There are only about 80,000 old giant sequoias left in California. After years of drought, roughly 10% of these enormous trees died in a massive fire in 2020. The future for them does not look good.
But I just learned that there are about 500,000 younger giant sequoias and closely related coastal redwoods in the UK!
They were first introduced in 1853 by the Scottish grain merchant Patrick Matthew. Later that year, the famous plant collector William Lobb brought over many more. Because of their rarity and novelty, these trees were very expensive. But that worked in their favor: they became a symbol of wealth in Victorian Britain. People planted them at the entrances of grand houses and estates, along avenues, and in churchyards and parks.
The map shows just 4949 of the giant sequoias in the UK. Surprisingly, they thrive there, despite the climate being very different from that in their native range - the Sierra Nevada mountains, dry in the summer and snowy in the winter.
They are now the largest trees in the UK! A new study shows each tree sequesters carbon at the rate of 85 kilograms per year, on average. This is very high for trees, and sequoias keep growing for centuries. People are wanting to plant more.
Invasive species - or wonderful rescue of a species that might otherwise go extinct? Evolution does its thing regardless of our value judgements, but what we do affects it. Long ago, giant sequoias were common in North American and Eurasian coniferous forests. By the last ice age, their range had shrunk to a small area in California. Now, thanks to humans, they are spreading again.
Highlights
• Retroactive interference causes forgetting by the competition of two memory engrams
• Forgotten engrams can be expressed or updated by reexposure to training cues
• Artificial reactivation of engram cells rescues interference-induced forgetting
• Interference is an active process that requires the activation of the suppressed engram
these findings indicate that retroactive interference modules engram expression in a manner that is both reversible and updatable. Inference may constitute a form of adaptive forgetting where, in everyday life, new perceptual and environmental inputs modulate the natural forgetting process.
The Voyager 1 and 2 spacecraft sent back hundreds of color pictures as they flew by Jupiter and Saturn. But they could only transmit 14 kilobytes per second! So they used a highly efficient error-correcting code: the Golay code.
This is a 24-bit code. The first 12 bits convey the message, and the rest are computed from those. Up to 3 of the 24 bits can be wrong and you can still figure out what was intended! Up to 7 can be wrong and you can still know there was an error!
This image by @gregeganSF shows how it works. This shape, an icosahedron, has 12 vertices. There are also 12 pentagons inside this shape. Your first 12 bits say which pentagons to light up. 0 means "leave it dark" and 1 means "light it up". Your second 12 bits say which vertices to light up.
The second 12 bits are computed from the first 12 using this trick:
If you light up a single pentagon, then you only light up the vertices that don't contain that pentagon! What if you light up a bunch of pentagons? Then you use addition mod 2. You work out which vertices get lit up for each pentagon you light up. You think of those results as 12-bit strings. Then you add them up mod 2.
The last part may sound complicated, but it's a common trick, called a "linear code". What's special about the Golay code is its connection to the icosahedron. This gives it remarkable features, which I explain here:
@johncarlosbaez@gregeganSF
The latest NASA missions use the same coding scheme as 5G physical layer: LDPC (low-density parity-check) code.
Among capacity-approaching codes
LDPC approaches the Shannon limit more closely than any other class of codes.
LDPC was invented by Robert Gallager in 1961 and mostly forgotten (“a bit of 21st-century coding that happened to fall in the 20th century”). LDPC uses sparse Tanner graph.
I have so many questions about what just happened with Voyager 2. But let's review:
On August 20, 1977, Voyager 2 was launched from Earth.
In December 1977, it entered the asteroid belt.
In June 1978, its main radio receiver failed. Since then it's been using the backup receiver!
On July 9, 1979, it flew past many of Jupiter's moons, made its closest approach to Jupiter, and took tons of beautiful pictures.
On August 26, 1981 it shot past Saturn and took tons of beautiful pictures.
On August 25, 1989 it shot past Neptune and took tons of beautiful pictures.
On November 5, 2018 it crossed the heliopause and entered interstellar space, 120 times farther from the Sun than we are.
On July 18, 2023, it overtook Pioneer 10 and became the second farthest man-made object from the Sun.
3 days later, some idiot sent a command that pointed its high gain antenna 2 degrees away from Earth. HOW EXACTLY DID THIS HAPPEN?
On August 4, 2023, NASA used its most high-powered transmitter to successfully command Voyager 2 to reorient towards Earth, resuming communications. HOW WAS THAT POSSIBLE?
Voyager 2 is now 133 AU away. How can you "shout" across such a distance and attract the attention of someone who is not looking in your direction? That's very far. It takes light about 18 hours to travel that far.
@johncarlosbaez
Command File Errors (CFE) are not rare in space operations.
They don't just type in the command and press enter. They create a command file that contains the command sequence. It's planned, tested, reviewed and finally approved in command conference before it's sent to ops and radiation.
What @gregeganSF said seems plausible. Someone in ops somehow sent the wrong command with right numbers.
Can you roll a ball with exactly enough energy to reach the top of a dome, and have it reach the top in a finite amount of time?
I'm going to idealize the hell out of this problem so we can easily study it using math. So: no friction, no air resistance... in fact, NONE of the sneaky stuff you're probably thinking about!
The problem is still tricky. For an ordinary dome the answer is no. If the ball has just enough energy to make it to the top, it rolls slower and slower as it gets near the top, in such a way that it never reaches the top.
But if the dome has a carefully chosen shape, the ball can reach the top in a finite time! This was pointed out by the philosopher John D. Norton, so it's called "Norton's dome".
Norton was mainly interested in another freaky feature of his dome. Say you start with a ball at rest on top of the dome. Then there are many solutions of Newton's law
F = ma
In one the ball remains at rest on top of the dome. But in others, it starts to roll down the dome in some arbitrary direction! Moreover it can start rolling at any time.
If you change the shape of the dome ever so slightly, this probably won't work. It needs to be crafted with perfect accuracy. So this is basically just a mathematical curiosity.
Math folks will realize what's going on: not every first-order differential equation has a unique solution given its initial value. But Norton, being a philosopher of physics, manages to make this a lot more exciting than a typical textbook treatment of the Picard–Lindelöf theorem. 🙃
That word theory gets thrown around a lot. Some of my colleagues hold it to a really high bar whereas others use it pretty interchangably with hypothesis testing.
There’s an early phase of research that I’m not sure how to label. It’s not so much about levels, but something else. Here’s an example: what would you call the contribution of Copernicus to planetary motion? Ptolomy had these elaborate descriptions of everything revolving around the earth as cycles and epicycles to make up for wonky trajectories, and Copernicus came along and demonstrated that it all becomes a lot simpler if it’s all revolving around the sun. “Theories” of why the planets revolve as they do (Newton’s gravity and Einstein’s bending space time) came later.
Was Copernicus’s contribution a theory, replotting the data in a more sensible way, or something in between? Whatever it was, it was important, and it led to all that followed. But what do we call it (aka how do we regard it)?
@NicoleCRust
It sounds like you are seeking "effective theory".
Effective theory is a theory that explains the observations or mechanism phenomena well, but is not considered fundamental. Classical theory of gravity is a great effective theory, but it's not fundamental theory (anymore).
In the same way the current field theories are considered "effective" theories at the low energy limits. There must be something else that explains all energy ranges.
The notes in the major scale are spaced in a funny way. Look at the white keys on the piano: some have black keys between them, other don't. But you can understand the major scale using the circle of fifths. Start with C. Go up a fifth and you get G. Go up another fifth and you get D. Go up another and you get A. Go up another and you get E. Go up another and you get B. Go up another and you get F. And these are the notes in the C major scale!
That sounds like satisfying explanation. But it's a lie!
I lied only at the end. When you go up a fifth from B, you don't get F. You get F#. So you don't get the notes in the major scale. You get the notes in another scale, called Lydian!
This is why George Russell argued that Lydian is more fundamental than the major scale.
Russell is the theorist who helped Miles Davis switch to a new style of jazz in Kind of Blue - the best-selling jazz album of all time. In his book The Lydian Chromatic Concept of Tonal Organization, Russell tried to redo harmony theory from the ground up. For a great explanation of Russell's ideas, watch the video.
But here's something else. In the modern system of modes, if you start the major scale at different points you get different scales or 'modes' called Ionian (major), Dorian, Phrygian, Lydian, Mixolydian, Aeolian (minor) and Locrian.
But in the old system of modes used in Gregorian chants, Ionian and Aeolian were missing!
That's right: the major and minor scales, which we consider the most important, were not on the list! They were only added in 1547 by a theorist named Heinrich Glarean.
So maybe major wasn't considered as important as Lydian???
With just 3 days of ‘vacuuming’ airborne eDNA in a Danish forest, we detected 64 animals - domestic, exotic pets and.. over 50 species of wild birds, mammals and amphibians! This was our first exploration of airborne eDNA in a natural setting and we were especially surprised by the high number of bird taxa detected.
@Loukas@biodiversity
The ability to detect tiny DNA traces is already a problem in the forensic science. Their value as evidence is increasingly questionable, but they are treated as solid evidence in the court.
It used to be that suspects sleeve touching the hand rail that victim was touching could not transmit detectable traces of DNA, but as technology advances it now happens.
I suspect that the same applies to eDNA. If someone who works in the Copenhagen Zoo is jogging trough the forest, it may seem like pandas, lions and giraffes are there.
Did you know that Einstein was the only top physicist who believed that light (em-radiation) was quantized between 1905-1922 until Compton experiments demonstrated it.
Einstein's 1905 paper 'On a Heuristic Viewpoint Concerning the Production and Transformation of Light' says "[light ray] consists of a finite number of energy quanta that are localized in points in space, move without dividing, and can be absorbed or generated only as a whole."
Everybody rejected this idea, (including Plank) but accepted one of the results (explaining photoelectric effect) and gave him Nobel price for it.
This is why Einstein is considered being head above others.
I’ve noticed a strong alignment between those who think that the computer metaphor for the brain makes little sense and those who’ve thought about how the brain might give rise to emotion.
As much as I love all the progress happening in NeuroAI to push our understanding of perception, memory & intelligence forward, I very much think they are right - there’s a crucial swath that doesn’t seem to fit with that agenda.
I'm surprised about the idea that emotions would be computationally complex, or that they compute anything complex.
Any support for the hypothesis?
It seems to me that emotions are just limited bandwidth internal sensations, we react to them habitually unless we exercise some control over them.
Being vague, unconscious, arbitrary, hard to describe, or pin down rules, does not automatically imply computationally complex. You can shuffle deck of cards 8×10^67 ways. That does not mean card shuffling is computationally complex process.
Can you point me towards emotion research or cognitive philosophy that indicates that emotions are computationally so complex that we need a new paradigm? What you two are suggesting seems completely novel idea and concern.
Everything I have read about emotion research indicates that emotions complex only in the other senses of the word. Emotional patterning is attached to many/most other modalities, but that does not suggest that emotional processing would be computationally intractable or even the most difficult cognitive process.
My understanding of the research is that we find emotions "complex" because we don't have direct access to causal connections that influence our core affect and it alters our behavior unconsciously.
(this i have learned and remember)
The processing of affective state is a mostly automatic process called "evaluation", a fast and simple analysis in which something is judged (often unconsciously). This evaluation diffuses to other processes and modulate them (complex results from simple continuous process).
"Having to make a care decision as a loved one's health care proxy" might feel complex because this simple affective evaluation leaves a incoherent conflicting mess behind.
Isn't therapy a way to use other cognitive processes to deal with the mess our computationally simple and primitive emotional system can't handle?
We conclude that Betelgeuse
should currently be in a late phase (or near the end) of the core car-
bon burning. After carbon is exhausted in the core, a core-collapse leading to a supernova explosion is expected in a few tens years.