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Yesterday the Encampment was fairly quiet, but after the President stopped negotiations with the protestors, an air of doom hung over the pro-Palestinian enclave. In this post I’ll put up some photos, videos, and remarks about the final day of the encampment, and then show what happened this morning.

Here are some photos from yesterday afternoon, the last day (hopefully) of the encampment. The afternoon photos are mine, but the video below is credited to another person.

A panorama of the area. Click to enlarge. The encampment is inside the fence to the right, and there were more than 100 tents there.

A press conference held yesterday on the steps of the administration building by the pro-demonstrator professors. They argued strenuously that we should leave up the encampment. After all, they argued, it’s free speech. Well, it’s also a violation of campus speech codes.  250 of these people signed a petition to the President defending the encampment. They lost.

Photos of the last day of the encampment:

I don’t think the University of Chicago Police Department would like this “Fuck UCPD” sign:

Here are three people being kicked out of the encampment yesterday, apparently for no reason except they “intruded”.  Two of them were harassed by the protesters and given the bum’s rush, while the father of Jonathan (the student who took the film) went in to help them. All three were then hustled out with cries of “Fascists! Go home!”, as you can hear.   Video by Jonathan Zeevi.

But the police left the Jewish banners and flags alone, as they were placed legally. Am Yisrael Chai!

The dismantling was already beginning when I walked to work about 5 a.m. There were campus cops all over the place, chanting and screaming by the Encampers, and loud shouts by the police clearing the area. Two cop cars were parked on the quad. I’ll let the Chicago Maroon give the details:

At approximately 4:25 a.m. on Tuesday morning, less than an hour after encampment organizers concluded their final rally of the evening, several dozen UCPD officers arrived at the main quad to remove the pro-Palestine encampment. The officers’ arrival came on the ninth day of the encampment, after UChicago United for Palestine (UCUP) launched an encampment on the quad outside of Swift Hall at 10 a.m. on Monday, following in the steps of pro-Palestinian groups at numerous other universities that have set up encampments in recent weeks.

Shortly before UCPD officers sweeped [sic] the encampment, two UCPD cars arrived on the main quad. Protesters were informed over a speaker that “the University of Chicago [did] not permit their assembly in this area,” and that they were “hereby notified that [they were] committing criminal trespass by remaining on… private property without permission.”

“Anyone who fails to comply will be criminally charged,” the speaker announced. “Students who fail to comply with this order will be subject to University discipline and immediately placed on leave of absence.”

Protesters, as they had largely returned to their tents to sleep for the night following the rally, had only minutes to comply with orders before UCPD officers entered the encampment. As UCPD officers overturned the encampment’s tents and barriers, protesters chanted in unison, repeating the phrases they had used during their daily rallies over the past week of the encampment. The Cook County Sheriff’s Office was also observed on the scene amidst the raid.

“More than 40,000 dead! You’re arresting kids instead!” Encampment members chanted in a video reviewed and verified by The Maroon from a protester inside the encampment during the sweep.

In an interview shared with The Maroon, an encampment member asserted that “[UCPD] did not give [encampment members] a clear plan for leaving.

“They came in maybe two minutes after the warning,” the encampment member said. “It’s clear that they waited until after the rally was over. We were at our most vulnerable.”

JAC: Isn’t that the best time to clear the encampment? We don’t want protestors fighting the cops, which is a recipe for violence and injury. The Maroon continues:

Protesters could be heard screaming by Maroon staff as the raid went on. At 4:55 a.m., UCPD ordered press, including Maroon staff, to leave the quad. It is currently unclear how many arrests may have been made, or if there were any injuries.

In a Telegram message, UCUP encouraged protesters who had not been at the encampment at the time of the raid to return to campus to demonstrate outside of the quad. Protesters gathered near the S. Ellis Ave entrance to the quad and chanted at the line of police donned in riot gear, who set up yellow barricades to separate themselves from the protesters.

Officers then handed out slips of paper with instructions on departing the encampment to the protesters who had gathered. The slips were entitled “Final Notice to Students Participating in Encampment on Main Quad,” and were not handed to protesters inside of the encampment in advance of the raid.

“The Deans on Call and University of Chicago Police Department (UCPD) have informed you multiple times that your tents and other items are unauthorized. This is your final warning to leave the encampment.

If you fail to immediately leave, you will be arrested by law enforcement for criminal trespass under the Illinois Criminal Code.

Additionally, failure to immediately leave will result in disciplinary action as outlined in the Student Manual. You will also be immediately placed on emergency interim leave of absence from the University. A student who has been placed on emergency interim leave of absence must promptly vacate University housing, leave campus, cannot participate in student and academic program activities, or use any University facilities, and may not return until the student has been authorized to return from the leave and reenroll.”

The University could not be reached for comment.

Here’s a video taken by illegal encamper and posted on SJP Twitter; you’ll have to watch it on YouTube (click on “Watch on YouTube”):

This statement by the President was issued shortly after the Quad was cleared, explaining why the Encampment had to go.

 

A similar statement from our Dean of Students and the VP for Safety and Security:

These next photos and videos were taken by several readers of this site.

The protestors after they’d been pushed out of the quad onto Ellis Avenue. They tried to push back into the Quad, but the cops blocked their entry.

The throughway to the Quad that runs beneath the Administration Building, Levi Hall:

The peeved protestors, deprived of their tents and billboards, shouting at the cops blocking their re-entry into the quad:

More: protestors demanding that the cops answer, “Why are you here?” But of course we know whey they’re here: to enforce campus regulations.

“We love you,” they’re crying, though it’s very strange. They’re trying to push back into the quad, but the cops push back using a yellow plastic fence.

Protestors on one side of the fence; cops on the other.

Here, I’m told, are the infamous Weatherpeople, Bill Ayers and Bernadine Dohrn (circled), who were leaders of the Weather Underground (Ayers was a cofounder). They were arrested years ago, but only Dohrn served a bit of time, They got jobs in Chicago, and lately have been hanging around the Encampment to support its members.

The end, a cleared Quad:

Bye, bye, tents!:

I guess not all the protestors took their tents with them, even though they were allowed to.

And here’s a local report from ABC7 News, mentioning punishment of students (but only those who fail to leave).

What’s next? I doubt that these protesters, who are angry and persistent, will give up.  But they won’t be allowed to camp on the campus any longer, and for a while we may have to show University ID cards to get onto campus.

We’re all wondering if there will be punishments for students and “outsiders.”  The cops didn’t apparently ask for IDs as they expelled the Encampers, so I’m not sure how the University will identify those Encampers for punishment. As the President said above, “Where appropriate disciplinary action will proceed.” I’m not convinced, given the history of these protests, that this will occur. But certainly Students for Justice in Palestine, which was a big part of the Encampment and which was already on a warning from the University, should have its status as a Recognized Student Organization revoked.

Student protests will undoubtedly continue, the Jewish students will try to hold their own in the face of the antisemitism that was part of the Encampment, and that’s one form of division that seems irreparable, especially if Israel eliminates Hamas. (Our students should not suffer because of anything Israel does!)

With the faculty divided as well, will things ever get back to normal here? I’m not sure, as antipathy is rife. And our University has certainly had its brand tarnished.

The Jinx Press site has a bunch of tweets, apparently taken by Encampers. Here are a couple (Jinx is clearly pro-Encampment):

Trashing the camp, shouting, tossing debris at press and bystanders pic.twitter.com/cJYaSL1r3I

— Jinx Press (@JinxPress) May 7, 2024

8am on Tuesday and every trace of the encampment has been cleared. pic.twitter.com/f1AQi2Yfnu

— Jinx Press (@JinxPress) May 7, 2024

It took just three hours from when the UCPD started taking down the camp until the quad was cleared. Kudos to the cops for handling this well and avoiding injury, and also to those workers who had to clean up the mess the protesters left behind.

The Sun is increasing its intensity on schedule, continuing its approach to solar maximum. In just over a 24-hour period on May 5 and May 6, 2024, the Sun released three X-class solar flares measuring at X1.3, X1.2, and X4.5. Solar flares can impact radio communications and electric power grids here on Earth, and they also pose a risk to spacecraft and astronauts in space.

NASA released an animation that shows the solar flares blasting off the surface of the rotating Sun, below.

NASA’s Solar Dynamics Observatory captured these images of the solar flares — as seen in the bright flashes in the upper right — on May 5 and May 6, 2024. The image shows a subset of extreme ultraviolet light that highlights the extremely hot material in flares and which is colorized in teal. Credit: NASA/SDO

Predicting when solar maximum will occur is not easy and the timing of it can only be confirmed after it happens. But NOAA’s Space Weather Prediction Center (SWPC) currently estimates that solar maximum will likely occur between May 2024 and early 2026. The Sun goes through a cycle of high and low activity approximately every 11 years, driven by the Sun’s magnetic field and indicated by the frequency and intensity of sunspots and other activity on the surface. The SWPC has been working hard to have a better handle on predicting solar cycles and activity. Find out more about that here.  

Solar flares are explosions on the Sun that release powerful bursts of energy and radiation coming from the magnetic energy associated with the sunspots. The more sunspots, the greater potential for flares.

Flares are classified based on a system similar to the Richter scale for earthquakes, which divides solar flares according to their strength. X-class is the most intense category of flares, while the smallest ones are A-class, followed by B, C, M and then X. Each letter represents a 10-fold increase in energy output. So an X is ten times an M and 100 times a C. The number that follows the letter provides more information about its strength. The higher the number, the stronger the flare.

Flares are our solar system’s largest explosive events. They are seen as bright areas on the Sun and can last from minutes to hours. We typically see a solar flare by the photons (or light) it releases, occurring in various wavelengths.

Sometimes, but not always, solar flares can be accompanied by a coronal mass ejection (CME), where giant clouds of particles from the Sun are hurled out into space.  If we’re lucky, these charged particles will provide a stunning show of auroras here on Earth while not impacting power grids or satellites.

Thankfully, missions like the Solar Dynamics Observatory, Solar Orbiter, the Parker Solar Probe are providing amazing views and new details about the Sun, helping astronomers to learn more about the dynamic ball of gas that powers our entire Solar System.

The post Solar Max is Coming. The Sun Just Released Three X-Class Flares appeared first on Universe Today.

[This is a follow-up to Monday’s post, going more into depth.]

Among the known elementary particles are three cousins: the electron, the muon and the tau. The three are identical in all known experiments — they have all the same electromagnetic and weak nuclear interactions, and no strong nuclear interactions — except that they have different rest masses:

• electron rest mass: 0.000511 GeV/c2
• muon rest mass: 0.105658 GeV/c2
• tau rest mass: 1.777 GeV/c2

[These differences arise from their different interactions with the Higgs field; to learn more about this, see Chapter 22 of my book.]

Question: How sure are we that these three cousins aren’t actually the same object, seen in three different quantum states?

Quantum States

This is a serious possibility, at first glance. After all, individual atoms have many states, in which they look roughly the same but have different energies — which means, because E=mc2, that they have different rest masses. In Fig. 1 are some of a hydrogen atom’s many possible states; the one of lowest energy is called the “ground state”, and ones with more energy are referred to as “excited states”.

Figure 1: Energy levels of quantum states of a hydrogen atom. The lowest-energy state, at far left, is the ground state; all others are excited states. (The energy, measured in electron-volts and negative, is expressed relative to the amount of energy stored in a proton and an electron when the two are fully separated.) Might the electron, muon and tau similarly be three states of the same object?

In a number of ways, hydrogen atoms in these different states are almost the same; each has zero electric charge, and each contains an electron and a proton. They differ in what the electron is doing, as sketched in Figure 2.

Figure 2: How the electron in hydrogen spreads out in different states. Upper left is the ground state; the other five are examples of excited states. Image from https://en.wikipedia.org/wiki/File:HAtomOrbitals.png

From the outside, though, they seem almost the same; the most obvious difference is that they have different amounts of energy. Might the electron, similarly, be the ground state of a complex object, with the muon and tau being that object’s most easily accessible excited states?

I’ve already mentioned one of the facts in favor of this hypothesis: the three particles’ identical interactions with all fields (except the Higgs field). Another hint that might support the hypothesis is this: when a muon or tau “decays” (i.e. when it transitions, via dissipation, to more stable particles), the outcome always includes an electron. For instance, the muon decays to an electron, a neutrino and an anti-neutrino. Tau decays are more complex, but in the end, an electron is always found among its decay products.

Nevertheless, the hypothesis is definitely wrong, as we can see by carefully comparing atoms, electrons, and protons. I’ll do this in two stages:

• Today I’ll describe what we learn from collisions of these particles.
• Soon I’ll describe what we learn from “spin” — angular momentum carried by a particle.

How to Excite an Atom

Let’s look at two typical ways to excite an atom; there are many others, but these two will do for today.

Shining Light

First, we could shine ultraviolet light (an invisible form of light at slightly higher frequency than visible light) on an atom. If so, we might observe processes such as those sketched in Figure 3: a photon of light strikes the atom in its ground state, and what emerges from the collision is the atom in one of its excited states (possibly plus one or more photons). The simplest possible process involves

• photon + atom in ground state → atom in excited state

The excited atom then reveals itself when, at a later time, short on human scales but often long on atomic scales, it decays back to the ground state,

• atom (excited state) → atom (ground state) + one or more photons

Figure 3: A photon strikes an atom; the atom, absorbing its energy, is kicked it into one of its excited states. The excited state will soon “decay”, emitting one or more photons and dropping back down into the ground state.

If there’s just one photon in the excited state’s decay, that photon has always the same frequency , which is determined in terms of the energy of the excited state minus the energy of the ground state

where h is Planck’s constant. [A nitpick: this formula applies when the excited atom is stationary, and has a small correction from the fact that the atom will be moving slowly after the decay.]

Atomic Collisions

Second, we could slam two atoms in the ground state together. If the speed is high enough, one of the two atoms could come out in an excited state, as sketched in Figure 4.

atom (ground state) + atom (ground state) → atom (ground state) + atom (excited state)

Or both atoms could come out in excited states, though not necessarily the same ones. Again, we would learn which excited states were created by looking at the photons emitted when the atoms transition back down to the ground state.

Figure 4: Two atoms collide, and some of the energy of the collision kicks one of them into an excited state. The excited state subsequently decays just as in Figure 3. Could We Excite an Electron?

Let’s imagine trying similar tricks just like this on the electron. We could shine high-energy light on the electron, or we could slam electrons together, seeing if we could turn an electron into a muon or a tau.

Shining Light

If a muon is an electron’s excited state, we could shine light waves — gamma-rays this time, as ultraviolet light would not be enough — at electrons, hoping to turn an electron into a muon. Using the notation

• for electron (the minus-sign reflecting its negative electric charge)
• for muon
• for a photon (and for a second photon)

we could try to look for the processes

• ,

possibly plus one or more photons, as shown in Figure 5.

Figure 5: If the electron is the ground state of an object and a muon is an excited state of the same object, then striking an electron with a high-energy photon ought to be able to turn it into a muon (possibly plus additional photons), in analogy to Figure 3.

Direct searches for processes like this have been done, and none has ever been seen. Even more significantly, if they were possible, then the following related process (shown in Figure 6) would also be possible

This has been searched for with great effort. Experiments show that no more than one in 2 trillion muons decay this way. The analogous processes for tau’s have never been seen, either.

Figure 6: The decay of a muon to an electron plus a photon has never been observed, despite considerable effort to do so. At best, it is exceedingly rare.

So what? Even though we can’t excite electrons this way, does that really prove that electrons can’t be excited in some other way?

Essentially, it does. The problem is that electrons are electrically charged, and so, if they are made from other, even more elementary objects, then one or more of these objects must also be electrically charged. By its very definition, “having non-zero electric charge” means “able to interact with photons.” It’s virtually impossible to imagine how an electrically charged interior would be unable to absorb photons. So this is an extremely strong mark against the idea.

But just to be sure, let’s try another approach.

Electron-Electron Collisions

We could also try aiming electrons at each other and seeing what happens when they collide. Just as atomic collisions cause atoms to be excited, we would expect that sufficiently powerful collisions would excite electrons to be muons and taus, and so we should observe processes similar to those in Fig. 4, such as

But again, none of these processes has ever been observed.

Electron-Positron Collisions

It’s interesting to compare this to what happens in collisions of electrons with the antiparticles of electrons, which are known as positrons and are denoted . In such collisions, we do regularly observe muons and taus appear, as follows

However, we never observe

or anything similar. Only a muon and an anti-muon, or a tau and an anti-tau, are ever created.

Meanwhile, another thing we observe

But clearly photons cannot be excited states of electrons, as photons have zero electric charge and smaller rest mass. So this process has nothing to do with creating an excited state.

Similarly, the processes that create and pairs have a simple interpretation that has nothing to do with electrons having internal structure and excited states. In the process , the electrons are not being kicked into excited states. Instead, the electron and positron are “annihilating” — they are transformed into a disturbance in the electromagnetic field (often called a “virtual photon” — but it is not a particle) — and this disturbance spontaneously transforms into two new particles that are “created” in their stead.

Each of the two new particles is an antiparticle of the other: the muon and the anti-muon , as particle types, are each other’s antiparticles, while photons are their own antiparticles. That’s why electron-positron collisions are just as likely to make photon pairs as to make or . Such annihilation/creation processes occur even for elementary particles, and so their presence gives no evidence supporting the idea of a muon as an excited electron.

We can consider other forms of scattering too, and in none of them do we ever see any of the processes that would be consistent with muons or taus being excited states of electrons. Moreover, all experiments on these particles agree with the math of the Standard Model of particle physics, which is based on the assumption that muons and taus are independent particles from electrons, and are not excited states of the latter.

We can conclude that this excited-electron hypothesis is completely dead. It has been for some decades.

What About Protons?

Protons, meanwhile, do have a size. Do the processes mentioned above work for them?

Yes. The first excited state of the proton is called the Delta ; the second is called the . The process

is observed. (In fact this process has a major role to play in the features of cosmic rays, where it causes what is known as the GZK cutoff.) [More easily observed is , which involves a virtual photon and therefore has a similar character.] Also observed is the decay

Scattering processes also create the excited states:

So we see, in experiments, many processes that we would expect to see if the proton is a composite object made of more elementary objects, for which the usual proton is the ground state and the and are excited states.

From these excited states, the size of a proton can be roughly inferred, as explained here.

What About All Those Photons?

But what about the fact that even electron-electron collisions often generate photons? Might that be an indication that electrons have excited states?

In other words, even in processes as simple as two electrons that scatter and remain electrons, photons generally appear

• etc.

Why aren’t these indications that electrons are composite? Because, as with the electron-positron annihilation processes discussed earlier, processes like these are expected even for elementary electrons; and predictions for those processes, based on the assumption that electrons are elementary, agree perfectly with data.

So does this mean that electrons definitely are elementary, point-like objects? Not definitely, no. It simply means that if electrons are the ground states of something complex (such as a string, as would potentially be true in string theory), the excited states of that object have far too much rest mass for us to produce them using today’s technology. Someday, collisions may produce them. But for now, all we can say is that in every experiment we can currently perform, electrons appear elementary. So do muons and taus; so do the neutrinos; and so do all six quarks of the Standard Model.

The strategy for tracking bird flu in US dairy cattle falls worryingly short of what is needed to prevent the outbreak from widening and potentially spreading to humans

At 5 a.m., the encampment was being taken down by the University of Chicago Police (I didn’t see anybody but University Police and Allied Security). Here is a short video of the action on the quad, with lots of chanting, police shouting, and cop-car lights flashing.

It doesn’t look as if anybody’s being arrested, but keffiyeh-clad and mask-clad protestors are fleeing the encampment. If they don’t take names or punish the encampers, they’ll just come back again. But I have no idea what information the University has.  The press, too, are being expelled from the Quad.

. . . and the Maroon’s report:

May 7, 5:09 a.m.

The raid came as most of the encampment had returned to their tents for the night. Two UCPD cars drove onto the quad and used their lamps to light up the encampment. Over a loudspeaker, UCUP ordered the demonstrators to leave the quad. Then, shortly after their announcements, several dozen officers in riot gear surrounded the encampment to prepare to enter.

— Peter Maheras, News Editor

May 7, 5:06 a.m.

The UCUP organizer said that they were not sure whether people were arrested. They believe that the goal was to push people out of the quad.

— Maroon Staff

May 7, 5:03 a.m.

A UCUP organizer described the raid in an interview with the Maroon.

“They pushed me. One person was on the ground. They’ve been pushing people out,” the organizer said.

“They did not give us a clear plan for leaving. They came in maybe two minutes after the warning. It’s clear that they waited until after the rally was over. We were at our most vulnerable,” the organizer added. “I believe we got everybody safely out of [their tents].”

— Maroon Staff

May 7, 4:59 a.m.

Police in riot gear are blocking access to the quad as many people arrive at the quad hoping to enter.

— Peter Maheras, News Editor; Emma Janssen, Deputy News Editor

An implantable heart pump could help children with heart failure awaiting transplants forego bulky devices that require long hospital stays

Skeptoid answers another round of listener feedback questions.

Perhaps if sheltered doctors cared more about health inequities, they wouldn't have treated a dangerous virus as nothing more than topic for an abstract, salon-style debate.

The post Dr. Jeffrey Flier: Those Who Express Different Views on Health Equity Should Be Demonized, Not Heard first appeared on Science-Based Medicine.

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At its simplest, Bayes’s theorem describes the probability of an event, based on prior knowledge of conditions that might be related to the event. But in Everything Is Predictable, Tom Chivers lays out how it affects every aspect of our lives. He explains why highly accurate screening tests can lead to false positives and how a failure to account for it in court has put innocent people in jail. A cornerstone of rational thought, many argue that Bayes’s theorem is a description of almost everything.

But who was the man who lent his name to this theorem? How did an 18th-century Presbyterian minister and amateur mathematician uncover a theorem that would affect fields as diverse as medicine, law, and artificial intelligence? Fusing biography and intellectual history, Everything Is Predictable is an entertaining tour of Bayes’s theorem and its impact on modern life, showing how a single compelling idea can have far reaching consequences.

Tom Chivers is an author and the award-winning science writer for Semafor. Previously he was the science editor at UnHerd.com and BuzzFeed UK. His writing has appeared in The Times (London), The Guardian, New Scientist, Wired, CNN, and more. He was awarded the Royal Statistical Society’s “Statistical Excellence in Journalism” awards in 2018 and 2020, and was declared the science writer of the year by the Association of British Science Writers in 2021. His books include The Rationalist’s Guide to the Galaxy: Superintelligent AI and the Geeks Who Are Trying to Save Humanity’s Future, and How to Read Numbers: A Guide to Stats in the News (and Knowing When to Trust Them). His new book is Everything Is Predictable: How Bayesian Statistics Explain Our World.

Shermer and Chivers discuss:

• Who was Thomas Bayes, what was his equation, and what problem did it solve?
• Bayesian decision theory vs. statistical decision theory
• Popperian falsification vs. Bayesian estimation
• Sagan’s ECREE principle
• Bayesian epistemology and family resemblance
• Paradox of the heap
• Bayesian brain
• Reality as controlled hallucination
• Bayesian prediction errors and why we can’t tickle ourselves
• Bayes and human irrationality
• Superforecasting
• Types of truth
• Mystical experiences and religious truths
• Replication Crisis in science
• Statistical Detection Theory and Signal Detection Theory
• Medical diagnosis problem and why most people get it wrong.

Show Notes
Medical Diagnosis Problem and Why Most People Get It Wrong

You go to the doctor not feeling well and they run some diagnostic tests, which indicate that you might have cancer. They tell you that this disease happens to 1 out of 100 people, or a 1% prevalence rate. The test sensitivity for this type of cancer is 90%, that is, the test will be right 90% of the time. The false positive rate of the test is 9%, that is, the test will be wrong 9% of the time. What is the percent likelihood that you have cancer?

When people are presented with this problem, the most common answer given is between 80% and 90%. The correct answer is 9%. This problem is so counterintuitive that not only do most people get it wrong, most medical professionals get it wrong. Think about that: a physician whom you trust runs some diagnostic tests and informs you that you have a 90% chance of having cancer when, in fact, it’s only 9%. That is a huge difference determining what decision you should make about treatment or not. What has gone wrong here? Let’s reframe the problem on a group of people tested for cancer and see how that cashes out on the diagnosis problem:

• In a sample size of 1,000 people, 10 have cancer (the base rate of 1%).
• Of these 10 people, 9 will test positive (the 90% sensitivity of the test).
• Of the 990 people without cancer, 89 will test positive (the 9% false-positive rate).
• A person tests positive. Does this person have cancer or not?

Here is how we compute the answer:

• Out of 1,000 people tested for cancer
• 98 of them test positive in all (9 + 89)
• 9 of them have cancer
• 9 divided by 98 = 0.091 or ~ 9%

Why do most people get such problems wrong in the original framing? The answer is threefold: (1) base rate neglect, that is, the rate of the phenomenon happening is ignored or discounted, in this case a low 1% base rate means the cancer is rare (in Bayesian language, the prior probability was low); (2) probabilities are counterintuitive, that is, they apply to populations of people, not to one person; (3) cognitive heuristics, that is, we’re not naturally Bayesian in our reasoning and instead we use cognitive shortcuts or rules of thumb. The Linda problem:

Linda is 31 years old, single, outspoken, and very bright. She majored in philosophy. As a student, she was deeply concerned with issues of discrimination and social justice, and also participated in anti-nuclear demonstrations.

Pinker on Blindness to Base Rates

Why can’t we predict who will attempt suicide? Why don’t we have an early-warning system for school shooters? Why can’t we profile terrorists or rampage shooters and detain them preventively? The answer comes out of Bayes’s rule: a less-than-perfect test for a rare trait will mainly turn out false positives. The heart of the problem is that only a tiny proportion of the population are thieves, suicides, terrorists, or rampage shooters (the base rate). Until the day that social scientists can predict misbehavior as accurately as astronomers predict eclipses, their best tests would mostly finger the innocent and harmless.

Bayesian Reasoning About UFOs

Leslie Kean’s 2010 book UFOs: Generals, Pilots and Government Officials Go on the Record, in which the UFOlogist admitted that “roughly 90 to 95 percent of UFO sightings can be explained” as:

…weather balloons, flares, sky lanterns, planes flying in formation, secret military aircraft, birds reflecting the sun, planes reflecting the sun, blimps, helicopters, the planets Venus or Mars, meteors or meteorites, space junk, satellites, swamp gas, spinning eddies, sundogs, ball lightning, ice crystals, reflected light off clouds, lights on the ground or lights reflected on a cockpit window, temperature inversions, hole-punch clouds, and the list goes on.

How The Light Gets In

At the 2023 HowTheLightGetsIn festival in London (sponsored by IAI, the Institute of Art and Ideas), during a panel discussion on the role of spiritual experience in our lives, in which I shared the stage with psychologist John Vervaeke and philosopher Sophie-Grace Chappell. Both quoted the noted philosopher Ludwig Wittgenstein at length, while I quoted Douglas Adams:

Isn’t it enough to see that a garden is beautiful without having to believe that there are fairies at the bottom of it too?

IAI News editor Ricky Williamson nevertheless makes my point:

This final argument from Shermer is a typical anti-spiritual retort. “Show us the evidence.” Well Michael, here it is: The mystical experience. The mystical experience, much like any other type of experience, offers clear evidence of spiritual reality. But what is the mystical experience?

The mystical experience is evidence of spiritual reality. Philosophical arguments for spirituality, or even for God, are of far less value in my estimation when compared to the empirical evidence of the mystical experience. Spiritual reality can be well-hidden when in a “normal” frame of mind, not much about regular reality hints at the presence of this possible, radical other, but when you see it, when you have a mystical experience, the experience is undeniable.

Feynman

If it disagrees with experiment, it’s wrong. In that simple statement is the key to science. It doesn’t make any difference how beautiful your guess is, how smart you are, who made the guess, or what his name is. If it disagrees with experiment, it’s wrong. That’s all there is to it.

Hume’s Maxim

The plain consequence is (and it is a general maxim worthy of our attention), “That no testimony is sufficient to establish a miracle, unless the testimony be of such a kind, that its falsehood would be more miraculous than the fact which it endeavours to establish.” When anyone tells me that he saw a dead man restored to life, I immediately consider with myself whether it be more probable, that this person should either deceive or be deceived, or that the fact, which he relates, should really have happened. I weigh the one miracle against the other; and according to the superiority, which I discover, I pronounce my decision, and always reject the greater miracle. If the falsehood of his testimony would be more miraculous than the event which he relates; then, and not till then, can he pretend to command my belief or opinion.

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Does another undetected planet languish in our Solar System’s distant reaches? Does it follow a distant orbit around the Sun in the murky realm of comets and other icy objects? For some researchers, the answer is “almost certainly.”

The case for Planet Nine (P9) goes back at least as far as 2016. In that year, astronomers Mike Brown and Konstantin Batygin published evidence pointing to its existence. Along with colleagues, they’ve published other work supporting P9 since then.

There’s lots of evidence for the existence of P9, but none of it has reached the threshold of definitive proof. The main evidence concerns the orbits of Extreme Trans-Neptunian Objects (ETNOs). They exhibit a peculiar clustering that indicates a massive object. P9 might be shepherding these objects along on their orbits.

This orbital diagram shows Planet Nine (lime green colour, labelled “P9”) and several extreme trans-Neptunian objects. Each background square is 100 AU across. Image Credit: By Tomruen – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=68955415

The names Brown and Batygin, both Caltech astronomers, come up often in regard to P9. Now, they’ve published another paper along with colleagues Alessandro Morbidelli and David Nesvorny, presenting more evidence supporting P9.

It’s titled “Generation of Low-Inclination, Neptune-Crossing TNOs by Planet Nine.” It’s published in The Astrophysical Journal Letters.

“The solar system’s distant reaches exhibit a wealth of anomalous dynamical structure, hinting at the presence of a yet-undetected, massive trans-Neptunian body—Planet Nine (P9),” the authors write. “Previous analyses have shown how orbital evolution induced by this object can explain the origins of a broad assortment of exotic orbits.”

To dig deeper into the issue, Batygin, Brown, Morbidelli, and Nesvorny examined Trans-Neptunian Objects (TNOs) with more conventional orbits. They carried out N-body simulations of these objects that included everything from the tug of giant planets and the Galactic Tide to passing stars.

29 objects in the Minor Planet Database have well-characterized orbits with a > 100 au, inclinations < 40°, and q (perihelia) < 30 au. Of those 29, 17 have well-quantified orbits. The researchers focused their simulations on these 17.

This figure from the research shows the 17 planets, their orbits, their perihelions, semi-major axes, and their inclinations. Image Credit: Batygin et al. 2024.

The researchers’ goal was to analyze these objects’ origins and determine if they could be used as a probe for P9. To accomplish this, they conducted two separate sets of simulations. One set with P9 in the Solar System and one set without.

The simulations began at t=300 million years, meaning 300 million years into the Solar System’s existence. At that time, “intrinsic dynamical evolution in the outer solar system is still in its infancy,” the authors explain, while enough time has passed for the Solar System’s birth cluster of stars to disperse and for the giant planets to have largely concluded their migrations. They ended up with about 2000 objects, or particles, in the simulation with perihelia greater than 30 au and semimajor axes between 100 and 5000 au. This ruled out all Neptune-crossing objects from the simulation’s starting conditions. “Importantly, this choice of initial conditions is inherently linked with the assumed orbit of P9,” they point out.

The figure below shows the evolution of some of the 2,000 objects in the simulations.

These panels show the evolution of selected particles within the calculations that attain nearly planar (i < 40°) Neptune-crossing orbits within the final 500 Myr of the integration. “Collectively, these examples indicate that P9-facilitated dynamics can naturally produce objects similar to those depicted in Figure 1” (the previous figure), the researchers explain. The top, middle, and bottom panels depict the time series of the semimajor axis, perihelion distance, and inclination, respectively. The rate of chaotic diffusion greatly increases when particles attain Neptune-crossing trajectories. Image Credit: Batygin et al. 2024.

These are interesting results, but the researchers point out that they in no way prove the existence of P9. These orbits could be generated by other things like the Galactic Tide. In their next step, they examined their perihelion distribution.

This figure from the research shows the perihelion distance for particles in a simulation with P9 (left) and without P9 (right.) The P9-free simulation shows a “rapid decline in perihelion distribution with decreasing q, as Neptune’s orbit forms a veritable dynamical barrier,” the researchers explain. Image Credit: Batygin et al. 2024.

“Accounting for observational biases, our results reveal that the orbital architecture of this group of objects aligns closely with the predictions of the P9-inclusive model,” the authors write. “In stark contrast, the P9-free scenario is statistically rejected at a ~5? confidence level.”

The authors point out that something other than P9 could be causing the orbital unruliness. The star was born in a cluster, and cluster dynamics could’ve set these objects on their unusual orbits before the cluster dispersed. A number of Earth-mass rogue planets could also be responsible, influencing the outer Solar System’s architecture for a few hundred million years before being removed somehow.

However, the authors chose their 17 TNOs for a reason. “Due to their low inclinations and perihelia, these objects experience rapid orbital chaos and have short dynamical lifetimes,” the authors write. That means that whatever is driving these objects into these orbits is ongoing and not a relic from the past.

An important result of this work is that it results in falsifiable predictions. And we may not have to wait long for the results to be tested. “Excitingly, the dynamics described here, along with all other lines of evidence for P9, will soon face a rigorous test with the operational commencement of the VRO (Vera Rubin Observatory),” the authors write.

A drone’s view of the Rubin Observatory under construction in 2023. The 8.4-meter is getting closer to completion and first light in 2025. The Observatory could provide answers to many outstanding issues, like the existence of Planet Nine. Image Credit: Rubin Observatory/NSF/AURA/A. Pizarro D

If P9 is real, what is it? It could be the core of a giant planet ejected during the Solar System’s early days. It could be a rogue planet that drifted through interstellar space until being caught up in our Solar System’s gravitational milieu. Or it could be a planet that formed on a distant orbit, and a passing star shepherded it into its eccentric orbit. If astronomers can confirm P9’s existence, the next question will be, ‘what is it?’

If you’re interested at all in how science operates, the case of P9 is very instructive. Eureka moments are few and far between in modern astronomy. Evidence mounts incrementally, accompanied by discussion and counterpoint. Objections are raised and inconsistencies pointed out, then methods are refined and thinking advances. What began as one over-arching question is broken down into smaller, more easily-answered ones.

But the big question dominates for now and likely will for a while longer: Is there a Planet Nine?

Stay tuned.

The post New Evidence for Our Solar System’s Ghost: Planet Nine appeared first on Universe Today.

Cybersecurity programs vary dramatically across the country, a review has found. The authors argue that program leaders should work with professional societies to make sure graduates are well trained to meet industry needs in a fast-changing field. A research team found a shortage of research in evaluating the instructional approaches being used to teach cybersecurity. The authors also contend that programs could benefit from increasing their use of educational and instructional tools and theories.

The Sun has been acting up; a certain sunspot has been producing powerful flares. In the past three days, several have reached or almost reached X-class, and one today was an X4.5 flare. (The letter is a measure of energy released by the flare; an X1 flare is ten times more powerful than an M1 class flare, and an X4.5 flare is almost three times more powerful than an X1 flare.)

From the https://www.swpc.noaa.gov/ website

With so much solar activity, it’s possible (though certainly not guaranteed) that one or more coronal mass ejections might strike Earth over the next 48 hours and might generate northern and southern lights (“auroras”). If you’re in a good location and the weather is favorable, you might want to check every now and then to see if the atmosphere is shining at you.

It’s that time again. NIAC (NASA Innovative Advanced Concepts) has announced six concepts that will receive funding and proceed to the second phase of development. This is always an interesting look at the technologies and missions that could come to fruition in the future.

The six chosen ones will each receive $600,000 in funding to pursue the ideas for the next two years. NASA expects each team to use the two years to address both technical and budgetary hurdles for their concepts. When this second phase comes to an end, some of the concepts could advance to the third stage.

“These diverse, science fiction-like concepts represent a fantastic class of Phase II studies,” said John Nelson, NIAC program executive at NASA Headquarters in Washington. “Our NIAC fellows never cease to amaze and inspire, and this class definitely gives NASA a lot to think about in terms of what’s possible in the future.”

Here they are.

Fluidic Telescope (FLUTE): Enabling the Next Generation of Large Space Observatories

Telescopes are built around mirrors and lenses, whether they’re ground-based or space-based. The JWST’s large mirror is 6.5 meters in diameter but had to be folded up to fit inside the rocket that launched it and then unfolded in space. That’s a tricky engineering feat. Engineers are building larger and larger ground-based telescopes, too, and they’re equally tricky to design and build. Could FLUTE change this?

FLUTE envisions lenses made of fluid, and the FLUTE team’s concept describes a space telescope with a primary mirror 50 meters (164 ft.) in diameter. Creating glass lenses for a telescope this large isn’t realistic. “Using current technologies, scaling up space telescopes to apertures larger than approximately 33 feet (10 meters) in diameter does not appear economically viable,” the FLUTE website states.

But in the microgravity of space, fluids behave in an intriguing way. Surface tension holds liquids together at their surfaces. We can see this on Earth, where some insects use surface tension to glide along the surfaces of ponds and other bodies of water. Also, on Earth, surface tension holds small drops of water together. But in space, away from Earth’s dominating gravity, surface tension is much more effective. There, water maintains the most energy efficient shape there is: a sphere.

Another force governs water: adhesion. Adhesion causes liquids to cling to surfaces. In the microgravity of space, adhesion can bind liquid to a circular, ring-like frame. Then, due to surface tension, the liquid will naturally adopt a spherical shape. If the liquid can be made to bulge inward rather than outward, and if the liquid is reflective enough, it creates a telescope mirror.

The FLUTE team would like to make optical components in space. The liquid would stay in the liquid state and form an extremely smooth light-collecting surface. As a bonus, FLUTE would also self-repair after any micrometeorite strike.

The FLUTE study is led by Edward Balaban from NASA’s Ames Research Center in California’s Silicon Valley. The FLUTE team has already done some tests on the ISS and on zero-g flights.

FLUTE researchers experience microgravity aboard Zero Gravity Corporation’s G-FORCE ONE aircraft while operating an experiment payload during a series of parabolic flights. Image Credits: Zero Gravity Corporation/Steve Boxall

Pulsed Plasma Rocket (PPR): Shielded, Fast Transits for Humans to Mars

It takes too long to get to Mars. It’s a six-month journey each way, plus time spent on the surface. All that time in microgravity, exposure to radiation, and other challenges make the trip very difficult for astronauts. PPR aims to fix that.

PPR isn’t a launch vehicle for escaping Earth’s gravity well. It would be launched on a heavy lift vehicle like SLS and then sent on its way.

PPR was originally derived from the Pulsed Fission Fusion concept. But it’s more affordable, and also smaller and simpler. PPR might generate 100,000 N of thrust with a specific impulse (Isp) of 5,000 seconds. Those are good numbers. PPR could reduce the travel time to Mars to two months.

It has other benefits as well. It could propel larger spacecraft to Mars on trips longer than two months, carrying more cargo and also provide heavier shielding against cosmic rays. “The PPR enables a whole new era in space exploration,” the team writes.

PPR is basically a fusion system ignited by fission. It’s similar to a thermonuclear weapon. But rather than a run-away explosion, the combined energy is directed through a magnetic nozzle to produce thrust.

In phase two, the PPR team intends to optimize the engine design to produce more specific impulse, perform proof-of-concept experiments for major components, and design a shielded ship for human missions to Mars.

This study is led by Brianna Clements with Howe Industries in Scottsdale, Arizona.

The Great Observatory for Long Wavelengths (GO-LoW)

One of modern astronomy’s last frontiers is the low-frequency radio sky. Earth’s ionosphere blocks our ground-based telescopes from seeing it. And space-based telescopes can’t see it either. It’s because the wavelengths are so long, in the meter to the kilometre scale. Only extremely massive telescopes could see these waves clearly.

GO-LoW is a potential solution. It’s a space-based array of thousands of identical Small-Sats arranged as an interferometer. It would sit at an Earth-Sun Lagrange point and observe exoplanet and stellar magnetic fields. Exoplanet magnetic fields emit radio waves between 100 kHz and 15 MHz. The GO-LoW team says their interferometer could perform the first survey of exoplanetary magnetic fields within 5 parsecs (16 light years.) Magnetic fields tell scientists a lot about an exoplanet, its evolution, and its processes.

GO-LoW is a Great Observatory concept to open the last unexplored window of the electromagnetic (EM) spectrum. The Earth’s ionosphere becomes opaque at approximately 10m wavelengths, so GO-LoW will join Great Observatories like HST and JWST in space to access this spectral window. Image Credits: NASA/GO-LoW

While there’s no doubt that large telescopes like the JWST are powerful and effective, they’re extremely complex and expensive. And if something goes wrong with a critical component, the mission could end.

GO-LoW takes a different approach. By using thousands of individual satellites, the system is more resilient. GO-LoW would have a hybrid constellation. Some of the satellites would be smaller and simpler satellites called “listener nodes” (LN,) while a smaller number of them would be “communication and computation” nodes (CCNs). They would collect data from the LNs, process it, and beam it back to Earth.

The GO-LoW says it would only take a few heavy launches to place an entire 100,000 satellite constellation in space.

The technology for the SmallSats already exists. The challenge the GO-LoW team will address with their phase two funding is developing a system that will harness everything together effectively. “The coordination of all these physical elements, data products, and communications systems is novel and challenging, especially at scale,” they write.

GO-LoW is led by Mary Knapp with MIT in Cambridge, Massachusetts.

Radioisotope Thermoradiative Cell Power Generator

It’s sort of like solar power in reverse.

The RTCPG is a power source for spacecraft visiting the outer planets. They promise smaller, more efficient power generation for smaller science and exploration missions that can’t carry a solar power system or nuclear power system. Both those systems are bulky, and solar power is limited the further away from the sun a spacecraft goes.

The thermoradiative cell (TRC) uses radioisotopes to create heat as an MMRTG does. But the TRC uses the heat to generate infrared light which generates electricity. In initial testing, the system generated 4.5 times more power from the same amount of PU-238.

Much of phase two’s work will involve materials. “Metal-semiconductor contacts capable of surviving the required elevated temperatures will be investigated,” the team explains. The team developed a special cryostat testing apparatus in phase one.

“Building on our results from Phase I, we believe there is much more potential to unlock here,” the team writes.

This power generation concept study is from Stephen Polly at the Rochester Institute of Technology in New York.

FLOAT: Flexible Levitation on a Track

What if Artemis is enormously successful? How will astronauts move their equipment around the lunar surface efficiently?

If the team behind FLOAT has their way, they’ll build the Moon’s first railway. Sort of. This artist’s concept shows a possible future mission depicting the lunar surface with planet Earth on the horizon. Image Credit: Ethan Schaler

FLOAT would provide autonomous transportation for payloads on the Moon. “A durable, long-life robotic transport system will be critical to the daily operations of a sustainable lunar base in the 2030’s,” the FLOAT team writes.

The heart of FLOAT is a three-layer flexible track that’s unrolled into position without major construction. It consists of three layers: a graphite layer, a flex-circuit layer, and a solar panel layer.

The graphite layer allows robots to use diamagnetic levitation to float over the track. The flex-circuit layer supplies the thrust that moves them, and the thin-film solar panel layer generates electricity for a lunar base when it’s in sunlight.

The system can be used to move regolith around for in-situ resource utilization and to transport payloads around a lunar base, for example, from landing zones to habitats.

“Individual FLOAT robots will be able to transport payloads of varying shape/size (>30 kg/m^2) at useful speeds (>0.5m/s), and a large-scale FLOAT system will be capable of moving up to 100,000s kg of regolith/payload multiple kilometres per day,” the FLOAT team explains.

With their phase two funding, the FLOAT team intends to design, build, and test scaled-down versions of FLOAT robots and track. Then, they’ll test their system in a lunar analog testbed. They’ll also test environmental effects on the system and how they alter the system’s performance and longevity.

Ethan Schaler leads FLOAT at NASA’s Jet Propulsion Laboratory in Southern California.

SCOPE: ScienceCraft for Outer Planet Exploration

Some of the most intriguing planets and moons in the Solar System are well beyond Jupiter. But exploring them is challenging. Extremely long travel times, restrictive mission windows, and large expenses limit our exploration. But SCOPE aims to address these limitations.

Typically, a spacecraft carries a propulsion and power system along with its instruments and communication systems. NASA’s Juno mission to Jupiter, for example, carries a chemical rocket engine for propulsion, 50 square meters of solar panels, and 10 science instruments. The solar panels alone weigh 340 kg (750 lbs.) Juno is powerful, produces a wide variety of quality science data, and is expensive.

ScienceCraft takes a different approach. It combines a single science instrument and spacecraft into one monolithic structure. It’s basically a solar sail with a built-in spectrometer. They’re aiming their design at the Neptune-Triton system.

This artist’s depiction shows ScienceCraft, which integrates the science instrument with the spacecraft by printing a quantum dot spectrometer directly on the solar sail to form a monolithic, lightweight structure.
Image Credit: Mahmooda Sultana

“By printing an ultra-lightweight quantum dot-based spectrometer, developed by the PI Sultana, directly on the solar sail, we create a breakthrough spacecraft architecture allowing an unprecedented parallelism and throughput of data collection and rapid travel across the solar system,” the ScienceCraft team writes.

Instead of merely providing the propulsion, the sail doubles as the spacecraft’s science instrument. The small mass means that ScienceCraft could be carried into orbit as a secondary payload. The team says they’ll use phase two to identify and develop key technologies for the spacecraft and to further mature the mission concept. They say that because of the low cost and simplicity, they could be ready by 2045.

“By leveraging these benefits, we propose a mission concept to Triton, a unique planetary body in our solar system, within the short window that closes around 2045 to answer compelling science questions about Triton’s atmosphere, ionosphere, plumes and internal structure,” the ScienceCraft team explains.

ScienceCraft is led by NASA’s Mahmooda Sultana at the agency’s Goddard Space Flight Center in Greenbelt, Maryland.

The post NASA Takes Six Advanced Tech Concepts to Phase II appeared first on Universe Today.

Engineers created a catapillar-shaped robot that splits into segments and reassembles, hauls cargo, and crawls through twisting courses.

Engineers created a catapillar-shaped robot that splits into segments and reassembles, hauls cargo, and crawls through twisting courses.

On Friday, May 3rd, the sixth mission in the Chinese Lunar Exploration Program (Chang’e-6) launched from the Wenchang Spacecraft Launch Site in southern China. Shortly after, China announced that the spacecraft separated successfully from its Long March 5 Y8 rocket. The mission, consisting of an orbiter and lander element, is now on its way to the Moon and will arrive there in a few weeks. By June, the lander element will touch down on the far side of the Moon, where it will gather about 2 kg (4.4 lbs) of rock and soil samples for return to Earth.

The mission launched four years after its predecessor, Chang’e-5, became China’s first sample-return mission to reach the Moon. It was also the first lunar sample return mission since the Soviet Luna 24 mission landed in Mare Crisium (the Sea of Crisis) in 1976. Compared to its predecessor, the Chang’e-6 mission weighs an additional 100 kg (220 lbs), making it the heaviest probe launched by the Chinese space program. The surface elements also face lesser-known terrain on the far side of the Moon and require a relay satellite for communications.

Speaking of surface elements, the China Academy of Space Technology (CAST) has since released images showing how the mission also carries a rover element. This payload was not part of mission data disclosed by China before the flight. But as SpaceNews’ Andrew Jones pointed out, the rover can be seen in the CAST images (see above) integrated onto the side of the lander.

Yeah, okay. That looks like a previously undisclosed mini rover on the side of the Chang'e-6 lander lol. Via CAST: https://t.co/gS0Jy5L9hw pic.twitter.com/9vvTnribpl

— Andrew Jones (@AJ_FI) May 3, 2024

“Little is known about the rover, but a mention of a Chang’e-6 rover is made in a post from the Shanghai Institute of Ceramics (SIC) under the Chinese Academy of Sciences (CAS),” he wrote. “It suggests the small vehicle carries an infrared imaging spectrometer.” This rover is no doubt intended to assist the lander with investigating resources on the far side of the Moon. This is consistent with China’s long-term plans for building the International Lunar Research Station (ILRS) around the southern polar region in collaboration with Roscosmos and other international patterns.

Similar to NASA’s plans for the Lunar Gateway and Artemis Base Camp, this requires that building sites be selected near sources of water ice and building materials (silica and other minerals). Ge Ping, the deputy director of the Center of Lunar Exploration and Space Engineering (CLESE) with the China National Space Administration (CNSA), related the importance of the sample-return mission to CGTN (a state-owned media company) before the launch:

“The Aitken Basin is one of the three major terrains on the Moon and has significant scientific value. Finding and collecting samples from different regions and ages of the Moon is crucial for our understanding of it. These would further study of the moon’s origin and its evolutionary history.”

In addition, the Chang’e-6 orbiter carries four international payloads and satellites including a French radon detector contributed by the ESA. Known as the Detection of Outgassing Radon (DORN), this payload will study how lunar dust and other volatiles (especially water) are transferred between the lunar regolith and the lunar exosphere. Then there’s the Italian INstrument for landing-Roving laser Retroreflector Investigations (INRRI), similar to those used by the Schiaparelli EDM module and InSight lander, that precisely measures distances from the lander to orbit.

The Chang’e-6 spacecraft stack shows a lunar rover attached to the mission lander. Credit: CAST

There’s also the Swedish Negative Ions on Lunar Surface (NILS), an instrument that will detect and measure negative ions reflected by the lunar surface. Lastly, there’s the Pakistani ICUBE-Q CubeSat developed by the Institute of Space Technology (IST) and Shanghai Jiao Tong University (SJTU), which will take images of the lunar surface using two optical cameras and measure the Moon’s magnetic field. The data these instruments provide will reveal new information about the lunar environment that will inform plans for long-duration missions on the surface.

By 2026, the Chang’e-6 mission will be joined by Chang’e-7, including an orbiter, lander, rover, and a mini-hopping probe. The data provided by the program will assist China’s plans to land taikonauts around the lunar south pole by 2030, followed by the completion of the ILRS by 2035.

Further Reading: CGTN

The post China is Going Back to the Moon Again With Chang'e-6 appeared first on Universe Today.

Earth is the only life-supporting planet we know of, so it’s tempting to use it as a standard in the search for life elsewhere. But the modern Earth can’t serve as a basis for evaluating exoplanets and their potential to support life. Earth’s atmosphere has changed radically over its 4.5 billion years.

A better way is to determine what biomarkers were present in Earth’s atmosphere at different stages in its evolution and judge other planets on that basis.

That’s what a group of researchers from the UK and the USA did. Their research is titled “The early Earth as an analogue for exoplanetary biogeochemistry,” and it appears in Reviews in Mineralogy. The lead author is Eva E. Stüeken, a PhD student at the School of Earth & Environmental Sciences, University of St Andrews, UK.

When Earth formed about 4.5 billion years ago, its atmosphere was nothing like it is today. At that time, the atmosphere and oceans were anoxic. About 2.4 billion years ago, free oxygen began to accumulate in the atmosphere during the Great Oxygenation Event, one of the defining periods in Earth’s history. But the oxygen came from life itself, meaning life was present when the Earth’s atmosphere was much different.

This isn’t the only example of how Earth’s atmosphere has changed over geological time. But it’s an instructive one and shows why searching for life means more than just searching for an atmosphere like modern Earth’s. If that’s the way we conducted the search, we’d miss worlds where photosynthesis hadn’t yet appeared.

In their research, the authors point out how Earth hosted a rich and evolving population of microbes under different atmospheric conditions for billions of years.

“For most of this time, Earth has been inhabited by a purely microbial biosphere albeit with seemingly increasing complexity over time,” the authors write. “A rich record of this geobiological evolution over most of Earth’s history thus provides insights into the remote detectability of microbial life under a variety of planetary conditions.”

It’s not just life that’s changed over time. Plate tectonics have changed and may have been ‘stagnant lid’ tectonics for a long time. In stagnant lid tectonics, plates don’t move horizontally. That can have consequences for atmospheric chemistry.

The main point is that Earth’s atmosphere does not reflect the solar nebula the planet formed in. Multiple intertwined processes have changed the atmosphere over time. The search for life involves not only a better understanding of these processes, but how to identify what stage exoplanets might be in.

This figure from the research shows how the abundance of major gases in Earth’s atmosphere has changed over time due to various factors. Image Credit: Stüeken et al. 2024.

It’s axiomatic that biological processes can have a dramatic effect on planetary atmospheres. “On the modern Earth, the atmospheric composition is very strongly controlled by life,” the researchers write. “However, any potential atmospheric biosignature must be disentangled from a backdrop of abiotic (geological and astrophysical) processes that also contribute to planetary atmospheres and would be dominating on lifeless worlds and on planets with a very small biosphere.”

The authors outline what they say are the most important lessons that the early Earth can teach us about the search for life.

The first is that the Earth has actually had three different atmospheres throughout its long history. The first one came from the solar nebula and was lost soon after the planet formed. That’s the primary atmosphere. The second one formed from outgassing from the planet’s interior. The third one, Earth’s modern atmosphere, is complex. It’s a balancing act involving life, plate tectonics, volcanism, and even atmospheric escape. A better understanding of how Earth’s atmosphere has changed over time gives researchers a better understanding of what they see in exoplanet atmospheres.

Earth’s Hadean Eon is a bit of a mystery to us because geologic evidence from that time is scarce. During the Hadean, Earth had its primary atmosphere from the solar nebula. But it soon lost it and accumulated another one via outgassing as the planet cooled. Credit: NASA

The second is that the further we look back in time, the more the rock record of Earth’s early life is altered or destroyed. Our best evidence suggests life was present by 3.5 billion years ago, maybe even by 3.7 billion years ago. If that’s the case, the first life may have existed on a world covered in oceans, with no continental land masses and only volcanic islands. If there had been abundant volcanic and geological activity between 3.5 and 3.7 billion years ago, there would’ve been large fluxes of CO2 and H2. Since these are substrates for methanogenesis, then methane may have been abundant in the atmosphere and detectable.

The third lesson the authors outline is that a planet can host oxygen-producing life for a long time before oxygen can be detected in an atmosphere. Scientists think that oxygenic photosynthesis appeared on Earth in the mid-Archean eon. The Archean spanned from 4 billion to 2.5 billion years ago, so mid-Archean is sometime around 3.25 billion years ago. But oxygen couldn’t accumulate in the atmosphere until the Great Oxygenation Event about 2.4 billion years ago. Oxygen is a powerful biomarker, and if we find it in an exoplanet’s atmosphere, it would be cause for excitement. But life on Earth was around for a long time before atmospheric oxygen would’ve been detectable.

Earth’s history is written in chemical reactions. This figure from the research shows the percentage of sulphur isotope fractionation in sediments. The sulphur signature disappeared after the GOE because the oxygen in the atmosphere formed an ozone shield. That blocked UV radiation, which stopped sulphur dioxide photolysis. “Anoxic planets where O2 production never occurs are more likely to resemble the early Earth prior to the GOE,” the authors explain. Image Credit: Stüeken et al. 2024.

The fourth lesson involves the appearance of horizontal plate tectonics and its effect on chemistry. “From the GOE onwards, the Earth looked tectonically similar to today,” the authors write. The oceans were likely stratified into an anoxic layer and an oxygenated surface layer. However, hydrothermal activity constantly introduced ferrous iron into the oceans. That increased the sulphate levels in the seawater which reduced the methane in the atmosphere. Without that methane, Earth’s biosphere would’ve been much less detectable. Complicated, huh?

“Planet Earth has evolved over the past 4.5 billion years from an entirely anoxic planet
with possibly a different tectonic regime to the oxygenated world with horizontal plate
tectonics that we know today,” the authors explain. All that complex evolution allowed life to appear and to thrive, but it also makes detecting earlier biospheres on exoplanets more complicated.

We’re at a huge disadvantage in the search for life on exoplanets. We can literally dig into Earth’s ancient rock to try to untangle the long history of life on Earth and how the atmosphere evolved over billions of years. When it comes to exoplanets, all we have is telescopes. Increasingly powerful telescopes, but telescopes nonetheless. While we are beginning to explore our own Solar System, especially Mars and the tantalizing ocean moons orbiting the gas giants, other solar systems are beyond our physical reach.

“We must instead remotely recognize the presence of alien biospheres and characterize their biogeochemical cycles in planetary spectra obtained with large ground- and space-based telescopes,” the authors write. “These telescopes can probe atmospheric composition by detecting absorption features associated with specific gases.” Probing atmospheric gases is our most powerful approach right now, as the JWST shows.

The JWST has made headlines for examining exoplanet atmospheres and identifying chemicals. A transmission spectrum of the hot gas giant exoplanet WASP-39 b, captured by Webb’s Near-Infrared Spectrograph (NIRSpec) on July 10, 2022, revealed the first definitive evidence for carbon dioxide in the atmosphere of a planet outside the Solar System. Credit: NASA, ESA, CSA, and L. Hustak (STScI). Science: The JWST Transiting Exoplanet Community Early Release Science Team

But as scientists get better tools, they’ll start to go beyond atmospheric chemistry. “We might also be able to recognize global-scale surface features, including light interaction with photosynthetic pigments and ‘glint’ arising from specular reflection of light by a liquid ocean.”

Understanding what we’re seeing in exoplanet atmospheres parallels our understanding of Earth’s long history. Earth could be the key to our broadening and accelerating search for life.

“Unravelling the details of Earth’s complex biogeochemical history and its relationship with remotely observable spectral signals is an important consideration for instrument design and our own search for life in the Universe,” the authors write.

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