Following the collapse of Arecibo, China opened up FAST (Five-Hundred-Meter Aperture Spherical Radio Telescope) to astronomers worldwide.
https://en.wikipedia.org/wiki/Five-hundred-meter_Aperture_Spherical_Telescope
The latest news is that an extension to FAST will integrate 24 secondary 40 m antennas installed within 5 km of the FAST site.
The 'FAST Core Array' will increase the telescope's angular resolution and is estimated to be completed and put into operation in 2027.
https://en.wikipedia.org/wiki/Five-hundred-meter_Aperture_Spherical_Telescope
The latest news is that an extension to FAST will integrate 24 secondary 40 m antennas installed within 5 km of the FAST site.
The 'FAST Core Array' will increase the telescope's angular resolution and is estimated to be completed and put into operation in 2027.
Cables from the six towers visible in the FAST image above support the "feed cabin" where the radio waves are focused.
Although the 500 m dish as a whole can't move, the shape of its surface is changeable. This alters the focus point of the radio waves and the suspended feed cabin moves around the surface of the dish to follow it. In this way the telescope is able to observe sources which lie 40° away from the zenith.
Although the 500 m dish as a whole can't move, the shape of its surface is changeable. This alters the focus point of the radio waves and the suspended feed cabin moves around the surface of the dish to follow it. In this way the telescope is able to observe sources which lie 40° away from the zenith.
Needless to say that the receivers are ultra low noise.
Presumably parametric amplifiers, cooled at near 0°K.
Presumably parametric amplifiers, cooled at near 0°K.
Trawling around, I learn that the largest receiver system in FAST is cryostat-cooled with a noise temperature of under 7 K.
There are several pertinent scientific papers to which I don't have direct access - not that I'd understand them anyway!
Call that a telescope? 8 arc second resolution? 10cm minimum wavelength?
THIS is a telescope! The ALMA array in Chile. 😎
https://en.wikipedia.org/wiki/Atacama_Large_Millimeter_Array#
They can spread the mm. dishes over 15km to form a huge interferometer:
I was stuck for a read yesterday at my local coffee shop, so picked up this Brian Cox tome at the Southsea local library.
All that glisters is not gold...
Started quite interesting:
I was hoping for a few matrices describing observables, rather than any fruitless attempts to describe what quantum particles look like.
But NO. Dubiousness from start to finish:
Protons don't decay into neutrons. Energetically forbidden!
It got worse:
It's not h, you dummy. It's h(bar) in the Planck mass. SQRT h(bar)c / G, mp being proton mass. Then the maximum mass of a White Dwarf comes out to 1.44 Sols mass, which is the Chandrasekhar Mass.
Above that it's Neutron stars up to between 2 or 3 sols mass, which Arecibo was good at finding. After that, we are talking Black Holes.
Very unimpressed with this book. Tempted to write in the margin. In pencil, of course. I do have a critical faculty. 🙂
THIS is a telescope! The ALMA array in Chile. 😎
https://en.wikipedia.org/wiki/Atacama_Large_Millimeter_Array#
They can spread the mm. dishes over 15km to form a huge interferometer:
I was stuck for a read yesterday at my local coffee shop, so picked up this Brian Cox tome at the Southsea local library.
All that glisters is not gold...
Started quite interesting:
I was hoping for a few matrices describing observables, rather than any fruitless attempts to describe what quantum particles look like.
But NO. Dubiousness from start to finish:
Protons don't decay into neutrons. Energetically forbidden!
It got worse:
It's not h, you dummy. It's h(bar) in the Planck mass. SQRT h(bar)c / G, mp being proton mass. Then the maximum mass of a White Dwarf comes out to 1.44 Sols mass, which is the Chandrasekhar Mass.
Above that it's Neutron stars up to between 2 or 3 sols mass, which Arecibo was good at finding. After that, we are talking Black Holes.
Very unimpressed with this book. Tempted to write in the margin. In pencil, of course. I do have a critical faculty. 🙂
FAST is a single large dish focusing on a 'single' receiver whereas ALMA is an interferometer consisting of many dishes focusing on their own receivers.
FAST observes in the centimetre to metre wavelength range. ALMA observes at smaller wavelengths of 0.3 mm to about 1 cm.
ALMA's resolution is given as 10 milliarcseconds, while FAST's is 50 arcseconds at 10 cm wavelength. For comparison, the unaided human eye has a resolution of about 60 arcseconds.
It should be obvious that FAST and ALMA will be investigating different phenomena - a matter of horses for courses as you might say, Steve!
For example, FAST is currently observing pulsars while ALMA is observing distant galaxies.
And I am observing the mysterious planet Uranus! Its moons are considered to maybe harbour life...
https://www.bbc.co.uk/news/articles/cgk1333k0ypo
Flippin' cold out tonight. My platform of choice for my Nikon D60, f1.8 35mm ISO 800 and tripod was a solidly constructed but frosty Mercedes car. Better than other flimsy car roofs I find... 🙂
First, check out the star chart because it's all about the 6 Ps, Prior Planning an all that:
https://theskylive.com/planetarium?obj=uranus
Hmm, looks easy enough! Can you spot it?
What I got in September, with an annoying full moon:
It's moving retrograde! Liken myself to William Herschel.... 🤣
https://www.bbc.co.uk/news/articles/cgk1333k0ypo
Flippin' cold out tonight. My platform of choice for my Nikon D60, f1.8 35mm ISO 800 and tripod was a solidly constructed but frosty Mercedes car. Better than other flimsy car roofs I find... 🙂
First, check out the star chart because it's all about the 6 Ps, Prior Planning an all that:
https://theskylive.com/planetarium?obj=uranus
Hmm, looks easy enough! Can you spot it?
What I got in September, with an annoying full moon:
It's moving retrograde! Liken myself to William Herschel.... 🤣
Let's compare Prof Cox's diagram with the Feynman diagram you supplied earlier in the thread (p248):
^ Feynman diagram for the beta decay of a neutron into a proton, electron and electron antineutrino via an intermediate W− boson.
They look as if they are telling the same story to me. Am I missing something?
The dispersion & separation of matter and energy within the Universe IS what creates gravity.
It is actually very simple.
However, there is more than our one perceivable Universe.
Repeating 'Big Bangs' could not occur without this FACT.
It is actually very simple.
However, there is more than our one perceivable Universe.
Repeating 'Big Bangs' could not occur without this FACT.
I asked Professor Brian Cox to comment on your FACT.
However, he's still gutted by not writing h over two pi!
Yes, I missed that Cox referred to a proton converting into a neutron while Steve's Feynman diagram referred to a neutron converting into a proton!
Correct. It is possible for a proton to be transformed into a neutron, but you have to supply 1.29 MeV of energy to reach the threshold for that transformation.
In the process of inverse beta decay, an electron antineutrino (v bar) interacts with a proton to produce a neutron and a positron (e+).
(The above Feynman diagram should be read from bottom to top.)
The proton just has to be hit with an antineutrino carrying an energy of more than 1.29 MeV!
I read in Hyperphysics that in the very early stages of the Big Bang when the thermal energy was much greater than 1.29 MeV, we may surmise that the transformation between protons and neutrons was proceeding freely in both directions so that there was an essentially equal population of protons and neutrons.
And I can vouch for the authenticity of the signature! 
https://www.abebooks.co.uk/signed/SIGNED-PORTRAIT-IMAGE-Penrose-Roger-Sir/31643978059/bd
https://www.abebooks.co.uk/signed/SIGNED-PORTRAIT-IMAGE-Penrose-Roger-Sir/31643978059/bd
I read Penrose’s book quite some time ago but I failed to get what he was driving at. I happen to be a big advocate of the quantum mind now. Especially in the context of extended mind theory. But if Penrose believes there’s a gap between classical physics and quantum mechanics he’s only scratching the surface. It’s philosophical, I’ll grant him that.
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I got fascinated by Penrose tilings. A discovery in the 70s.
I was reading Scientific America on a flight to O' Hare Chicago, where I found this.
So interested, as soon as i arrived home, i made tiles ( kites and dards shapes ) to play Penrose tiling.
Winter time damn cold, I remember, my driveway clogged by snowplowers.
https://en.m.wikipedia.org/wiki/Penrose_tiling
I was reading Scientific America on a flight to O' Hare Chicago, where I found this.
So interested, as soon as i arrived home, i made tiles ( kites and dards shapes ) to play Penrose tiling.
Winter time damn cold, I remember, my driveway clogged by snowplowers.
https://en.m.wikipedia.org/wiki/Penrose_tiling
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So, you want to be an Astrophysicist? I have found the Physics "A-Level" extension you want to download and digest. 😎
https://filestore.aqa.org.uk/resources/physics/AQA-7407-7408-TG-A.PDF
I was a bit rusty on what a Parsec is myself, but am now up to speed. 3.2 LY. A parallax of 1 arcsecond across the radius of the Earth's orbit at 1 AU or Astronomical unit.
The VLTA telescope and interferometer is in the news for its image of a humungous unstable red giant with a mass of 2,000 Sols in the Large Megellanic Cloud:
https://gizmodo.com/astronomers-take-remarkably-zoomed-in-image-of-red-supergiant-star-2000527117
I have been looking into White Dwarfs too. We have a nearby one in Proxima Centauri about a Parsec away:
This is where the remarkable Chandrasekhar limit comes in at 1.4 Solar masses:
https://galileo-unbound.blog/2019/01/07/chandrasekhars-limit/
Above 1.4 solar masses, and Oppenheimer worked this out, it would be a Neutron Star, as we have seen:
And after the limit of Neutron degeneracy around 2 to3 solar masses, it's Black Hole time. "Amazing!" as Brian Cox frequently says. 🤣
https://filestore.aqa.org.uk/resources/physics/AQA-7407-7408-TG-A.PDF
I was a bit rusty on what a Parsec is myself, but am now up to speed. 3.2 LY. A parallax of 1 arcsecond across the radius of the Earth's orbit at 1 AU or Astronomical unit.
The VLTA telescope and interferometer is in the news for its image of a humungous unstable red giant with a mass of 2,000 Sols in the Large Megellanic Cloud:
https://gizmodo.com/astronomers-take-remarkably-zoomed-in-image-of-red-supergiant-star-2000527117
I have been looking into White Dwarfs too. We have a nearby one in Proxima Centauri about a Parsec away:
This is where the remarkable Chandrasekhar limit comes in at 1.4 Solar masses:
https://galileo-unbound.blog/2019/01/07/chandrasekhars-limit/
Above 1.4 solar masses, and Oppenheimer worked this out, it would be a Neutron Star, as we have seen:
And after the limit of Neutron degeneracy around 2 to3 solar masses, it's Black Hole time. "Amazing!" as Brian Cox frequently says. 🤣
It was the discovery of pulsars in 1967 that provided the first evidence of the existence of neutron stars.
FAST is currently studying rapidly rotating pulsars (millisecond pulsars) in globular clusters of the Milky Way galaxy.
The observed times of arrival of the pulses from millisecond pulsars are highly regular. Long-term timing observations of millisecond pulsars by FAST has found evidence for nanohertz gravitational waves associated with supermassive black hole binaries: https://phys.org/news/2023-06-scientists-key-evidence-nanohertz-gravitational.html
FAST is currently studying rapidly rotating pulsars (millisecond pulsars) in globular clusters of the Milky Way galaxy.
The observed times of arrival of the pulses from millisecond pulsars are highly regular. Long-term timing observations of millisecond pulsars by FAST has found evidence for nanohertz gravitational waves associated with supermassive black hole binaries: https://phys.org/news/2023-06-scientists-key-evidence-nanohertz-gravitational.html
This is really cool! 😎
The detection of nanohertz gravitational waves explained in comic form!
https://physics.aps.org/articles/v16/116
The detection of nanohertz gravitational waves explained in comic form!
https://physics.aps.org/articles/v16/116
The astronauts in the International Space Station (ISS) are weightless, so how do they weigh themselves to ensure they are remaining healthy?
The quick answer is that they 'mass' themselves using an inertia balance.
You may remember the school wig-wag machine I mentioned at the beginning of the year:
Two spring steel arms support a tray into which masses can be inserted. The tray is set into sideways oscillatory motion and its period of oscillation is measured. The larger the mass m in the tray, the longer the period T of the oscillation. In fact, T ∝√m.
In the ISS's Russian module the astronaut crouches on an apparatus resembling a pogo stick and sets its springs oscillating up and down. Timing the period of oscillation then provides a good estimate of the astronaut's body mass.
The apparatus is called a BMMD (Body Mass Measuring Device).
NASA uses an alternative spring contraption called a SLAMMD (Space Linear Acceleration Mass Measurement Device).
https://www.popularmechanics.com/sp...-astronauts-use-to-weigh-themselves-in-space/
The quick answer is that they 'mass' themselves using an inertia balance.
You may remember the school wig-wag machine I mentioned at the beginning of the year:
Two spring steel arms support a tray into which masses can be inserted. The tray is set into sideways oscillatory motion and its period of oscillation is measured. The larger the mass m in the tray, the longer the period T of the oscillation. In fact, T ∝√m.
In the ISS's Russian module the astronaut crouches on an apparatus resembling a pogo stick and sets its springs oscillating up and down. Timing the period of oscillation then provides a good estimate of the astronaut's body mass.
The apparatus is called a BMMD (Body Mass Measuring Device).
NASA uses an alternative spring contraption called a SLAMMD (Space Linear Acceleration Mass Measurement Device).
https://www.popularmechanics.com/sp...-astronauts-use-to-weigh-themselves-in-space/