Archive for the 'Astronomy' Category

Oct 21 2022

More Precise Measure of Hubble Constant Solidifies Mystery

Published by under Astronomy

Cosmologists have recently published the updated results of an extensive analysis of the overall structure of the cosmos, with interesting results. It both solidifies our current understanding of the universe, but also reinforces a conflict that scientists have not been able to solve.

The story begins with Type IA supernova. A supernova is when a star explodes because of runaway fusion in its core. Different stars of different masses and compositions will explode with different energies and therefore intrinsic brightness. But a Type IA is caused by a white dwarf star in a binary system which is leaching matter off its companion. The white dwarf slowly gains mass until it reaching the Chandrasehkar limit, the point at which its gravity overcomes the outward pressure of heat and energy, the star then collapses and goes supernova. This means that all Type IA supernova are the exact same mass when they explode, which further means that they should have the same intrinsic brightness. In reality there is some variability in peak brightness based on other variables like composition, but astronomers have learned to make adjustments so as to arrive at a precise measure of intrinsic brightness.

Knowing the intrinsic brightness of an astronomical object is hugely useful. It means we can calculate based on its apparent brightness exactly how far away it is. Such objects are known as standard candles, and the Type IA supernova are perhaps the most useful we have. Type IAs are also really bright, outshining entire galaxies, which further means we can see them really far away, about 10 billion light years. There is also a lot of them happening around the universe. Looking far away is also looking back in time, so Type IAs not only allow us to measure the cosmos, but also to measure it throughout its history (back to 10 billion years).

It was observations of Type IA supernova that allowed astronomers to first determine that the universe is not only expanding, it’s accelerating. Since then astronomers have been gathering data on Type IAs in a project called Pantheon. The catalogued more than 1,000 Type IAs providing the most precise measure of the rate of the universe’s expansion, called the Hubble Constant. Now they have published what they are calling Pantheon+, with an expanded database of over 1,500 Type IA supernova. They have also been able to tweak their methods to make more precise measurements, account for more factors, and essentially give a much more detailed account of the Hubble Constant at different times throughout the history of the universe.

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Oct 17 2022

Electric Universe Is Crank Pseudoscience

Science is fun, interesting, and empowering, but it is also hard, especially at advanced levels. Even at a basic level, science forces you to think clearly, precisely, logically, and objectively. It therefore challenges our preconceptions, our biases, our hopes and desires and replaces these things with indifferent reality. Science becomes progressively tricky the more advanced it becomes, requiring an increasing fund of knowledge and mastery over subtle concepts and technical skills in order to be able to take the next step. At the cutting edge of science, nothing short of years of dedicated study is necessary to engage meaningfully with the enterprise of advancing human scientific knowledge. You also have to be able to engage productively with a community of scientists, all picking apart each other’s work.

It’s for these reasons that there is a lot of bad science out there. There are also those who prioritize things other than the pursuit of scientific knowledge, such as money, fame, or advancing an ideology. Many people mean well, but simply get the science wrong. Even successful scientists can make egregious errors, stubbornly stick to false ideas, or let their own ideology get in the way. So what is the average science enthusiast to do? Unless you have a fairly high level of scientific expertise in general and also in a specific field, you cannot hope to engage with the cutting edge of that field. To some extent, you have to trust the experts, but what if the experts disagree, or some of them are just wrong?

There is no easy answer to this, but there are skills and methods other than actual expertise in a specific field that can help a layperson have a pretty good idea which experts to listen to. This requires some scientific literacy, especially about how proper science operates. It also requires a certain amount of critical thinking skills – knowing something about logic, self-deception, and the nature of evidence. Further, we can learn to recognize the different types of pseudoscience and pseudoscientific behaviors, which can act as reliable red-flags to help spot fake science. Recently promoters of the Electric Universe have appeared in the comments to this blog, and this is a good opportunity to review these red flags.

The idea of the electric universe (EU) is that electromagnetism actually does most of the large-scale heavy lifting when it comes to the structure of the cosmos, displacing gravity as the main long-distance force. There are different flavors of EU, with some doing away with gravity completely, and others allowing for some gravity (to help explain phenomena EU can’t) but still relegate it to a minor role. One major example is that EU proponents believe stars are fueled by electromagnetism, and not by gravity-induced fusion. Here are two great videos that give a concise summary of the history of EU belief and why it is complete and utter nonsense. But I will review the major problems with EU and use them as examples of crank pseudoscience.

Crank pseudoscience is a flavor of pseudoscience that operates at a technically sophisticated level, but is missing some of the key elements of actual science that doom proponents to absurdity. But it also contains many of the generic features of pseudoscience. Let’s review, starting with features more typical of crank pseudoscience.

Does not engage meaningfully with the scientific community.

Science is a collaborative effort, especially at the advanced cutting edge level. This is because it is so difficult at this level, you need the self-corrective process of peer-review, rejection of error, criticism of wrong ideas, challenges for evidence and by alternative theories, etc. Without this self-corrective process, fringe groups or individuals tend to drift off from reality into a fantasy land of their own creation, although gilded with the superficial trappings of science. EU proponent Montgomery Childs exemplifies this in an interview (in the second video above) when he tries lamely to justify not bothering to publish any of his findings in scientific journals. Actual experts in plasma physics and cosmology therefore just ignore his fringe work – unless they have data to look at, they don’t have much of a choice. This is a core feature of crank pseudoscience – cranks tend to toil alone or in small fringe echochambers and not engage with proper experts.

 

Work outside their actual area of expertise (if they have one).

Often we see scientists or engineering getting into crank science when they venture beyond their specific area of expertise. Sometimes this is just hubris – in fact we joke about the Nobel Prize effect, where some Nobel Prize winners go on to support pseudoscience later in their career. There is also an aging-scientist effect where researchers toward the end of their career start looking at their legacy, or lack of one, and want to make a big splash somewhere. Some choose a small fringe pond where their credentials make them a big fish, and start promoting nonsense. The problem, of course, if that being an expert in one area does not equip you to contradict actual experts in a separate field. Electrical engineers are not cosmologists or physicists. It is therefore helpful to see what the most appropriate experts say about a theory, not just anyone with letters after their name. Actual experts reject the EU as completely nonsense (with good reason), and its proponents are all in unrelated fields.

 

Make grandiose claims while minimizing actual scientific knowledge.

The EU claims to overhaul much of science, which is itself a red flag. It is hard to prove that established science is all wrong, and it’s getting harder as science advances and the foundational concepts of science are increasingly supported by evidence and derivative theories. What cranks often do is grossly exaggerate what is currently unknown in a scientific field, or the meaning of anomalies, and they downplay what is known with confidence. This often become simply lying, making boldly false claims about the state of the science. EU proponents, for example, ignore or deny the evidence for the Big Bang, black holes, stellar fusion, and gravity. The claim that they have overturned pretty much all of astrophysics, stellar astronomy, General Relativity, and more – all on the flimsiest of pretexts. In other words, they reject theories supported by a mountain of evidence, and replace them with theories that have (at best) an ant hill.

 

They don’t actually explain 0r predict anything.

Another core feature of science is that it makes testable predictions. What this means is that there has to be some way to determine if one theory is more correct than another, because they make different predictions about what we will observe in the universe or the result of experiments. Scientific theories also should have explanatory power (it can explain what we see) – but this is actually necessary but insufficient feature of science. Astrology has explanatory power – if you are willing to just make up BS explanations for stuff. It’s easy, and pattern-seeking humans are good at, finding explanations of stuff. The problem with EU is that it really does neither – predict or explain. In fact, shifting from current cosmological theories to EU would be a massive step backwards. EU cannot explain a ton of established phenomena that are well explained by current theories, such as the evidence for black holes or dark matter, the lifecycle of stars, the existence of neutrinos from stellar fusion, and many more. There are also fundamental problems with EU, such as the known behavior of electromagnetism and charged particles. What EU proponents do, rather, is simply hunt for patterns, and then make very superficial connections between some aspect of EU theory and some astronomical phenomenon.

This is what triggered some of the comments – the regular rings of dust found around WR140, caused by the periodicity of the wind-binary star system. EU proponents said – look, concentric rings. We see those in the plasma dohickey thing. They then count that as a “prediction” when it was actually just retrofitting, and not very well. They falsely call the rings “perfect” when it is the very imperfections in the rings that can be accounted for by the astronomical explanation.

 

Portray the scientific community as a conspiracy of the small-minded.

If you have a nonsensical fringe theory and don’t publish your findings (except in fringe journals created for that purpose), it’s likely that the broader scientific community with ignore or reject your claims. They should – you have not earned their assent by demonstrating your claims with objective and publicly available evidence. When that happens, cranks universally claim they are the victim of a conspiracy. They don’t self-correct, address legitimate criticisms, recognize the shortcomings of their theories, do better experiments or, in short, engage in legitimate science. They cry foul. They say something to the effect that “mainstream” science is all a conspiracy, and scientist are simply too dumb or too scared to recognize their towering genius. This is the point that self-comparisons to Galileo or Einstein are typically brought out.

EU proponents do this in spades. There is a large, vibrant, world-wide community of astrophysicists, all at different parts of their career, in different countries and institutions, just trying to figure out how the universe works and hopefully make a name for themselves doing so. Yet a few fringe scientists, without the proper expertise, allege they have proven all of them hopelessly wrong, because they are all biased or don’t know what they are doing. And they are stubbornly not convinced by silly superficial evidence its proponents won’t bother to publish. Imagine!

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Oct 13 2022

Another Possible Technosignature Falls

Published by under Astronomy

One day it may turn out that a potential sign of alien technology (technosignature) turns out to be just that. That is the best hope of finding evidence for life outside our solar system in my lifetime. But that day has not yet arrived, and another potential candidate (although this one was pretty weak) has found a natural explanation.

Of course no one knows, because we only have one example of life and a technological civilization, but if I had to guess I would say the universe is teeming with life. We’ve now confirmed what scientists long suspected, that our solar system is not unique or rare. Most stars have lots of planets around them, including rocky worlds within their habitable zone. Also, life seems to have arisen very quickly on Earth, as soon as the conditions were compatible with organic life. We may also find that life once existed on Mars, and may still exist in one or more ocean world, like Europa. Discovering even microbial life that originated independently from life on Earth would be huge – it would give us a second data point. It would confirm that life is likely everywhere it can form.

The probability, and therefore density, of technological civilizations is another matter entirely. It took the Earth about 4 billion years of tinkering with life before a technological species arose, and it happened (so far) only once. We have also not been around for very long, and there are many plausible scenarios by which our geological presence on this planet may be relatively brief. The famous Drake Equation mathematically frames the question, but that does not help us fill in all the variables. We simply don’t know. It is possible we are the only current technological species in the galaxy, or there may be hundreds, or even thousands. It also possible that ancient technological species, now long dead, have left behind evidence of their existence – their radio signals still streaming through space, or massive megastructures that reengineered entire stellar systems.

The reason I think finding such evidence is our best hope of detecting non-Sol life is that astronomers can search vast parts of the universe, and frequently detect even extremely rare situations and events. We have increasingly powerful and sophisticated instruments, like the James Webb telescope, that will help us find such things, if they are out there. Webb recently helped astronomers resolve an anomalous finding, although this one has a natural explanation (as all anomalies have gone before it, so far).

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Oct 10 2022

Nitrous Oxide as a Biosignature

Published by under Astronomy

I still find it amazing that we can look at an astronomical object light years away and determine its chemical composition in detail. This is referred to as spectral analysis – looking at either absorption or emission lines in the wavelengths of light. Isaac Newton was the first to demonstrate that white light from the sun is actually composed of the full spectrum of visible light, which can be separated by passing through a prism which bends light of different colors to different degrees, causing it to spread out into the familiar rainbow pattern. However, Newton was not the first to discover this effect, but prior to his experiments it was believed the prisms colored the light. Newton demonstrated that the colors were already there.

In 1802, William Hyde Wollaston improved on the prism design to produce more detailed spectra. He discovered black bands of missing wavelengths in the light. These are absorption lines – chemicals will absorb specific wavelengths of light depending on their chemical structure (corresponding to the orbits of electrons which absorb the energy of light to jump to a higher energy orbit), with the pattern of absorption lines being a signature of the specific chemical. There are also emission lines in which specific wavelengths of light are created depending on the source of the light. Therefore we can tell the chemical composition of a star by looking at its emission lines, and we can also tell its temperature as different elements and chemical have peak emissions at different temperatures. When starlight passes through a gas cloud and material in the cloud will absorb specific frequencies of light, telling us what it is made of.

Therefore, if an exoplanet with an atmosphere is discovered through the transit method (it causes the light of its star to dim when it blocks a small amount of it as it passes in front), then we may be able to detect some of the light from that star as it passes through the atmosphere of the planet. This requires high resolution imaging, but within our current capabilities for some exoplanets (and now extended with the James Webb Space Telescope). With spectral analysis we get information about the composition and temperature of the exoplanet’s atmosphere. Astronomers are most interested in using this method to look for signs of life (so-called biosignatures). What would a sign of life in a planet’s atmosphere be?

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Sep 30 2022

Webb and Hubble Image Dart Hitting Its Target

Published by under Astronomy

By now you have likely seen the images of NASA’s DART spacecraft smashing into the asteroid, Dimorphos, a small asteroid in orbit around a larger asteroid, Didymos. Here is the streaming video from DART itself, showing right up to the moment of impact. Many telescopes were focused on this event, including (for the first time) both the Webb and Hubble space-based telescopes. Why did NASA deliberately crash a spacecraft?

DART stands for “double asteroid redirect test” – it is designed to test a system for redirecting the path of an asteroid by smashing stuff into it. It’s a double asteroid because Dimorphos and Didymos are a double asteroid system. DART included a DRACO camera – Didymos Reconnaissance and Asteroid Camera for Optical navigation, used to support the SMART-nav system – Small-body Maneuvering Autonomous Real Time Navigation (SMART Nav). NASA loves its acronyms. Part of the DART test was to see if these systems worked, if the craft could successfully navigate itself precisely enough to score a direct hit on a tiny asteroid. It did.

But also NASA wanted to see the results, and this is where Webb and Hubble come in, as well as many ground-based telescopes. They wanted to image the composition and speed of the ejecta. Specifically – would DART kick off a cloud of fine powder, or would larger chunks of rock break off the asteroid? When redirecting an asteroid the last thing we would want to do is create a debris field of large chunks of rock. Which brings us to the overall goal of the mission, to protect the Earth from an asteroid impact.

Asteroid impacts are inevitable, with large impact increasingly rare, but they do occasionally happen. Just ask the dinosaurs, except you can’t because they were all killed by an asteroid impact. Statistically it will likely be a long time before a biosphere-killing asteroid hits the Earth again, but it will likely happen eventually. There can also be smaller, but still catastrophic, asteroids headed our way, ones large enough to take out a major city, cause a devastating tsunami, or even threaten a continent. We don’t have to wait helplessly while a killer asteroid head our way. We can push it into a different trajectory, so that it safely misses us.

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Sep 08 2022

Two New Nearby SuperEarths

Published by under Astronomy

As a SciFi fan, I have a lot of pet peeves (as most hard core fans probably do). While I love the freedom and imagination of speculative fiction, it’s easy to fall into common tropes that have emerged to facilitate story telling or simply due to lack of imagination. The problem is worse with science fiction in film and TV because of budgetary concerns (although CG is making this less of a restraint). For example, aliens tend to be far too human and generally have a monolithic culture.

Alien worlds also are too frequently Earth-like (mostly because the filming takes place on Earth). It’s one thing if your starship is visiting a world because it is habitable, but often our heroes come upon an apparently random planet that is unrealistic Earth-like. There are many exceptions to this in science fiction film and literature, but it still happens frequently, enough to be considered a trope. Think about all the ways in which the environment of even an Earth-sized planet in its habitable zone could vary. There’s always not only oxygen (even on apparently barren worlds) but enough oxygen. The gravity is always about 1G, the sun is always a nice yellow sun, and while the temperature may vary it’s always within survivable range.

The reality is that, by chance alone, something would be off. Now that we have the ability to actually discover exoplanets, that is exactly what we are finding. Astronomers estimate that there are likely between 300 million and 6 billion Earth-like planets in the milky way. That’s a big number, but there are 100-400 billion stars in the Milky Way, so that means on average about 1% of star systems contain an Earth-like planet. Also, what do we consider “Earth-like”? Generally that is any planet that is rocky and is in its star’s habitable zone, which means there can be sustainable liquid water on the surface. But that allows for a great deal of variability.

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Sep 06 2022

What To Make of the Artemis Launch Delays

Published by under Astronomy,Technology

As you are likely aware, NASA’s latest big project is the space launch system (SLS) which is the rocket system that will be used by the Artemis program to return astronauts to the Moon. The SLS also contains the Orion capsule, which is a deep space craft capable of holding four crew for missions up to 21 days. It is currently the only deep space capsule, capable of the high speed reentry required for return from the Moon.

Artemis I, and uncrewed test mission, was scheduled to launch on Monday August 29th. This launch had to be scrubbed because of the main engines were not at the right operating temperature. The problem turned out to be a faulty sensor. However, there are limited launch windows (only a couple of hours) and the problem could not be identified and fixed within the launch window, so the launch was scrubbed. It was then rescheduled for Saturday September 3rd. This time the problem was a real leak in the hydrogen fuel tanks, likely a problem with one of the seals. They failed to fix the problem on the launch pad so again had to scrub the launch. Leaking hydrogen is a serious problem; beyond a certain point there is a risk of the leaked hydrogen exploding on launch, and they were well beyond that safety point.

This shows how delicate this whole process is. It may be possible to fix the seal and the leak with the rocket still on the launch pad. However, the batteries used for the abort system are getting to the end of their optimal readiness window, and those batteries have to be swapped out in the engineering building. So the rocket has to be taken off the pad and brought there to reset everything to be ready for launch. This puts the next earliest launch date about six weeks off, in mid October.

Are these launch delays routine and expected or are they evidence that the SLS is a boondoggle, as its harshest critics maintain? I think it’s a little of both.

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Aug 01 2022

Lunar Pits Warm and Comfy

Published by under Astronomy

Building a base on the Moon in certainly going to be challenging. In fact, living anywhere other than the surface of the Earth is extremely challenging – the rest of our solar system is an unlivable hellscape. The thin biosphere clinging to the surface of Earth is the only place that humans can comfortably live (and even not everywhere there). But we will be returning to the Moon again with the upcoming Artemis mission, and this time NASA plans on staying, not just leaving behind “flags and footprints”. There are no current plans for a permanent moon base or settlement, but the work of Artemis will continue to lay the groundwork for eventually future bases.

The surface of the Moon is hostile to life in several respects. First, there is almost no atmosphere. Humans can survive in a hard vacuum for about 90 seconds, falling unconscious after 15-20. Second, the surface of the Moon is exposed to radiation (solar wind and cosmic rays) and micrometeors. There are filtered out on Earth by its thick atmosphere and magnetic field, neither of which protect the Moon. Finally, the temperature on the surface of the Moon varies from one extreme to the other – during the day surface temperatures reach 260 degrees Fahrenheit (126° Celsius), while nighttime temps can drop to -280 F (-173 C).

But these harsh conditions do not necessarily exist everywhere on the Moon. The hard vacuum, yes, there is simply no air on the Moon, which has too little gravity to hold onto a significant atmosphere. But there may be protection from the second two features: exposure to radiation and variable temperatures – in lunar pits, caves, and lava tubes.

Lava tubes exist on every rocky world in the solar system. They are channels through which molten lava flowed and eventually solidified, leaving behind solid tubes in the rock. You can explore lava tubes on Earth, such as in Hawaii. The size of lava tubes tends to correlate with the gravity of the world on which they occur, and the Moon’s light gravity (16.6% Earth’s gravity, or 0.166 g) allows for giant lava tubes. Recent evidence suggests they can be  1,600 to 3,000 feet (500 to 900 m) in diameter. This is large enough to contain a city. The big advantage of building a permanent base or settlement inside a lava tube is that the rocky covering will protect it from radiation and micrometeors.

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May 03 2022

Using the Sun as a Lens

Published by under Astronomy

Is it even theoretically possible to image in any detail the surface of an exoplanet light years away? An optical telescope would need to be many times the diameter of the Earth to produce such images. This “brute force” method of just building a giant telescope is probably never going to happen. Instead we need to find a more clever way, a method of exploiting the laws of physics to magnify distant images orders of magnitude beyond current technology. One idea gaining attention is using the sun as a giant gravitational lens.

In 1916 Einstein published his theory of General Relativity, which conceptualized gravity as a distortion of spacetime. He predicted that an object with a large gravitational field would even bend light. His predictions were validated with the 1919 total solar eclipse. During totality stars could be seen around the edge of the sun, and their apparent positions indicated that light from those stars had been bent as they passed near the sun. That validation gave a huge boost to acceptance of Einstein’s theory and made him a scientific superstar. Building on this idea he later predicted that a distant massive object with a light source directly behind it from the perspective of Earth would be surrounded by a ring of light from that more distant object – called an Einstein ring. Although relatively rare because they require a precise alignment, Hubble has found many examples.

In 1979 Von R. Eshleman wrote a paper in which he proposed that Einstein’s gravitational lens effect could be leveraged to image objects at interstellar distances. He wrote:

“The gravitational field of the sun acts as a spherical lens to magnify the intensity of radiation from a distant source along a semi-infinite focal line. A spacecraft anywhere on that line in principle could observe, eavesdrop, and communicate over interstellar distances, using equipment comparable in size and power with what is now used for interplanetary distances.”

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Apr 08 2022

Axiom 1 To Launch Today

Published by under Astronomy

That’s the plan anyway, weather permitting. While the launch itself is nothing new, the mission is a milestone for the space industry. The launch involves a SpaceX Falcon 9 rocket with the Dragon Crew Endeavor spacecraft – this will be the third launch for this spacecraft, highlighting the reusability of these capsules. Right now the launch is planned for 11:17 AM EDT, and you can watch coverage live at the Axiom website.

Notice that you can watch on Axiom, a private space company. While NASA will also be broadcasting the launch, they will not be providing their own clean feed. That’s because this is not primarily a NASA mission. In fact, for the first time, NASA will not be providing mission control, which instead will be run out of Axiom’s Houston command center. Further (and this is a first) the crew will be comprised of four private citizens.

“The astronauts onboard are all private citizens, with the mission commander, Michael López-Alegría, a previous NASA astronaut. The other three members, Larry Connor, Eytan Stibbe, and Mark Pathy are described by the company as “entrepreneurs” and “investors.””

These are not billionaires just going on a joyride, although they are all wealthy private citizens, each of whom paid $55 million dollars toward the mission. As stated, one is a prior NASA astronaut, also one a commercial pilot, and one a former military pilot. Any of them could quality as NASA astronauts. The AX-1 mission, as they are calling it, is a 10-day mission, with 8 days spent onboard the ISS conducting scientific experiments. NASA is providing some funding and logistical support, but this is primarily a commercial mission.

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