David Hilbert:
Honestly, the whole matter of Mathematics and Physics is like some sort of scandalous soap-opera, IMO. One day the truth will come out!
The Femme-Fatale of Science!
I myself am drawn to her mathematically appealing ideas of symmetry:
Though I have advanced into ideas of broken symmetry these days, and she too could let her hair down sometimes.
See the left shoelace is done right, the right shoelace will come undone.
https://bigthink.com/starts-with-a-bang/math-tie-shoes-correct/
Hope that makes sense.
https://hepweb.ucsd.edu/ph110b/110b_notes/node54.html
Many great Mathematicians have lived. Euclid, Pythagoras, Fr. Pierre de Fermat, Leonard Euler, Karl Friedrich Gauss, Sophie Germain, Felix Klein, David Hilbert, Emmy Noether, Srinivasa Ramanujan, John Conway...
But greatest of them all, IMO, was Emmy Noether.
https://en.wikipedia.org/wiki/Emmy_Noether
One can only wonder what she and young Albert Einstein discussed late into the night... though obviously a close working relationship.
As she had with another clever but older Mathematician, David Hilbert:
Honestly, the whole matter of Mathematics and Physics is like some sort of scandalous soap-opera, IMO. One day the truth will come out!
The Femme-Fatale of Science!
I myself am drawn to her mathematically appealing ideas of symmetry:
Though I have advanced into ideas of broken symmetry these days, and she too could let her hair down sometimes.
See the left shoelace is done right, the right shoelace will come undone.
https://bigthink.com/starts-with-a-bang/math-tie-shoes-correct/
Hope that makes sense.
Last edited:
Attachments
Because here also some scientists and science-interested people read along:
gravitational-physics does not explain it, but electro-physics does;-)
gravitational-physics does not explain it, but electro-physics does;-)
Puhlease @cumbb, no more Electric Universe crank science! It is just a waste of time.
Not strictly about Gravity, but I found this Perseid meteor image interesting:
The Perseids are in the trail of Comet Swift-Tuttle, which I remember seeing in 1992. Don't panic, but it could hit us apparently.
Anyway, my guess was wrong. Looks like a Magnesium meteor:
The red ones are more atmospheric artefacts. It doesn't work like the flame tests you might remember from the Chemistry Lab.
Not strictly about Gravity, but I found this Perseid meteor image interesting:
The Perseids are in the trail of Comet Swift-Tuttle, which I remember seeing in 1992. Don't panic, but it could hit us apparently.
Anyway, my guess was wrong. Looks like a Magnesium meteor:
The red ones are more atmospheric artefacts. It doesn't work like the flame tests you might remember from the Chemistry Lab.
Probably - she seems quite well grounded I think... Happy and enthusiastic - dont think there is a syndrome for that (yet) 😎
//
I enjoyed Dr. Becky's all too brief appearance on Monday's The Sky at Night programme.
Unsurprisingly, given that this is a programme aimed at an amateur audience, this black hole enthusiast learned nothing new.
LIGO got due attention, but the NANOgrav results were obviously too recent to be mentioned other than in passing.
Unsurprisingly, given that this is a programme aimed at an amateur audience, this black hole enthusiast learned nothing new.
LIGO got due attention, but the NANOgrav results were obviously too recent to be mentioned other than in passing.
The wave length of these gravity waves is amazingly large.
Does the frequency f = c / lambda makes sense.
Or the period T = lambda/ c
Do they relate to something as large or as long in the universe ?
Does the frequency f = c / lambda makes sense.
Or the period T = lambda/ c
Do they relate to something as large or as long in the universe ?
Gravitational waves travel at the speed of light in a vacuum, c, and they obey the wave equation, c = fλ.
The gravitational waves discovered by NANOgrav have frequencies in the order of nanohertz, which correspond to periods of months to decades.
The NANOgrav waves are thought to originate from supermassive black hole binary systems and can be 20 light-years in length.
The largest object in the Universe is thought to be a supercluster of galaxies called the Hercules-Corona Borealis Great Wall which is 10 billion light-years across! https://simple.wikipedia.org/wiki/Hercules–Corona_Borealis_Great_Wall