I’ve found a fantastic pod cast by Lawrence Krause called ‘Origins’. He interviews some really big hitters.
This one is with Alan Guth and there’s a lot of discussion about Inflation and Guth describes it as the being born out of GR and QFT.
They even touch on time right at the end, but IMV completely lose the plot 😀
https://podcasts.apple.com/gb/podca...-lawrence-krauss/id1467481703?i=1000559801354
This one is with Alan Guth and there’s a lot of discussion about Inflation and Guth describes it as the being born out of GR and QFT.
They even touch on time right at the end, but IMV completely lose the plot 😀
https://podcasts.apple.com/gb/podca...-lawrence-krauss/id1467481703?i=1000559801354
If Mr. Bonsai thinks they lose the plot regarding time, it must be bad!
P.S. That podcast is two and a half hours long and you got to the end?
A work of art has landed on the Moon, but not for the first time...
https://edition.cnn.com/2024/02/22/style/jeff-koons-moon-phases-odysseus-landing
https://edition.cnn.com/2024/02/22/style/jeff-koons-moon-phases-odysseus-landing
Attachments
If Mr. Bonsai thinks they lose the plot regarding time, it must be bad!
P.S. That podcast is two and a half hours long and you got to the end?
Yes. I listened to the whole thing!
Re the time bit (nice little unnecessary dig there Galu 😉), Sean Carrol has apparently come up with some 2 pronged arrow of time thing to try to explain the early expansionary epoch, but elsewhere in the podcast Guth talks about how the expansion of the universe is fine tuned to 1 part in 10^14 (😳).
I find myself in two minds here. Philosophically, you can just say ‘we are where we find ourselves’ and shrug our shoulders and say ‘so what?’
Or, if it’s that finely tuned it can’t be luck, but instead, it’s 1 part in 10^14 because it is the result of a very fundamental underlying mechanism.
What do you think? Pure luck or something deeper?
It this Sean Carrol banging on about the increase in entropy due to the second law of thermodynamics again? 😱
Why was entropy so small at the Big Bang? Was there time before the Big Bang? Is that why the arrow of time is "2 pronged"?
I read that the likelihood of our current Universe having low energy initial conditions of this kind, and not any other kind, is around one in 10 to the 10 to 124 (1:10^10^124).
You'll be lucky to get anything deeper out of me! 🤓
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A cyclical model is one where the Universe is born and born again.
A previous, cold dark empty universe like the one which lies in our far future could have been the source of our very own Big Bang.
This is a convenient way for cosmologists to explain why the Universe could arise from almost nothing, i.e., after all the matter in a universe has been consumed into black holes, which have in turn boiled away into photons.
Penrose's theory is "Conformal Cyclic Cosmology" which explains why the very same state can be a cold, empty universe from one perspective and a hot dense universe from another. His theory relies on "conformal rescaling" which goes way above my head so I'll refer you to my information source: https://www.bbc.com/future/article/20220105-what-existed-before-the-big-bang
Hope that helps!
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Physicists have detected the pull of gravity on the microscopic scale with the help of brass weights attached to an electrical bicycle wheel!
https://www.theguardian.com/science/2024/feb/23/quantum-physics-microscopic-gravity-discovery
They recorded a minuscule gravitational tug of 30 quintillionths of a newton on a particle less than a millimetre wide, paving the way towards an understanding of the nature of gravity in the quantum realm.
You can now feel free to say "on your bike" to any experimental physicist you may meet! 😊
https://www.theguardian.com/science/2024/feb/23/quantum-physics-microscopic-gravity-discovery
They recorded a minuscule gravitational tug of 30 quintillionths of a newton on a particle less than a millimetre wide, paving the way towards an understanding of the nature of gravity in the quantum realm.
You can now feel free to say "on your bike" to any experimental physicist you may meet! 😊
Please explain "on your bike" to non english natives. I presume there is a joke, some hidden meaning.
Those are of course really small numbers, but it seems to me it's easier to detect an alternating signal than a static signal, thus this is an advantage over a Cavendish-like experiment that has been traditionally used.
The article didn't say (or I missed it) how fast the wheel was spinning. I'm thinking the faster the better.
In the following article, there's mention of the three equally spaced brass masses on the rim of the electric wheel driving a "27 Hz mode".
https://www.science.org/doi/10.1126/sciadv.adk2949
The objective is for the brass masses to gravitationally drive the motion of a tiny particle which is magnetically levitated.
"We demonstrate the detection of a 30 aN gravitational signal at 27 Hz." - That's the conclusion!
However, to me, the experimental manipulations are no more than gobbledygook. 😵
Indeed. It is much easier to amplify AC than DC. That is the idea in precision dc chopper amplifiers.
Chop the DC signal at a quite high frequency ( 100kHz ), narrow band amplify, synchronous detect.
What is the difference between this and Cavendish's experiment to weigh the Earth? We know two lumps of matter attract each other.
Perhaps this?
"Because quantum coherence is easily lost for increasing system size, it is important to isolate gravity as a coupling force for as small objects as possible."
"In magnetically levitated systems, this pathway of decoherence is largely removed."
P.S. Quantum decoherence is the loss of quantum coherence, the process in which a system's behaviour changes from that which can be explained by quantum mechanics to that which can be explained by classical mechanics.
"Because quantum coherence is easily lost for increasing system size, it is important to isolate gravity as a coupling force for as small objects as possible."
"In magnetically levitated systems, this pathway of decoherence is largely removed."
P.S. Quantum decoherence is the loss of quantum coherence, the process in which a system's behaviour changes from that which can be explained by quantum mechanics to that which can be explained by classical mechanics.
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