Ultimate space simulation software

 
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23 Jan 2022 18:14

That's awesome. Great animation. Not surprisingly, although the wave is somewhat intensified, it is quite nonuniform and does not come into a sharp focus at the antipode, thanks to the effects of Earth's oblateness and probably reflections as well.
True that.
There's now a beautiful visualization about this, made by Angel Amores:

https://youtu.be/oXa-QsSYpfg

[Source: https://twitter.com/an_amores/status/1484516695087759363]

You can see a simulated atmospheric pressure wave traveling across the globe from Tonga.
A few things to comment here:

1) The antipodal focusing is not perfectly symmetric and thus the model might have some interesting level of detail. I'm guessing that he has considered the departure from the ideal perfect sphericity of Earth (as Watsisname has commented), the damping and deceleration of the wave when crossing important topographic features (the Himalayas perhaps?) and possibly the Coriolis effect due to the differential motion of the atmosphere at different latitudes due to Earth's rotation (but my guess is that this might be extremely weak since other random winds might have a larger effect on the wave).

2) Another consideration here is the fact that the pressure wave gets a 90º phase shift when reflected against itself in the antipodes, as midtskogen noted with his weather station when he recorded the antipodal rebound as a decrease in pressure followed by an increase (instead of the increase followed by a decrease as in the first wave transit). This can be clearly seen in the simulation as the incoming wave has a blue-yellow color palette that gets inverted in order after the rebound.

3) One awesome thing of this video is that you can see the expected data retrieved from the theoretical simulation overlayed on top of the actual data registered by a few barometers around the world. You can see there that the timing of the wave and its rebounds is precisely predicted as well as the general intensity of each signal. This in my opinion shows how well we actually know the shape of the Earth, the wave propagation properties of our atmosphere and the energy involved in the eruption. I hope that almost all the fluctuations seen in the data come from local pressure variations unrelated to the Tonga event. But in any case we will see more detailed models in the next months.


This is also an awesome visualization of the barometric data gathered in Switzerland:
Image
[Source: https://twitter.com/myweather_ch/status/1484150854236135428]

The S1 mark shows the first wave passing over Switzerland, followed some hours later by the rebound (N1). Then the wave rebounded once again at Tonga and came back (S2) and rebound at the antipodes for a second time (N2). You can clearly see the barometric signal of even the fourth rebound after 5 days of traveling across the globe several times.

Another thing I liked about this data is the way it is visualized. The actual barometric signal is the bottom graph. You can see the wave decaying as expected after each passage. You can see that the peaks in pressure are noticeable but if we wish to make them stand more strongly above the noise (other pressure fluctuations registered that have nothing to do with the shock wave from Tonga), then we must increase the contrast between low values and large values. We could mathematically do that by multiplying the signal by some number (for example by ten), which would enlarge the differences between peaks and valleys in the signal. But this is problematic because the peaks in the noise will also be enlarged and we will end up noticing more noise than before. A nice technique is to perform the first derivative of the signal below. This is a neat trick. By doing that mathematically you are looking for changes in pressure and not the pressure itself. You can perform a second derivative over the signal to get knowledge about the curvature of the signal as we approach a drastic peak. That's exactly what they do in the first and second graph. You can clearly see the peaks as prominent lines on those graphs.

I'm using this data as an excuse to show the technique, which I think is quite neat, and because now we can understand how satellite data can be processed to show the wave traveling around the world quite clearly.

By performing a first derivative with respect to time on the IR images (apparently infrared shows changes in pressure more clearly than optical images) taken GOES-West Satellite (which is geostationary) we can clearly see the wave as if the atmosphere was a giant pond:

https://i.imgur.com/lvxhFUX.mp4
[Source: https://twitter.com/MathewABarlow/status/1484907406182301697]

The same thing can be done with IR images from EUMETSAT (another geostationary satellite) to reveal the wave as it converges in the antipodes as clearly as possible:
https://i.imgur.com/e7bJhud.mp4
[Source: https://github.com/mathewbarlow/animations]
I love the way you described this technique of increasing the signal without raising the noise level, it actually reminds me of what we do in photography to increase the SNR rather than outright increasing the ISO (an analogy to your multiplication method) which also increases the noise.  The derivative method you outlined is very similar to the stretching technique we use to increase the dynamic range of an image without increasing the noise floor.
 
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26 Jan 2022 04:43

Tsunamies are rare events, and can be predicted in advance, though rarely more than a few hours.  I think a warning system and evacuation plans are the most realistic approach.  For NY the risk of a tsunami is extremely low, though.

Mitigation for sea level rise and coastal erosion might not be so hard either.  Since these are slow processes over decades, it might be sufficient to account for these things in development plans.  Places lacking higher ground or firm ground are more of a concern, and relocation might be unavoidable.  Even with modern technology it would be difficult to save Doggerland.  Climate change can also trigger relocation.  Millions in northern America and northern Europe live on borrowed land.  We must assume that the ice will return, but it's a change that takes many centuries, longer than most things that we build are meant to last.

Coastlines are not static, and we can't make them so.
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27 Jan 2022 01:35

They aren't static and the tricky part is that sea level rise is occurring at different rates in different parts of the world.  Some of the more susceptible locations on the east coast already experience sunny day flooding.  And there are island nations in the Pacific who really are living on finite borrowed time.

In other news, I found this-- it looks like a new magnetar may have been found?

https://twitter.com/i/events/1486452209357230082

Mysterious object 4,000 light-years away from Earth releases giant bursts of energy

Unlike anything ever seen in space discovered by astronomers!
 
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10 Feb 2022 03:05

Big news!

Big step towards controllable nuclear fusion by Tokamak fusion reaction lasted for 5 seconds, 59 megajoules of energy produced (enough to light up a home for half a day)

https://twitter.com/i/events/1491539482973249539
 
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11 Feb 2022 00:03

Big step towards controllable nuclear fusion by Tokamak fusion reaction lasted for 5 seconds, 59 megajoules of energy produced (enough to light up a home for half a day)
Yes, and also a reminder that the world is still 30 years away from being powered by nuclear fusion.
(and through the way it's presented that people still believe "climate catastrophe" is a real, imminent thing - sigh)
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11 Feb 2022 13:03

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26 Feb 2022 23:33

https://twitter.com/i/events/1496444634091950080

 
Brain activity of dying man suggests our lives really do flash before our eyes as we die
+ Neuroscientists recorded the brain activity of an 87-year-old as he died from a heart attack + It is the first time ever that scientists have recorded the activity of a dying human brain, according to the team + Brain waves at the time of death were similar to those occurring during memory retrieval + This supports the 'life recall' theory – that our whole life flashes before our eyes as we die
 
Neuroscientists recorded the brain activity of an 87-year-old as he died from a heart attack while using electroencephalography (EEG) to treat his seizures + It is the first time ever that scientists have recorded the activity of a dying human brain, according to the team
 
Brain waves at the time of death were similar to those occurring during memory retrieval + This supports the 'life recall' theory – that our whole life flashes before our eyes as we die + The brain may remain active and coordinated during and after the transition to death.
 
'These findings challenge our understanding of when exactly life ends and generate important subsequent questions,' a neurosurgeon said
 
'Something we may learn from this research is: although our loved ones have their eyes closed and are ready to leave us to rest, their brains may be replaying some of the nicest moments they experienced in their lives'
 
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26 Feb 2022 23:36

https://twitter.com/i/events/1496545201434857481

 
Scientists warn world's first octopus farm could be an ethical and environmental disaster
Spanish company Nueva Pescanova beat rival companies in Mexico and Japan to perfect the conditions needed for industrial-scale breeding. But not everyone is convinced.
 
 
 
Previous efforts to farm octopus have struggled with high mortality, while attempts to breed wild-caught octopus ran into problems with aggression, cannibalism and self-mutilation 4/6
 
Since the 2020 documentary 'My Octopus Teacher' captured the public imagination with its tale of a filmmaker's friendship with an octopus, concern for their wellbeing has grown 5/6
 
Last year, researchers at the London School of Economics concluded from a review of 300 scientific studies that octopus were sentient beings capable of experiencing distress and happiness, and that high-welfare farming would be impossible https://reut.rs/3Ig8kFS 6/6
 
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01 Mar 2022 04:03

https://twitter.com/i/events/1498282348936409093

The illusion of reality (from a neurologist's perspective.)
 
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02 Mar 2022 04:50

Last year, researchers at the London School of Economics concluded from a review of 300 scientific studies that octopus were sentient beings capable of experiencing distress and happiness, and that high-welfare farming would be impossible
I don't think this makes sense.  There are many, many species of octopuses, so how is this different from saying that there are studies concluding that mammal are sentient and capable of experiencing distress and happiness, and that high-welfare farming is impossible?  Which most would disagree with (or at least ignore), despite acknowledging that farming of the human kind of mammals certainly would be unethical.
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02 Mar 2022 17:09

Last year, researchers at the London School of Economics concluded from a review of 300 scientific studies that octopus were sentient beings capable of experiencing distress and happiness, and that high-welfare farming would be impossible
I don't think this makes sense.  There are many, many species of octopuses, so how is this different from saying that there are studies concluding that mammal are sentient and capable of experiencing distress and happiness, and that high-welfare farming is impossible?  Which most would disagree with (or at least ignore), despite acknowledging that farming of the human kind of mammals certainly would be unethical.
Well, they separate higher level creatures like octopi and elephants from lower intelligence creatures like cows and sheep and such.
Although I find the line very subjective....of course cows and sheep experience distress and happiness, so I'm not exactly sure what is meant by sentience.  If they mean complex emotions that's a different story....elephants mourn and bury their dead and return to their burial sites every year.  
 
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03 Mar 2022 01:24

I'm not exactly sure what is meant by sentience
There is no distinct line between instinct and consciousness.  Sentience is more a human subjective feeling for animal behaviour (and expression) that we can relate to.
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03 Mar 2022 02:29

I've been looking stuff up on Octopi.

https://en.wikipedia.org/wiki/Octopus#N ... and_senses

Intelligence
Main article: Cephalopod intelligence
[img=170x198]https://upload.wikimedia.org/wikipedia/commons/thumb/a/a4/Oktopus_opening_a_container_with_screw_cap_02_%28cropped%29.jpg/170px-Oktopus_opening_a_container_with_screw_cap_02_%28cropped%29.jpg[/img]

Octopus opening a container by unscrewing its cap
Octopuses are highly intelligent.[sup][96][/sup] Maze and problem-solving experiments have shown evidence of a memory system that can store both short- and long-term memory. Young octopuses learn nothing from their parents, as adults provide no parental care beyond tending to their eggs until the young octopuses hatch.[sup][67][/sup][sup]: 75 [/sup]
In laboratory experiments, octopuses can readily be trained to distinguish between different shapes and patterns. They have been reported to practise observational learning,[sup][97][/sup] although the validity of these findings is contested.[sup][96][/sup] Octopuses have also been observed in what has been described as play: repeatedly releasing bottles or toys into a circular current in their aquariums and then catching them.[sup][98][/sup] Octopuses often break out of their aquariums and sometimes into others in search of food.[sup][93][/sup][sup][99][/sup][sup][100][/sup] The veined octopus collects discarded coconut shells, then uses them to build a shelter, an example of tool use.[sup][95][/sup]

https://en.wikipedia.org/wiki/Cephalopod_intelligence

Protective legislation
[img=220x154]https://upload.wikimedia.org/wikipedia/commons/thumb/7/76/Octopus.jpg/220px-Octopus.jpg[/img]

An octopus in a zoo.
Due to their intelligence, cephalopods are commonly protected by animal testing regulations that do not usually apply to invertebrates.
In the UK from 1993 to 2012, the common octopus (Octopus vulgaris) was the only invertebrate protected under the Animals (Scientific Procedures) Act 1986.[sup][46][/sup]
Cephalopods are the only invertebrates protected under the 2010 European Union directive "on the protection of animals used for scientific purposes".[sup][47][/sup]
In 2019, some scholars have argued for increased protections for cephalopods in the United States as well.[sup][48][/sup]

https://en.wikipedia.org/wiki/Animal_cognition

https://en.wikipedia.org/wiki/Animal_consciousness

Tool use
[img=220x165]https://upload.wikimedia.org/wikipedia/commons/thumb/4/47/Octopus_shell.jpg/220px-Octopus_shell.jpg[/img]

A small coconut octopus (4–5 cm in diameter) using a nut shell and clam shell as shelter.
The octopus has repeatedly been shown to exhibit flexibility in the use of tools.
At least four individuals of the veined octopus (Amphioctopus marginatus) have been observed retrieving discarded coconut shells, manipulating them, transporting them some distance, and then reassembling them for use as shelter.[sup][34][/sup] It is surmised that the octopuses used bivalves for the same purpose before humans made coconut shells widely available on the sea floor.[sup][35][/sup][sup][36][/sup] Other sea creatures construct homes in a similar manner; most hermit crabs use the discarded shells of other species for habitation, and some crabs place sea anemones on their carapaces to serve as camouflage. However, this behavior lacks the complexity of the octopus's fortress behavior, which involves picking up and carrying a tool for later use. (This argument remains contested by a number of biologists, who claim that the shells actually provide protection from bottom-dwelling predators in transport.[sup][37][/sup]) Octopuses have also been known to deliberately place stones, shells, and even bits of broken bottles to form walls that constrict their den openings.[sup][38][/sup]
In laboratory studies, Octopus mercatoris, a small pygmy species of octopus, has been observed to block its lair using plastic Lego bricks.[sup][39][/sup]
Smaller individuals of the common blanket octopus (Tremoctopus violaceus) hold the tentacles of the Portuguese man o' war (whose venom they are immune to), both as means of protection and as a method of capturing prey.[sup][40][/sup]
Problem-solving ability
The highly sensitive suction cups and prehensile arms of octopuses, squid, and cuttlefish allow them to hold and manipulate objects. However, unlike vertebrates, the motor skills of octopuses do not seem to depend upon mapping their body within their brains, as the ability to organize complex movements is not thought to be linked to particular arms.[sup][41][/sup]
Cephalopods can solve complex puzzles requiring pushing or pulling actions, and can also unscrew the lids of containers and open the latches on acrylic boxes in order to obtain the food inside. They can also remember solutions to puzzles and learn to solve the same puzzle presented in different configurations.[sup][42][/sup]
  • Octopus opening a container with a screw cap
Captive octopuses require stimulation or they will become lethargic; this typically takes the form of a variety of toys and puzzles.[sup][43][/sup] At an aquarium in Coburg, Germany, an octopus named Otto was known to juggle his fellow tank-mates around, as well as throw rocks to smash the aquarium glass. On more than one occasion, Otto even caused short circuits by crawling out of his tank and shooting a jet of water at the overhead lamp.[sup][44][/sup]

Additionally, cephalopods have been shown to have the capacity for future planning and reward processing after being tested with the Stanford marshmallow experiment.[sup][45][/sup]
 
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03 Mar 2022 02:36

I'm not exactly sure what is meant by sentience
There is no distinct line between instinct and consciousness.  Sentience is more a human subjective feeling for animal behaviour (and expression) that we can relate to.
Some of these tests performed on octopi are fascinating, I knew cephalopods were highly intelligent, but this is a higher level of intelligence than I'm used to hearing about from any invertebrate species.
 
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14 Mar 2022 00:43

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