Science

In the summer of 2022, the journal Nature Human Behavior put out a notice that it could reject articles that were “stigmatizing” or “harmful” to different groups, regardless of the scientific content. The problems with this stand, which were immediately called out by Steve Pinker, Michael Shermer, and others, is that what is seen as stigmatizing or harmful is pretty much a subjective matter, and, as Pinker tweeted:

I think the journal and its editor were taken aback by this and similar reactions to their statements, and on Day 2 of our USC conference on Science and Ideology in January, the Chief Editor of the journal, Stavroula Kousta, walked back their statement a bit in here 24-minute talk (go here to here her talk; it’s the first one on the video).

But the walking-back didn’t mean that Nature Human Behavior was becoming less woke. Indeed, it just published a ridiculously repetitive and trite paper about how science needs “allyship” to produce a “diverse, equitable, and inclusive academia.” It’s not that STEM isn’t seeking a diversity of groups and viewpoints—though, inevitably, “diversity” in their sense means “diversity of race or sex”—but that this article says absolutely nothing new about the issue. What the journal published now is a prime example of virtue-flaunting that, in the end accomplish nothing.  You can read it by clicking on the screenshot below (it should be free with the legal Unpaywall app), and you can get the pdf here.

The piece begins with the usual claim of “harm”: the same issue that the same journal discussed before:

In academia, despite recent progress towards diversity, biases and microaggressions can still exclude and harm members of disadvantaged social groups.

The person who sent me this article wrote “No citations are given for this claim about bigotry and discrimination at the most liberal, open, welcoming institutions that have ever existed in human history. Amazing.”

The article then gives these figures, which are baffling because one would expect younger women to drop out more rather than less frequently. But they may be correct; I am just not sure that they reflect misogyny:

Such patterns of marginalization are not specific to students. Among US faculty members, for example, women are 6%, 10% and 19% more likely to leave each year than their men counterparts as assistant, associate and full professors, respectively.

I suspect that these departures have little to do with ongoing “structural bias” against women academics, not only because no instances of inbuilt structural bias are actually given, but also, at least for women, a big and recent review by Ceci et al. found either no bias against women’s achievements in academic science or a female advantage—save for teaching evaluations and a slight difference in salary, about 3.6% lower salary for women.   However, the authors do not dismiss the possibility and importance of bias against women.

At any rate, if you haven’t heard come across this advice about “allyship” before, and are an academic, you must be blind and deaf. I’m not going to reprise the paper for you, as you’ve heard it all before.

I’m assuming that well-meaning people agree with me that marginalized scientists should be treated just like everyone else.  But how many times do we need to hear that? At any rate, this paper rings the chimes again, singling out six areas where we’re told how to behave. These are direct quotes.

1.) Listen to and centre marginalized voices.

2.) Reflect on and challenge your own biases (I guess you determine them by taking an “implicit bias” test, a procedure that’s been severely criticized

3.)  Speak up to include and support disadvantaged groups

4.)  Speak out against bias when it happens

5.)  Advocate for institutional initiatives to promote equity and inclusion

6.)  Dismantle institutional policies and procedures of exclusion

#4 and #6 are no-brainers, though, speaking personally, I don’t know of any institutional policies and procedures of exclusion in biology.  The rest are ideological statements assuming that everyone except for the marginalized is biased, and that the way to achieve inclusion is to promote “equity” (do they even know what “equity” means?) And, of course, the entire program reflects the tenets of DEI, which are on the chopping block in the U.S.

Now this article isn’t as bad as ones on feminist glaciology or ones maintaining that Einstein’s principle of covariance supports the view that minorities have an equal claim to objectivity..  No, it’s just superfluous, a farrago of what decent human beings already do, misleading assertions about bias, mixed with patronizing advice that we already follow. It accomplishes nothing save further erode the credibility of editor Kousta.

Here’s the conclusion:

For allyship to be effective in academia, it must be grounded in a deep commitment to DEI. This means recognizing that allyship is not a one-time event, but an ongoing process of learning, reflection and action. Moreover, it needs to go above and beyond symbolic or superficial acts (performative allyship) to demonstrate substantial and meaningful support that is recognized as beneficial by those it is meant to serve (substantive allyship). It is noteworthy to understand and accept that we will make mistakes along the way. No one is perfect, and as explained above, allyship requires a willingness to engage in humility and self-reflection. When mistakes are made, it is important to listen to feedback from disadvantaged groups, take responsibility for any harm caused, and commit to doing better in the future.

In conclusion, everyone can engage in allyship and work to challenge and dismantle systemic bias, creating a more just, equitable and inclusive academic community for all.

At least they used “equitable” properly, meaning “treating people fairly.”  But couldn’t the whole article have consisted of just that sentence?

Preserved wooden spears from hundreds of thousands of years ago seem to have been suitable for throwing, not just close-range attacks

The site of a deep-sea mining test in 1979 had lower levels of biodiversity when researchers revisited it in 2023 compared with undisturbed areas nearby

From the perspective of complex systems, the study reveals the universality, specificity, and explanatory power of underlying rules governing urban system evolution.

Scientists have developed an AI-powered tool that detects 64% of brain abnormalities linked to epilepsy that human radiologists miss.

Trigger(nometry) warning: semi-conservative video.

I can’t remember who recommended I watch this video, which features satirist, author, and Triggernometry co-host Konstantin Kisin speaking for 15 minutes at a meeting of the Alliance for Responsible Citizenship (ARC). The group is described by Wikipedia as “an international organisation whose aim is to unite conservative voices and propose policy based on traditional Western values.”

The talk is laced with humor, but the message is serious:  Kisin argues that societies based on “Western values” are the most attractive, as shown by the number of potential immigrants; but they are endangered by the negativity and “lies” of those who tell us that “our history is all bad and our country is plagued by prejudice and intolerance.” To that he replies that people espousing such sentiments still prefer to live in the West. (But of course that doesn’t mean that these factors still aren’t at play in the West!)  Kisin then touts both Elon Musk (for “building big things”) and (oy) Jordan Peterson for “reminding us that our lives will improve if we accept that “honesty is better than lies, that responsibility is better than blame, and strength is better than weakness.”

He continues characterizing the West as special: “the most free and prosperous societies in the history of humanity, and we are going to keep them that way.” To accomplish that, he promotes free speech as the highest of Western values, and rejects identity politics, arguing that “multiethnic societies can work; multicultural societies cannot.” Finally, he claims that human beings are good, denying (as he avers) the woke view that “human beings are a pestilence on the planet.”  Kisin calls for more reproduction and making energy “as cheap and abundant as possible.”

The talk finishes with the most inspiring thing Kising says he’s ever heard: that we’re going to die; ergo, we have nothing to lose. “We might as well speak the truth, we might as well reach for the stars, we might as well fight like our lives depended on it—because they do.”  I’m not exactly sure what he means, nor do I feel uplifted or inspired by these words, which don’t really tell us why he thinks the tide is turning. And, at the end, I could see where this optimistic word salad came from: it’s in Wikipedia, too:

[The ARC] is associated with psychologist and political commentator Jordan Peterson. One Australian journalist identified the purpose of ARC as follows: “to replace a sense of division and drift within conservatism, and Western society at large, with a renewed cohesion and purpose”.

Do any readers get inspired by this kind of chest-pounding?  I have to add that I do like Triggernometry, one of the few podcasts I can listen to, but I’m not especially energized by the co-host’s speech.

Type-1 diabetes, IBD, multiple sclerosis, rheumatoid arthritis, coeliac disease and lupus are all caused by the body attacking itself. But new therapies that reset the immune system could offer lasting help

A SpaceX Falcon 9 rocket is about to launch a number of missions, including a private lunar lander, a lunar satellite for NASA and a prospecting probe for an asteroid-mining company

If you’re following this site, you’ll know that 22 biologists (including me) sent a letter to three ecology and evolution societies who had issued a statement directed at the President and Congress that biological sex was a spectrum and a continuum in all species. The statement claimed without support that it expressed a consensus view of biologists, although the members of the societies were not polled.

Of course this behavior could not stand, and so Luana Maroja cobbled together a letter to those societies noting that the biological definition of sex was based on the development of the apparatus evolved to produce gametes, and that this showed that all animals and plants had only two sexes: male and female. As Richard Dawkins pointed out, even the three Society Presidents used the sex binary in their own biological work.

The letter has now accumulated more than a hundred signatures.  If you are an anisogamite and want to sign the letter, this is a reminder that the deadline for signatures is in about a week: 5 p.m. Monday, March 3. You can sign it this way (from Luana’s post on Heterodox STEM);

The societies for the Study of Evolution (SSE), the American Society of Naturalists (ASN) and the Society for Systematic Biologists (SSB) issued a declaration addressed to President Trump and all the members of Congress (declaration also archived here), proffering a confusing definition of sex, implying that sex is not binary.

We wrote a short letter explaining that sex is indeed defined by gamete type.

We are now collecting more signatures from biologists who agree to have their name publicly posted. If you are a biologist (or in a field related to biology) want to add your name, just fill in the bottom of this form (it contains the full text of our letter and a link to the tri-societies’ letter).

Please fill in all the blanks, including your name, position, and email, and we ask that you have something to do with biology. Also, we will most likely post the letter with names, so if you want to remain publicly anonymous but agree with our sentiments, just write your own personal email to the Society presidents (two of them have emails in the original letter). Nobody’s email will become public if I decide to post the final letter and signers on this site.

It takes about one minute to fill in the form, so if you want to send a message to these three societies, you know what to do.

We have contributions from two people, but I am holding onto those, as it appears that this feature will become sporadic in the future. That’s sad, no?

Venus differs from Earth in many ways including a lack of internal dynamo driving global magnetosphere to shield potential life from solar and cosmic radiation. However, Venus possesses a dense atmosphere and, in a recent study, planetary scientists conducted simulations of the Venusian atmosphere to determine radiation penetration to the lower cloud layers. Their calculations revealed that the atmospheric thickness provides adequate protection for life at what’s considered Venus’s “habitable zone,” located 40–60 km above the surface.

Venus, the second planet from the Sun, is often called Earth’s “sister planet” because of its comparable size and composition. Yet its environment couldn’t be more different or extreme. It has a thick carbon dioxide atmosphere with sulfuric acid clouds that have created a runaway greenhouse effect, making Venus the solar system’s hottest planet—surface temperatures in excess of 475°C. The Venusian landscape features volcanic plains, mountains, and canyons under atmospheric pressure exceeding 90 times Earth’s. Despite these inhospitable conditions, Venus remains an object of scientific interest, with researchers studying its geology and atmosphere.

Venus

In 2020, scientists found phosphine in Venus’s atmosphere which, on Earth, is mostly made by biological processes or in other words – living things. This discovery was somewhat unexpected and facilitated a fresh look at Venus as a possible home for life. Surprisingly perhaps, Venus does have a “habitable zone” in its clouds about 40-60 km up, where the temperature and pressure aren’t too different from Earth’s. While the planet’s surface is totally uninhabitable, high up in the atmosphere might actually support some kind of microbial life that’s adapted to acidic conditions. A new piece of research has been exploring if the thick Venusian atmosphere would protect any such life that may have evolved or whether intense radiation bathes its habitable zone. 

The spectral data from SOFIA overlain atop this image of Venus from NASA’s Mariner 10 spacecraft is what the researchers observed in their study, showing the intensity of light from Venus at different wavelengths. If a significant amount of phosphine were present in Venus’s atmosphere, there would be dips in the graph at the four locations labeled “PH3,” similar to but less pronounced than those seen on the two ends. Credit: Venus: NASA/JPL-Caltech; Spectra: Cordiner et al.

The research, that was led by Luis A. Anchordoqui from the University of New York has revealed surprising results. The team discovered that despite Venus lacking a magnetic field and orbiting closer to the Sun, the radiation levels in its potentially habitable cloud layer are remarkably similar to those at Earth’s surface. Using the AIRES simulation package (AIRshower Extended Simulations – simulates cascades of secondary particles from incoming high energy radiation) the team generated over a billion simulated cosmic ray showers to analyse particle interactions within Venus’s atmosphere. 

Their findings show that at equivalent atmospheric depths, particle fluxes on Venus and Earth are nearly identical, with only about 40% higher radiation detected at the uppermost boundary of Venus’s habitable zone. This suggests Venus’s thick atmosphere provides substantial radiation shielding that might be sufficient for potential microbial life.

The research suggests that cosmic radiation wouldn’t significantly hinder life in Venus’s cloud layer. Any potential microorganisms that were there would face radiation levels similar to those on Earth’s surface. On Earth, life has found a way across a wide range of environments that span many kilometres, this is known as its life reservoir. Venus doesn’t have such a great reservoir so if radiation were to sterilise the habitable clouds, there’s no equivalent to Earth’s subsurface biosphere that could eventually recolonise the region. This means life needs to persist continuously in its atmospheric habitat without being able to move to other parts of the planet.

Source : The Venusian Chronicles

The post Although it Lacks a Magnetic Field, Venus Can Still Protect With in its Atmosphere appeared first on Universe Today.

Why do I find the word particle so problematic that I keep harping on it, to the point that some may reasonably view me as obsessed with the issue? It has to do with the profound difference between the way an electron is viewed in 1920s quantum physics (“Quantum Mechanics”, or QM for short) as opposed to 1950s relativistic Quantum Field Theory (abbreviated as QFT). [The word “relativistic” means “incorporating Einstein’s special theory of relativity of 1905”.] My goal this week is to explain carefully this difference.

The overarching point:

• in QM, an electron really is a particle, at least to the limited extent that QM can handle that notion;
• in QFT, an electron is at best a “particle”, with the word in quotation marks
  • (and I personally prefer the term wavicle.)

I’ve discussed this to some degree already in my article about how the view of an electron has changed over time, but here I’m going to give you a fuller picture. To complete the story will take two or three posts, but today’s post will already convey one of the most important points.

There are two short readings that you may want to dofirst.

• The first is an article about the distinction between physical space (within which all objects actually are located) and the abstract space of possibilities (which consists of all ways that the objects in a physical system could be arranged in physical space.) This issue, essential in quantum physics of any type, will be crucial below.
• The second is a short section of a blog post that explains how QM views an isolated object in a state of definite momentum — i.e. something whose motion (both speed and direction) is precisely known, and whose position is therefore completely unknown, thanks to Heisenberg’s uncertainty principle.

I’ll will review the main point of the second item, and then I’ll start explaining what an isolated object of definite momentum looks like in QFT.

Removing Everything Extraneous

First, though, let’s make things as simple as possible. Though electrons are familiar, they are more complicated than some of their cousins, thanks to their electric charge and “spin”, and the fact that they are fermions. By contrast, bosons with neither charge nor spin are much simpler. In nature, these include Higgs bosons and electrically-neutral pions, but each of these has some unnecessary baggage. For this reason I’ll frame my discussion in terms of imaginary objects even simpler than a Higgs boson. I’ll call these spinless, chargeless objects “Bohrons” in honor of Niels Bohr (and I’ll leave the many puns to my readers.)

For today we’ll just need one, lonely Bohron, not interacting with anything else, and moving along a line. Using 1920s QM in the style of Schrödinger, we’ll take the following viewpoints.

• A Bohron is a particle and exists in physical space, which we’ll take to be just a line — the set of points arranged along what we’ll call the x-axis.
• The Bohron has a property we call position in physical space. We’ll refer to its position as x1.
• For just one Bohron, the space of possibilities is simply all of its possible positions — all possible values of x1. [See Fig. 1]
• The system of one isolated Bohron has a wave function Ψ(x1), a complex number at each point in the space of possibilities. [Note it is not a function of x, the points in physical space; it is a function of x1, the possible positions of the Bohron.]
• The wave function predicts the probability of finding the Bohron at any selected position x1: it is proportional to |Ψ(x1)|2, the square of the absolute value of the complex number Ψ(x1).

Figure 1: For a Bohron moving along a line, physical space is the x-axis where the Bohron (blue dot) is located. The space of possibilities, the set of all possible arrangements of our one-Bohron system (red star) is the the x1-axis. This subtle but important distinction becomes clearer when we have two or more Bohrons; the physical space is unchanged, but possibility space is totally different. A QM State of Definite Momentum

In a previous post, I described states of definite momentum. But I also described states whose momentum is slightly less definite — a broad Gaussian wave packet state, which is a bit more intutive. The wave function for a Bohron in this state is shown in Fig. 2, using three different representations. You can see intuitively that the Bohron’s motion is quite steady, reflecting near definite momentum, while the wave function’s peak is very broad, reflecting great uncertainty in the Bohron’s position.

• Fig. 2a shows the real and imaginary parts of Ψ(x1) in red and blue, along with its absolute-value squared |Ψ(x1)|2 in black.
• Fig. 2b shows the absolute value |Ψ(x1)| in a color that reflects the argument [i.e. the phase] of Ψ(x1).
• Fig. 2c indicates |Ψ(x1)|2, using grayscale, at a grid of x1 values; the Bohron is more likely to be found at or near dark points than at or near lighter ones.

For more details and examples using these representations, see this post.

Figure 2a: The wave function for a wave packet state with near-definite momentum, showing its real (red) and imaginary (blue) parts and its absolute value squared (black.) Figure 2b: The same wave function, with the curve showing its absolute value and colored by its argument. Figure 2c: The same wave function, showing its absolute value squared using gray-scale values on a grid of x1 points. The Bohron is more likely to be found near dark-shaded points.

To get a Bohron of definite momentum P1, we simply take what is plotted in Fig. 2 and make the broad peak wider and wider, so that the uncertainty in the Bohron’s position becomes infinite. Then (as discussed in this post) the wave function for that state, referred to as |P1>, can be drawn as in Fig. 3:

Figure 3a: As in Fig. 2a, but now for a state |P1> of precisely known momentum to the left. Figure 3b: As in Fig. 2b, but now for a state |P1> of precisely known momentum to the left. Figure 3c: As in Fig. 2c, but now for a state |P1> of precisely known momentum; note the probability of finding the Bohron is equal at every point at all times.

In math, the wave function for the state at some fixed moment in time takes a simple form, such as

where i is the square root of -1. This is a special state, because the absolute-value-squared of this function is just 1 for every value of x1, and so the probability of measuring the Bohron to be at any particular x1 is the same everywhere and at all times. This is seen in Fig. 3c, and reflects the fact that in a state with exactly known momentum, the uncertainty on the Bohron’s position is infinite.

Let’s compare the Bohron (the particle itself) in the state |P1> to the wave function that describes it.

• In the state |P1>, the Bohron’s location is completely unknown. Still, its position is a meaningful concept, in the sense that we could measure it. We can’t predict the outcome of that measurement, but the measurement will give us a definite answer, not a vague indefinite one. That’s because the Bohron is a particle; it is not spread out across physical space, even though we don’t know where it is.
• By contrast, the wave function Ψ(x1) is spread out, as is clear in Fig. 3. But caution: it is not spread out across physical space, the points of the x axis. It is spread out across the space of possibilities — across the range of possible positions x1. See Fig. 1 [and read my article on the space of possibilities if this makes no sense to you.]
• Thus neither the Bohron nor its wave function is spread out in physical space!

We do have waves here, and they have a wavelength; that’s the distance between one crest and the next in Fig. 3a, and the distance beween one red band and the next in Fig. 3b. That wavelength is a property of the wave function, not a property of the Bohron. To have a wavelength, an object has to be wave-like, which our QM Bohron is not.

Conversely, the Bohron has a momentum (which is definite in this state, and is something we can measure). This has real effects; if the Bohron hits another particle, some or all of its momentum will be transferred, and the second particle will recoil from the blow. By contrast, the wave function does not have momentum. It cannot hit anything and make it recoil, because, like any wave function, it sits outside the physical system. It merely describes an object with momentum, and tells us the probable outcomes of measurements of that object.

Keep these details of wavelength (the wave function’s purview) and the momentum (the Bohron’s purview) in mind. This is how 1920’s QM organizes things. But in QFT, things are different.

First Step Toward a QFT State of Definite Momentum

Now let’s move to quantum field theory, and start the process of making a Bohron of definite momentum. We’ll take some initial steps today, and finish up in the next post.

Our Bohron is now a “particle”, in quotation marks. Why? Because our Bohron is no longer a dot, with a measurable (even if unknown) position. It is now a ripple in a field, which we’ll call the Bohron field. That said, there’s still something particle-like about the Bohron, because you can only have an integer number (1, 2, 3, 4, 5, …) of Bohrons, and you can never have a fractional number (1/2, 7/10, 2.46, etc.) of Bohrons. This feature is something we’ll discuss in later posts, but we’ll just accept it for now.

As fields go, the Bohron field is a very simple example. At any given moment, the field takes on a value — a real number — at each point in space. Said another way, it is a function of physical space, of the form B(x).

Very, very important: Do not confuse the Bohron field B(x) with a wave function!!

• This field is a function in physical space (not the space of possibilities). B(x) is a function of physical space points x that make up the x-axis, and is not a function of a particle’s position x1, nor is it a function of any other coordinate that might arise in the space of possibilities.
• I’ve chosen the simplest type of QFT field: B(x) is a real number at each location in physical space. This is in contrast to a QM wave function, which is a complex number for each possibility in the space of possibilities.
• The field itself can carry energy and momentum and transport it from place to place. This is unlike a wave function, which can only describe the energy and momentum that may be carried by physical objects.

Now here’s the key distinction. Whereas the Bohron of QM has a position, the Bohron of QFT does not generally have a position. Instead, it has a shape.

If our Bohron is to have a definite momentum P1, the field must ripple in a simple way, taking on a shape proportional to a sine or cosine function from pre-university math. An example would be:

where A is a real number, called the “amplitude” of the wave, and x is a location in physical space.

At some point soon we’ll consider all possible values of A — a part of the space of possibilities for the field B(x) — so remember that A can vary. To remind you, I’ve plotted this shape for A=1 in Fig. 4a and again for A=-3/2 in Fig 4b.

Figure 4a: The function A cos[P1 x], for the momentum P1 set equal to 1 and the amplitude A set equal to 1. Figure 4b: Same as Fig. 4a, but with A = -3/2 . Initial Comparison of QM and QFT

At first, the plots in Fig. 4 of the QFT Bohron’s shape look very similar to the QM wave function of the Bohron particles, especially as drawn in Fig. 3a. The math formulas for the two look similar, too; compare the formula after Fig. 3 to the one above Fig. 4.

However, appearances are deceiving. In fact, when we look carefully, EVERYTHING IS COMPLETELY DIFFERENT.

• Our QM Bohron with definite momentum has a wave function Ψ(x1), while in QFT it has a shape B(x); they are functions of variables which, though related, are different.
  
  
• On top of that, there’s a wave function in QFT too, which we haven’t drawn yet. When we do, we’ll see that the QFT Bohron’s wave function looks nothing like the QM Bohron’s wave function. That’s because
  • the space of possibilities for the QM wave function is the space of possible positions that the Bohron particle can have, but
  • the space of possibilities for the QFT wave function is the space of all possible shapes that the Bohron field can have.
• The plot in Fig. 4 shows a curve that is both positive and negative but is drawn colorless, in contrast to Fig. 3b, where the curve is positive but colored. That’s because
  • the Bohron field B(x) is a real number with no argument [phase], whereas
  • the QM wave function Ψ(x1) for the state of definite momentum has an always-positive absolute value and a rapidly varying argument [phase].
• The axes in Fig. 4 are labeled differently from the axis in Fig. 3. That’s because (see Fig. 1)
  • the QFT Bohron field B(x) is found in physical space, while
  • the QM wave function Ψ(x1) for the Bohron particle is found in the particle’s space of possibilities.
• The absolute-value-squared of a wave function |Ψ(x1)|2 is interpreted as a probability (specifically, the probability for the particular possibility that the particle is at position x1. There is no such interpretation for the square of the Bohron field |B(x)|2. We will later find a probability interpretation for the QFT wave function, but we are not there yet.
  
  
• Both Fig. 4 and Figs. 3a, 3b show curves with a wavelength, albeit along different axes. But they are very different in every sense
  • In QM, the Bohron has no wavelength; only its wave function has a wavelength — and that involves lengths not in physical space but in the space of possibilities.
  • In QFT,
    • the field ripple corresponding to the QFT Bohron with definite momentum has a physical wavelength;
    • meanwhile the QFT Bohron’s wave function does not have anything resembling a wavelength! The field’s space of possibilities, where the wave function lives, doesn’t even have a recognizable notion of lengths in general, much less wavelengths in particular.

I’ll explain that last statement next time, when we look at the nature of the QFT wave function that corresponds to having a single QFT Bohron.

A Profound Change of Perspective

But before we conclude for the day, let’s take a moment to contemplate the remarkable change of perspective that is coming into our view, as we migrate our thinking from QM of the 1920s to modern QFT. In both cases, our Bohron of definite momentum is certainly associated with a definite wavelength; we can see that both in Fig. 3 and in Fig. 4. The formula for the relation is well-known to scientists; the wavelength λ for a Bohron of momentum P1 is simply

where h is Planck’s famous constant, the mascot of quantum physics. Larger momentum means smaller wavelength, and vice versa. On this, QM and QFT agree.

But compare:

• in QM, this wavelength sits in the wave function, and has nothing to do with waves in physical space;
• in QFT, the wavelength is not found in the field’s wave function; instead it is found in the field itself, and specifically in its ripples, which are waves in physical space.

I’ve summarized this in Table 1.

Table 1: The Bohron with definite momentum has an associated wavelength. In QM, this wavelength appears in the wave function. In QFT it does not; both the wavelength and the momentum are found in the field itself. This has caused no end of confusion.

Let me say that another way. In QM, our Bohron is a particle; it has a position, cannot spread out in physical space, and has no wavelength. In QFT, our Bohron is a “particle”, a wavy object that can spread out in physical space, and can indeed have a wavelength. (This is why I’d rather call it a wavicle.)

[Aside for experts: if anyone thinks I’m spouting nonsense, I encourage the skeptic to simply work out the wave function for phonons (or their counterparts with rest mass) in a QM system of coupled balls and springs, and watch as free QFT and its wave function emerge. Every statement made here is backed up with a long but standard calculation, which I’m happy to show you and discuss.]

I think this little table is deeply revealing both about quantum physics and about its history. It goes a long way toward explaining one of the many reasons why the brilliant founding parents of quantum physics were so utterly confused for a couple of decades. [I’m going to go out on a limb here, because I’m certainly not a historian of physics; if I have parts of the history wrong, please set me straight.]

Based on experiments on photons and electrons and on the theoretical insight of Louis de Broglie, it was intuitively clear to the great physicists of the 1920s that electrons and photons, which they were calling particles, do have a wavelength related to their momentum. And yet, in the late 1920s, when they were just inventing the math of QM and didn’t understand QFT yet, the wavelength was always sitting in the wave function. So that made it seem as though maybe the wave function was the particle, or somehow was an aspect of the particle, or that in any case the wave function must carry momentum and be a real physical thing, or… well, clearly it was very confusing. It still confuses many students and science writers today, and perhaps even some professional scientists and philosophers.

In this context, is it surprising that Bohr was led in the late 1920s to suggest that electrons are both particles and waves, depending on experimental context? And is it any wonder that many physicists today, with the benefit of both hindsight and a deep understanding of QFT, don’t share this perspective?

In addition, physicists already knew, from 19th century research, that electromagnetic waves — ripples in the electromagnetic field, which include radio waves and visible light — have both wavelength and momentum. Learning that wave functions for QM have wavelength and describe particles with momentum, as in Fig. 3, some physicists naturally assumed that fields and wave functions are closely related. This led to the suggestion that to build the math of QFT, you must go through the following steps:

• first you take particles and describe them with a wave function, and then
• second, you make this wave function into a field, and describe it using an even bigger wave function.

(This is where the archaic terms “first quantization” and “second quantization” come from.) But this idea was misguided, arising from early conceptual confusions about wave functions. The error becomes more understandable when you imagine what it must have been like to try to make sense of Table 1 for the very first time.

In the next post, we’ll move on to something novel: images depicting the QFT wave function for a single Bohron. I haven’t seen these images anywhere else, so I suspect they’ll be new to most readers.

Tracks and footprints found in New Mexico are by far the earliest evidence of people using primitive vehicles to transport things

NASA's Juno spacecraft swooped in for a close look at a massive thunderstorm on Jupiter, revealing that it may have similarities to storms on Earth

When Robert F. Kennedy Jr. was nominated to be Secretary of Health & Human Services, I called him an "extinction-level threat" to public health. Here's how he will attempt to make vaccines extinct in the US.

The post How Robert F. Kennedy Jr. will undermine and ultimately destroy US vaccination programs first appeared on Science-Based Medicine.

When offered a choice of bowls, free-ranging dogs in India tend to approach a yellow one much more than blue or grey

The journey to Mars will subject astronauts to extended periods of exposure to radiation during their months-long travel through space. While NASA’s Artemis 1 mission lasted only a matter of weeks, it provided valuable radiation exposure data that scientists can use to predict the radiation risks for future Mars crews. The measurements not only validated existing radiation prediction models but also revealed unexpected insights about the effectiveness of radiation shielding strategies too. 

Space radiation poses one of the most significant health risks for astronauts travelling beyond Earth’s magnetic field. Unlike the radiation from medical X-rays or nuclear sources on Earth, space radiation includes high-energy galactic cosmic rays and solar particle events that can penetrate traditional shielding materials. When these particles collide with human tissue, they can damage DNA, increase cancer risk and weaken the immune system. The effects are cumulative too, with longer missions like a journey to Mars significantly increasing exposure and health risks. 

Artist’s illustration of ultra-high energy cosmic rays

The International Space Station crews receive radiation doses similar to nuclear power plant workers due to a little protection from Earth’s magnetosphere, but astronauts traveling to Mars would face much higher exposure levels during their multi-month journey. NASA estimates that a mission to Mars could expose astronauts to radiation levels that exceed current career exposure limits, making effective radiation shielding one of the key challenges for deep space exploration.

A full-disk view of Mars, courtesy of VMC. Credit: ESA

A paper recently published by a team led by Tony C Slaba from the Langley Research Centre at NASA, they use computer models and data from on-board detectors to assess the health risk to long term space flight. The data is taken from the International Space Station (ISS,) the Orion Spacecraft, the BioSentinel CubeSat and from receivers on the surface of Mars. Collectively this data enables a full mission profile to be modelled for a Martian journey. The data was captured during the time period of the Artemis-1 mission, just under one month in duration.

NASA’s Orion spacecraft will carry astronauts further into space than ever before using a module based on Europe’s Automated Transfer Vehicles (ATV). Credit: NASA

Space radiation comes in two primary forms that pose risks to astronauts and spacecraft. Solar Particle Events occur during solar storms, releasing intense bursts of energetic particles from the Sun, while Galactic Cosmic Rays represent a constant stream of highly penetrating radiation from deep space. The findings enabled the team to assess current models for accuracy. They found that predictions match actual measurements to within 10-25% for the International Space Station, 4% for deep space conditions, and 10% for the Martian surface. This level of precision gives confidence in the existing models and in planning radiation protection for future missions.

They also found that, having assessed traditional shielding approaches, that they are largely ineffective against Galactic Cosmic Rays. In some cases, excessive shielding or inappropriate material choices can even amplify radiation exposure through secondary particle production. This occurs when the ‘original radiation’ creates a cascade of new particles on impact that can be more dangerous than the original radiation! They found that radiation levels vary substantially depending on location and the specific shielding configurations used! Quite the headache for engineers!

Radiation exposure is one of the greatest challenges in human space exploration. The study shows that our models for assessing radiation risk are reliable and that the ability to accurately assess those risks is crucial for protecting astronauts from serious health consequences. Having a good understanding of the risk directly influences how spacecraft are engineered, and plays a key role in mission planning for trips beyond Earth orbit. More work is needed now in the design of radiation protection systems if our space travellers are to be better protected from the long term risks posed by radiation.

Source : Validated space radiation exposure predictions from earth to mars during Artemis-I

The post We Know How Much Radiation Astronauts Will Receive, But We Don’t Know How to Prevent it appeared first on Universe Today.

Anthropogenic climate change is creating a vicious circle where rising temperatures are causing glaciers to melt at an increasing rate. In addition to contributing to rising sea levels, coastal flooding, and extreme weather, the loss of polar ice and glaciers is causing Earth’s oceans to absorb more solar radiation. The loss of glaciers is also depleting regional freshwater resources, leading to elevated levels of drought and the risk of famine. According to new findings by an international research effort, there has been an alarming increase in the rate of glacier loss over the last ten years.

The research was conducted by the Glacier Mass Balance Intercomparison Exercise (GlaMBIE) team, a major research initiative coordinated by the World Glacier Monitoring Service (WGMS). Located at the University of Zurich in collaboration with the University of Edinburgh and Earthwave Ltd, this international data repository and data analyzing service generates community estimates of glacier mass loss globally. The paper that details their research and findings, “Community estimate of global glacier mass changes from 2000 to 2023,” was published on February 19th in the journal Nature.

As part of their efforts, the team coordinated the compilation, standardization, and analysis of field measurements and data from optical, radar, laser, and gravimetry satellite missions. These include satellite observations from NASA’s Terra Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and Ice, Cloud, and Land Elevation Satellite-2 (ICESat-2), the NASA-DLR Gravity Recovery and Climate Experiment (Grace), the GLR’s TanDEM-X mission, and the ESA’s CryoSat missions, and more.

Combining data from multiple sources, the Glambie team produced an annual time series of global glacier loss from 2000 to 2023. In 2000, glaciers covered about 705,221 square km (272,287 mi2) and held an estimated 121,728 billion metric tons (134,182 US tons) of ice. Over the next twenty years, they lost 273 billion tonnes of ice annually, approximately 5% of their total volume, with regional losses ranging from 2% in the Antarctic and Subantarctic to 39% in Central Europe. To put that in perspective, this amounts to what the entire global population consumes in 30 years.

In short, the amount of ice lost rose to 36% during the second half of the study (2012 and 2023) compared to the first half (2000-2011). Glacier mass loss over the whole study period was 18% higher than the meltwater from the Greenland Ice Sheet and more than double that from the Antarctic Ice Sheet. Michael Zemp, a noted glaciologist who co-led the study, said in an ESA press release:

“We compiled 233 estimates of regional glacier mass change from about 450 data contributors organized in 35 research teams. Benefiting from the different observation methods, Glambie not only provides new insights into regional trends and year-to-year variability, but we could also identify differences among observation methods. This means that we can provide a new observational baseline for future studies on the impact of glacier melt on regional water availability and global sea-level rise.”

This photograph, taken in 2012, shows the Golubin Glacier in Kyrgyzstan, in Central Asia. Credit: M. Hoelzle (2012)

Globally, glaciers collectively lost 6,542 tonnes (7,210 tons) of ice, leading to a global sea-level rise of 18 mm (0.7 inches). However, the rate of glacier ice loss increased significantly from 231 billion tonnes per year in the first half of the study period to 314 billion tonnes per year in the second half – an increase of 36%. This rise in water loss has made glaciers the second-largest contributor to global sea-level rise, surpassing the contributions of the Greenland Ice Sheet, Antarctic Ice Sheet, and changes in land water storage. Said UZH glaciologist Inés Dussaillant, who was involved in the Glambie analyses:

“Glaciers are vital freshwater resources, especially for local communities in Central Asia and the Central Andes, where glaciers dominate runoff during warm and dry seasons. But when it comes to sea-level rise, the Arctic and Antarctic regions, with their much larger glacier areas, are the key players. However, almost Thione-quarter of the glacier contribution to sea-level rise originates from Alaska.”

These results will provide environmental scientists with a refined baseline for interpreting observational differences arising from different methods and for calibrating models. They hope this will help future studies of global ice loss by narrowing the projection uncertainties for the twenty-first century. These research findings are the culmination of many years of cooperative studies and observations, which included the use of satellites that were not specifically designed to monitor glaciers globally. As co-author Noel Gourmelen, a lecturer in Earth Observation of the Cryosphere at the University of Edinburgh, said:

“The research is the result of sustained efforts by the community and by space agencies over many years, to exploit a variety of satellites that were not initially specifically designed for the task of monitoring glaciers globally. This legacy is already producing impact with satellite missions being designed to allow operational monitoring of future glacier evolution, such as Europe’s Copernicus CRISTAL mission which builds on the legacy of ESA’s CryoSat.”

The study also marks an important milestone since it was released in time for the United Nations’ International Year of Glaciers’ Preservation and the Decade of Action for Cryospheric Sciences (2025–2034). Said Livia Jakob, the Chief Scientific Officer & Co-Founder at Earthwave, hosted a large workshop with all the participants to discuss the findings. “Bringing together so many different research teams from across the globe in a joint effort to increase our understanding and certainty of glacier ice loss has been extremely valuable. This initiative has also fostered a stronger sense of collaboration within the community.”

The study also illustrates the importance of collective action on climate change, which is accelerating at an alarming rate. Research that quantifies glacial loss, rising sea levels, and other impacts is key to preparing for the worst. It’s also essential to the development of proper adaptation, mitigation, and restoration strategies consistent with the recommendations made by the UN Intergovernmental Panel on Climate Change (IPCC).

Further Reading: ESA

The post Glaciers Worldwide are Melting Faster Causing Sea Levels to Rise More appeared first on Universe Today.

Satellites often face a disappointing end: despite having fully working systems, they are often de-orbited after their propellant runs out. However, a breakthrough is on the cards with the launch of China’s Shijian-25 satellite which has been launched into orbit to test orbital refuelling operations. The plan; docking with satellite Beidou-3 G7 and transferring 142 kilograms of hydrazine to extend its life by 8 years! It’s success will mean China plans to develop a network of orbital refuelling stations!

Like cars on Earth, satellites need fuel to manoeuvre and for their constantly decaying orbits to be boosted. But unlike vehicles on the ground, when satellites run out of propellant, they become expensive space debris. This challenge has driven the development of orbital refuelling technology, which could extend satellite lifespans and transform space operations.

An artist’s conception of ERS-2 in orbit. ESA

The International Space Station (ISS) offers one of the most well known examples of an orbiting ‘satellite’ and it too needs to deal with boosting its orbit. The problem is the drag imposed upon the structures by gas in our atmosphere. In the case of the ISS, docked supply craft are typically used to fire their engines to reposition ISS to the correct altitude. Without these periodic “orbital boosts,” the ISS would eventually lose altitude and reenter the atmosphere.

The International Space Station (ISS) in orbit. Credit: NASA

A significant milestone in autonomous refuelling came in 2007 with DARPA’s Orbital Express mission. This demonstration involved two spacecraft: the ASTRO servicing vehicle and a prototype modular satellite called NextSat. Over three months, they performed multiple autonomous fuel transfers and component replacements, proving that robotic spacecraft could conduct complex servicing operations without direct human control.

The technology continues to advance with China’s Shijian-25 satellite (launched on 6 January 2025) representing another step forward in orbital refuelling capabilities. The mission aims to demonstrate refuelling operations in geosynchronous orbit approximately 36,000 kilometres above Earth. This is particularly significant because geosynchronous orbits often host communications satellites that benefit from life extension.

The technical challenges of orbital refuelling are considerable though. Spacecraft must achieve extremely precise rendezvous and docking while travelling in excess of 28,000 kilometres per hour. The fuel transfer system must prevent leaks, which could be hazardous to both spacecraft and create hazardous debris. Adding to the challenge is that many satellites were never designed with refuelling in mind, lacking any form of standardised fuel ports or docking interfaces.

Orange balls of light fly across the sky as debris from a SpaceX rocket launched in Texas is spotted over Turks and Caicos Islands on Jan. 16, in this screen grab obtained from social media video. Credit: Marcus Haworth/Reuters

Looking ahead, several companies and space agencies are developing orbital refuelling systems. These range from dedicated “gas station” satellites to more versatile servicing vehicles that can perform repairs and upgrades alongside refuelling. As the technology advances, it could significantly change how we operate in space, making satellite operations more sustainable and cost-effective.

Source : China successfully sent Shijian-25 satellite

The post A Chinese Satellite Tests Orbital Refuelling appeared first on Universe Today.

Astronomers have known for some time that nearby supernovae have had a profound effect on Earth’s evolution. For starters, Earth’s deposits of gold, platinum, and other heavy metals are believed to have been distributed to Earth by ancient supernovae. The blasts of gamma rays released in the process can also significantly affect life, depleting nitrogen and oxygen in the upper atmosphere, depleting the ozone layer, and causing harmful levels of ultraviolet radiation to reach the surface. Given the number of near-Earth supernovae that have occurred since Earth formed 4.5 billion years ago, these events likely affected the evolution of life.

In a new paper by a team of astronomers from the University of California Santa Cruz (UCSC), a nearby supernova may have influenced the evolution of life on Earth. According to their findings, Earth was pummeled by radiation from a nearby supernova about 2.5 million years ago. This burst of radiation was powerful enough to break apart the DNA of living creatures in Lake Tanganyika, the deepest body of water in Africa. This event, they argue, could be linked to an explosion in the number of viruses that occurred in the region.

The study was led by Caitlyn Nojiri, a recent graduate of the USCS Department of Astronomy and Astrophysics. She was joined by Enrico Ramirez-Ruiz, a USCS Professor of astronomy and astrophysics, and Noémie Globus, a postdoctoral fellow at USCS and a member of the Kavli Institute for Particle Astrophysics and Cosmology at Stanford University and the Astrophysical Big Bang Laboratory. The paper that describes their findings appeared on January 15th in the journal Astrophysical Journal Letters.

The image of Lake Tanganyika was acquired in June 1985. Credit: NASA

For their study, the team examined samples of iron-60 retrieved from the seafloor of Lake Tanganyika, the 645 km-long (400 mi) lake in Africa’s Great Rift Valley that borders Burundi, Tanzania, Zambia, and the Democratic Republic of Congo. This radioactive isotope of iron is produced by supernovae and is extremely rare on Earth. They obtained age estimates based on how much the samples had already broken down into nonradioactive forms. This revealed two separate ages for the samples, some 2.5 million years old and the others 6.5 million years old.

The next step was to trace the origin of the iron isotopes, which they did by backtracking the Sun’s motions around the center of the Milky Way. Roughly 6.5 million years ago, our Solar System passed through the Local Bubble, a region of lower density in the interstellar medium (ISM) of the Orion Arm in the Milky Way. As the Solar System entered the Bubble’s stardust-rich exterior, Earth was seeded with the older traces of iron-60. Between 2 and 3 million years ago, a neighboring star went supernova, seeding Earth with the younger traces of iron-60.

To confirm this theory, Nojiri and her colleagues conducted a simulation of a near-Earth supernova, which indicated that it would have bombarded Earth with cosmic rays for 100,000 years after the blast. This model was consistent with a previously recorded spike in radiation that hit Earth around that time. Given the intensity of the radiation, this raised the possibility that it was enough to snap strands of DNA in half. In the meantime, the authors came upon a study of virus diversity in one of Africa’s Rift Valley lakes and saw a possible connection. Said Nojiri in a UCSC news release:

“It’s really cool to find ways in which these super distant things could impact our lives or the planet’s habitability. The iron-60 is a way to trace back when the supernovae were occurring. From two to three million years ago, we think that a supernova happened nearby. We saw from other papers that radiation can damage DNA. That could be an accelerant for evolutionary changes or mutations in cells. We can’t say that they are connected, but they have a similar timeframe. We thought it was interesting that there was an increased diversification in the viruses.”

Lead author Caitlyn Nojiri is now applying for graduate school and hopes to get a Ph.D. in astrophysics. Credit: UCSC

Shortly after their paper was published, Nojiri became the first UCSC undergraduate to be invited to give a seminar at the Center for Cosmology and AstroParticle Physics (CCAPP) at Ohio State. Nojiri did not initially set out to be an astronomer but eventually arrived at UCSC, where Prof. Ramirez-Ruiz encouraged her to apply for the University of California Leadership Excellence through Advanced Degrees (UC LEADS) program. This program is designed to identify undergraduate students from diverse backgrounds who have the potential to succeed in STEM.

She also participated in the Lamat program (“star” in Mayan), which was founded by Ramirez-Ruiz to teach students with great aptitude and nontraditional backgrounds how to conduct research in astronomy. Because of her experience with these programs, Nojiri has decided to apply for graduate school and become an astrophysicist.

“People from different walks of life bring different perspectives to science and can solve problems in very different ways,” said Ramirez-Ruiz. “This is an example of the beauty of having different perspectives in physics and the importance of having those voices.”

Further Reading: UC Santa Cruz, The Astrophysical Journal

The post New Study Proposes that Cosmic Radiation Altered Virus Evolution in Africa appeared first on Universe Today.