Astronomers have detected over 5,800 confirmed exoplanets. One extreme class is ultra-hot Jupiters, of particular interest because they can provide a unique window into planetary atmospheric dynamics. According to a new paper published in the journal Nature, astronomers have mapped the 3D structure of the layered atmosphere of one such ultra-hot Jupiter-size exoplanet, revealing powerful winds that create intricate weather patterns across that atmosphere. A companion paper published in the journal Astronomy and Astrophysics reported on the unexpected identification of titanium in the exoplanet's atmosphere as well.

For context, the most powerful particle accelerator on Earth, the Large Hadron Collider, accelerates protons to an energy of 7 Tera-electronVolts (TeV). The neutrino that was detected had an energy of at least 60 Peta-electronVolts, possibly hitting 230 PeV. That also blew away the previous records, which were in the neighborhood of 10 PeV.

Attempts to trace back the neutrino to a source make it clear that it originated outside our galaxy, although there are a number of candidate sources in the more distant Universe. //

Neutrinos, to the extent they're famous, are famous for not wanting to interact with anything. They interact with regular matter so rarely that it's estimated you'd need about a light-year of lead to completely block a bright source of them. Every one of us has tens of trillions of neutrinos passing through us every second, but fewer than five of them actually interact with the matter in our bodies in our entire lifetimes.

The only reason we're able to detect them is that they're produced in prodigious amounts by nuclear reactions, like the fusion happening in the Sun or a nuclear power plant. We also stack the deck by making sure our detectors have a lot of matter available for the neutrinos to interact with.

Almost no one ever writes about the Parker Solar Probe anymore.

Sure, the spacecraft got some attention when it launched. It is, after all, the fastest moving object that humans have ever built. At its maximum speed, goosed by the gravitational pull of the Sun, the probe reaches a velocity of 430,000 miles per hour, or more than one-sixth of 1 percent the speed of light. That kind of speed would get you from New York City to Tokyo in less than a minute. //

However, the smallish probe—it masses less than a metric ton, and its scientific payload is only about 110 pounds (50 kg)—is about to make its star turn. Quite literally. On Christmas Eve, the Parker Solar Probe will make its closest approach yet to the Sun. It will come within just 3.8 million miles (6.1 million km) of the solar surface, flying into the solar atmosphere for the first time.

Yeah, it's going to get pretty hot. Scientists estimate that the probe's heat shield will endure temperatures in excess of 2,500° Fahrenheit (1,371° C) on Christmas Eve, which is pretty much the polar opposite of the North Pole. //

I spoke with the chief of science at NASA, Nicky Fox, to understand why the probe is being tortured so. Before moving to NASA headquarters, Fox was the project scientist for the Parker Solar Probe, and she explained that scientists really want to understand the origins of the solar wind.

This is the stream of charged particles that emanate from the Sun's outermost layer, the corona. Scientists have been wondering about this particular mystery for longer than half a century, Fox explained.

"Quite simply, we want to find the birthplace of the solar wind," she said.

Way back in the 1950s, before we had satellites or spacecraft to measure the Sun's properties, Parker predicted the existence of this solar wind. The scientific community was pretty skeptical about this idea—many ridiculed Parker, in fact—until the Mariner 2 mission started measuring the solar wind in 1962.

As the scientific community began to embrace Parker's theory, they wanted to know more about the solar wind, which is such a fundamental constituent of the entire Solar System. Although the solar wind is invisible to the naked eye, when you see an aurora on Earth, that's the solar wind interacting with Earth's magnetosphere in a particularly violent way.

Only it is expensive to build a spacecraft that can get to the Sun. And really difficult, too.

Now, you might naively think that it's the easiest thing in the world to send a spacecraft to the Sun. After all, it's this big and massive object in the sky, and it's got a huge gravitational field. Things should want to go there because of this attraction, and you ought to be able to toss any old thing into the sky, and it will go toward the Sun. The problem is that you don't actually want your spacecraft to fly into the Sun or be going so fast that it passes the Sun and keeps moving. So you've got to have a pretty powerful rocket to get your spacecraft in just the right orbit. //

But you can't get around the fact that to observe the origin of the solar wind, you've got to get inside the corona. Fox explained that it's like trying to understand a forest by looking in from the outside. One actually needs to go into the forest and find a clearing. However, we can't really stay inside the forest very long—because it's on fire.

So, the Parker Solar Probe had to be robust enough to get near the Sun and then back into the coldness of space. Therein lies another challenge. The spacecraft is going from this incredibly hot environment into a cold one and then back again multiple times.

"If you think about just heating and cooling any kind of material, they either go brittle and crumble, or they may go like elastic with a continual change of property," Fox said. "Obviously, with a spacecraft like this, you can't have it making a major property change. You also need something that's lightweight, and you need something that's durable."

The science instruments had to be hardened as well. As the probe flies into the Sun there's an instrument known as a Faraday cup that hangs out to measure ion and electron fluxes from the solar wind. Unique technologies were needed. The cup itself is made from sheets of Titanium-Zirconium-Molybdenum, with a melting point of about 4,260° Fahrenheit (2,349° C). Another challenge came from the electronic wiring, as normal cables would melt. So, a team at the Smithsonian Astrophysical Observatory grew sapphire crystal tubes in which to suspend the wiring, and made the wires from niobium.

These latest findings further support the Hubble Space Telescope's prior expansion rate measurements.

Physicists have been puzzling over conflicting observational results pertaining to the accelerating expansion rate of our Universe—a major discovery recognized by the 2011 Nobel Prize in Physics. New observational data from the James Webb Space Telescope (JWST) has confirmed that prior measurements of distances between nearby stars and galaxies made by the Hubble Space Telescope are not in error, according to a new paper published in The Astrophysical Journal. That means the discrepancy between observation and our current theoretical model of the Universe is more likely to be due to new physics.

As previously reported, the Hubble Constant is a measure of the Universe's expansion expressed in units of kilometers per second per megaparsec (Mpc). So, each second, every megaparsec of the Universe expands by a certain number of kilometers. Another way to think of this is in terms of a relatively stationary object a megaparsec away: Each second, it gets a number of kilometers more distant.

How many kilometers? That's the problem here. There are basically three methods scientists use to measure the Hubble Constant: looking at nearby objects to see how fast they are moving, gravitational waves produced by colliding black holes or neutron stars, and measuring tiny deviations in the afterglow of the Big Bang known as the Cosmic Microwave Background (CMB). However, the various methods have come up with different values. For instance, tracking distant supernovae produced a value of 73 km/s Mpc, while measurements of the CMB using the Planck satellite produced a value of 67 km/s Mpc.

Just last year, researchers made a third independent measure of the Universe's expansion by tracking the behavior of a gravitationally lensed supernova, where the distortion in space-time caused by a massive object acts as a lens to magnify an object in the background. The best fits of those models all ended up slightly below the value of the Hubble Constant derived from the CMB, with the difference being within the statistical error. Values closer to those derived from measurements of other supernovae were a considerably worse fit for the data. The method was new, with considerable uncertainties, but it did provide an independent means of getting at the Hubble Constant.

Observations in the past several years, combined with our past knowledge, basically confirmed we live in a weird and unusual part of the universe. Some of those are supported by fairly hard numbers and others are a bit more vague. The famous Drake equation would need several more factors just to cover all relevant information to explain the lack of spacefaring civilizations.

Here are a few new-ish ones, either newly discovered, or just something we didn’t realize is highly relevant in this context.

1. The Sun is not normal. It’s a type G star, this puts it in a group of stars numbering 7.6% of the Milky way. Of those it’s in the 10% most stable type G stars stars. A stable star is probably necessary for life and the factor for a suitable star is around 0.7% at this point.

2. Plate tectonics. In relatively recent times we came to realize plate tectonics are probably important for life, recycling the crust into the mantle without wrecking havoc on the surface every few million years. Of the planets in the Solar system, only Earth has suitable plate tectonics. We don’t know how common they are in the universe, but 10% is probably generous.

3. Rocky planets are typically larger than Earth, around 1.5 times Earth mass. This is relevant, because at 125% the size of Earth you can’t make an orbital chemical rocket any more. If you want a spacefaring civilization you kind of need that, at least as a stepping stone. Let’s call this one at 10%, it shouldn’t be very far off. //

4. The Solar system itself is highly unusual and will get several points. We have large planets on the outer edges and small planets closer to the star, which is only seen in about 10% of cases. Most star systems have large planets closer to the star and smaller planets outwards.

5. Solar system part two, it is unusual for a solar system to feature both rocky planets and gas gigants. Most have one or the other type of the planet, but not both. Let’s say this is another 10%, it’s probably lower but let’s put it at 10%.

6. Solar system part three, about 85% of star systems have more than one star, 15% have one star. For type G that’s a bit higher, with 56% and we can’t explain this yet. Let’s call this one 50%.

7. Solar system part four, we’re located in an unusually calm part of the galaxy. Most places have been variously zapped with X-ray bursts, supernovae or came across various other types of other cosmic horrors that would have ended any nascent life with prejudice. Let’s put this one at 10% of the galaxy being as calm as our bit, though it could be considerably less.

If you want to count the zeroes, we’re at approximately 1 in 100 billion at this point, certainly below 1 in 10 billion. Milky way has approximately 400 billion stars. Just accounting for these factors, then adding the “chance to develop life” in and some of the other stuff present in the Drake equation, pushes the probability of advanced, spacefaring civilization forming life being present in the Milky Way, to 1 planet or less. It’s probably a lot less, we rounded plenty of those estimates upwards, because it honestly didn’t matter.

Earth is rare. We know enough to state that with some certainty. We don’t know what other solutions to the Fermi paradox are also valid, but we know enough to state Earth and Solar system being total weirdos is one of them. They might well be unique to the Milky Way and possibly even rarer than that, there’s no way to know for sure.

Everything we learn about exoplanets and solar system formation seems to point more and more toward the rarity of our planet. We circle the right sort of star in the Goldilocks part of our galaxy, which is a good galaxy for us. Our planet is in the right place and is the right size. It has this nearly impossibly large moon that helps make large tides that probably had much to do with evolutionary steps that resulted in complex animals. It also stabilized our obliquity. We have plate tectonics and a substantial magnetic field. We had an unlikely asteroid encounter 65 million years ago, exactly when mammals were ready for prime time. Exit dinosaurs stage left. Enter mammals center stage.

We cannot assign exact probabilities to all of the steps, but we can see how unusual and rare our planet really is. There are not trillions of copies in this universe.

Here's the math behind making a star-encompassing megastructure.

In 1960, visionary physicist Freeman Dyson proposed that an advanced alien civilization would someday quit fooling around with kindergarten-level stuff like wind turbines and nuclear reactors and finally go big, completely enclosing their home star to capture as much solar energy as they possibly could. They would then go on to use that enormous amount of energy to mine bitcoin, make funny videos on social media, delve into the deepest mysteries of the Universe, and enjoy the bounties of their energy-rich civilization.

But what if the alien civilization was… us? What if we decided to build a Dyson sphere around our sun? Could we do it? How much energy would it cost us to rearrange our solar system, and how long would it take to get our investment back? Before we put too much thought into whether humanity is capable of this amazing feat, even theoretically, we should decide if it’s worth the effort. Can we actually achieve a net gain in energy by building a Dyson sphere? //

Even if we were to coat the entire surface of the Earth in solar panels, we would still only capture less than a tenth of a billionth of all the energy our sun produces. Most of it just radiates uselessly into empty space. We’ll need to keep that energy from radiating away if we want to achieve Great Galactic Civilization status, so we need to do some slight remodeling. We don’t want just the surface of the Earth to capture solar energy; we want to spread the Earth out to capture more energy. //

For slimmer, meter-thick panels operating at 90 percent efficiency, the game totally changes. At 0.1 AU, the Earth would smear out a third of the sun, and we would get a return on our energy investment in around a year. As for Jupiter, we wouldn’t even have to go to 0.1 AU. At a distance about 30 percent further out than that, we could achieve the unimaginable: completely enclosing our sun. We would recoup our energy cost in only a few hundred years, and we could then possess the entirety of the sun’s output from then on. //

MichalH Smack-Fu Master, in training
4y
62

euknemarchon said:
I don't get it. Why wouldn't you use asteroid material?
The mass of all asteroids amounts to only 3% of the earth's moon. Not worth chasing them down, I'd guess. //

DCStone Ars Tribunus Militum
14y
2,313
"But [Jupiter]’s mostly gas; it only has about five Earth’s worth of rocky material (theoretically—we’re not sure) buried under thousands of kilometers of mostly useless gas. We'd have to unbind the whole dang thing, and then we don’t even get to use most of the mass of the planet."

Hmm. If we can imagine being able to unbind rocky planets, we can also imagine fusing the gas atmosphere of Jupiter to make usable material (think giant colliders). Jupiter has a mass of about 1.9 x 10^27 kg, of which ~5% is rocky core. We'd need to make some assumptions about the energy required to fuse the atmosphere into something usable (silicon and oxygen to make silicates?) and the efficiency of that process. Does it do enough to change the overall calculation though? //

Dark Jaguar Ars Tribunus Angusticlavius
9y
11,066
The bigger issue is the sphere wouldn't be gravitationally locked in place because the sun is cancelling it's own pull in every direction. Heck even Ringworld had to deal with this flaw in the sequel. That's why these days the futurists talking about enclosing the sun recommend "Dyson swarming" instead.

Edit: A little additional note. You can't really get the centrifugal force needed to generate artificial gravity across an entire sphere like you can with a ring. A swarm doesn't negate this. If you orbit fast enough to generate that artificial gravity, you're now leaving the sun behind. Enjoy drifting endlessly! No, rather each of these swarm objects are just going to have to rotate themselves decently fast.

The James Webb Space Telescope is the most powerful telescope ever put into space. As such, its helping usher in a new era of astrophysics. Astronomers can now study farther, earlier galaxies than ever before. //

As they peer into the deep, distant history of the universe, scientists are shocked to find galaxies showed in our cosmic history much sooner than scientists ever expected.

What galaxies forming earlier than scientists thought possible means for physics
Short Wave
What galaxies forming earlier than scientists thought possible means for physics
It's a galactic controversy that has astronomers around the world excited—and puzzled.

So what is it about these galaxies that is getting astronomers worked up? Not only is JWST finding galaxies forming 200-500 million years after the Big Bang, but also that they are bigger and brighter than astronomers expected. //

But much of the modeling astronomers have done up to this point has led them to believe that there wasn't enough time for galaxies to get this massive in so little time. //

In an attempt to explain the shockingly bright, highly structured—and possibly quite massive—galaxies existing so early in the timeline of the universe, a researcher has posited that the universe is roughly twice as old as previously believed. They push the age of the universe from a spry 13.8 billion years old to roughly 26.7 billion years old. //

"I think in science, if you already have a model that's simpler than that, you should stick to it—unless you have extraordinary evidence to do otherwise."

Moreno also cautions people against quickly jumping on this supposition that the universe is twice as old as previously thought. If it were true, scientists would be able to prove it through the direct observation of stars and galaxies that are older than 13.8 billion years old—the current accepted age of the universe.

No such evidence has been found.

They hold the keys to new physics. If only we could understand them.

Somehow, neutrinos went from just another random particle to becoming tiny monsters that require multi-billion-dollar facilities to understand. And there’s just enough mystery surrounding them that we feel compelled to build those facilities since neutrinos might just tear apart the entire particle physics community at the seams.

It started out innocently enough. Nobody asked for or predicted the existence of neutrinos, but there they were in our early particle experiments. Occasionally, heavy atomic nuclei spontaneously—and for no good reason—transform themselves, with either a neutron converting into a proton or vice-versa. As a result of this process, known as beta decay, the nucleus also emits an electron or its antimatter partner, the positron.

There was just one small problem: Nothing added up. The electrons never came out of the nucleus with the same energy; it was a little different every time. Some physicists argued that our conceptions of the conservation of energy only held on average, but that didn’t feel so good to say out loud, so others argued that perhaps there was another, hidden particle participating in the transformations. Something, they argued, had to sap energy away from the electron in a random way to explain this.

Eventually, that little particle got a name, the neutrino, an Italian-ish word meaning “little neutral one.” //

All this is… fine. Aside from the burning mystery of the existence of particle generations in the first place, it would be a bit greedy for one neutrino to participate in all possible reactions. So it has to share the job with two other generations. It seemed odd, but it all worked.

And then we discovered that neutrinos had mass, and the whole thing blew up. //

Nazgutek Ars Scholae Palatinae
23y
866
That was a fun read. I feel like I've climbed a single Dunning-Kruger step and now I feel like I know that I know less about the universe than I did before reading this article! //

NameRedacted Ars Praetorian
7y
445
Subscriptor
karadoc said:
such that relative to you the neutrino's direction of motion would then be reversed (compared to before you overtook it)... so then I'd expect that to be a right-handed neutrino from the point of view of that speedy observer.

I may be very wrong here, but I think that the entire point of chirality is that you can’t just reverse it by changing your perspective.NameRedacted Ars Praetorian
7y
445
Subscriptor

karadoc said:
such that relative to you the neutrino's direction of motion would then be reversed (compared to before you overtook it)... so then I'd expect that to be a right-handed neutrino from the point of view of that speedy observer.

I may be very wrong here, but I think that the entire point of chirality is that you can’t just reverse it by changing your perspective. //

NameRedacted Ars Praetorian
7y
445
Subscriptor
Back when I first graduated with my engineering degree, I really wanted to go back and get a PHD in physics because I loved QM so much.

Every time I read one of these articles, I’m glad I didn’t. Don’t get me wrong, this stuff is exciting: but I don’t think I could handle how much the universe “wants” to perplex us.

I have little doubt that the physics world will need to completely change everything to figure out all four of the big “mysteries”: Neutrinos, Dark Matter, Dark Energy, and the Hubble Constant. I also have little doubt that the solution will be complex, expensive, and be an advancement on the level of QM (I.e. atomic energy and semiconductors).

I hope I’m alive for when it happens, but *$&@ am I ever glad I haven’t spent my career trying to sort it out. //

Simk Smack-Fu Master, in training
4y
56
Subscriptor++
I really enjoyed that article! I'm none the wiser for having read it, but that seems fitting for the subject matter. //

neil_w Ars Praetorian
13y
464

Well, the properties of neutrinos don’t line up like this. They’re weird. When we see an electron-neutrino in an experiment, we’re not seeing a single particle with a single set of properties. Instead we’re seeing a composite particle—a trio of particles that exist in a quantum superposition with each other that all work together to give the appearance of an electron-neutrino.

For a moment I considered just closing the browser tab after reading this paragraph.

This was a very good article, trying to explain the nearly unexplainable. Hat tip to the physicists who are able to grasp it all. //

dmsilev Ars Praefectus
14y
5,375
Subscriptor
The sum of all three neutrino masses cannot be more than around 0.1 eV/c2
The absolute value of the square of the difference between m2 and m1 is 0.000074 eV/c2
The absolute value of the square of the difference between m2 and m3 is 0.00251 eV/c2

One thing which the article didn't mention is that there's an additional question hiding in these constraints. Usually, mass scales with family; the electron is lighter than the muon is lighter than the tau, and similarly for the quarks. We assume that that's the case for neutrinos as well, that m1 (the major constituent of electron neutrinos) is less than m2 is less than m3. That's called the "normal hierarchy" solution. However, the data doesn't prove that. There's also an "inverted hierarchy" fully consistent with the data which swaps the ordering. And we can't tell which one is correct. The only reason for the somewhat prejudicial names "normal" and "inverted" is the sense of elegance that the laws of physics should be somewhat consistent.

Scientists carried out a survey of five million distant solar systems with the help of 'neural network' algorithms and it took an interesting turn when they found nearly 60 stars surrounded by what appeared as "giant alien power plants."

Among the 60 stars, seven of them - which were M-dwarf stars and ranged between 60 per cent and 8 per cent the size of the Sun - were seen releasing high infrared 'heat signatures,' as per the astronomers. //

While these structures are named for Freeman Dyson, a physicist and mathematician who proposed the building of a Dyson sphere to contain and capture all of a star's energy output, the concept actually goes back to a 1937 novel, Star Maker, by author Olaf Stapledon.

But as far as this study actually having detected such structures? Color me skeptical. //

What isn't said is what other explanations might cause these mid-infrared emissions; while I'm a biologist and not a cosmologist, it seems to me that a G-sequence star like our sun, were it to be surrounded by a cloud (or clouds) of gas or dust, may well also emit such an IR signature. And that's a lot more likely than an alien civilization that would by necessity be thousands, or millions of years ahead of us, technologically. //

Cliff-Hanger
3 hours ago
Ward, I'm a little disappointed. Dyson structures mentioned and not one bad pun about vacuum cleaners sucking the energy out of the stars.

Simultaneity Ain't what It Used to Be

One of the most fundamental deductions Albert Einstein made from the finite speed of light in his theory of special relativity is the relativity of simultaneity—because light takes a finite time to traverse a distance in space, it is not possible to define simultaneity with respect to a universal clock shared by all observers. In fact, purely due to their locations in space, two observers may disagree about the order in which two spatially separated events occurred. It is only because the speed of light is so great compared to distances we are familiar with in everyday life that this effect seems unfamiliar to us. Note that the relativity of simultaneity can be purely due to the finite speed of light; while it is usually discussed in conjunction with special relativity and moving observers, it can be observed in situations where none of the other relativistic effects are present. The following animation demonstrates the effect. //

... by extracting transmissions from the LM from those originating in mission control onto separate tracks with the Audacity audio editor, I was then able to time-shift transmissions originating from the Earth by the light delay of 1.2865 seconds to reproduce what Buzz Aldrin and Neil Armstrong heard through their headphones in the cabin of the Eagle lunar module on the surface in Mare Tranquillitatis. During the landing phase, an on-board tape recorder in the lunar module captured the voices of Armstrong and Aldrin even when they were not transmitting on the air to ground link. From this noisy source, I have restored the few remarks by Armstrong which were only heard within the cabin. This is, then, the lunar touchdown as heard by the astronauts who performed it.

Now it's obvious what happened to Armstrong's post-landing transmission! Right before he began the call, Duke's message, sent a second and a quarter earlier, arrived at the Moon. While, from an earthly perspective, this was spoken well before Armstrong said “Houston”, on the Moon this message “stepped on” the start of Armstrong's transmission (especially considering human reaction time), and caused him to pause before continuing with his message. Note also that on the Earth-based recording, Duke's response occurs almost immediately after the end of Armstrong's transmission, but on the Moon, the astronauts had to wait for the pokey photons to make it from the home planet to their high gain antenna on its distant satellite.

There are about 200 billion stars in our Milky Way galaxy. Over the next million years our descendents will spread among the stars in an exponential explosion of life, remaking the galaxy as surely as life has remolded Earth in its own image. //

Imagine the variety of worlds and wealth of living species flourishing upon them! Water worlds, desert planets, mountains that reach above the sky—every habitat imagined in science fiction will become real, and many more yet to spring from the imagination of world-makers born half a million years from now.

Terranova is a highly premature anticipation of this exhilarating milestone in the endless adventure of life and intelligence. Every day around 11 a.m. Universal Time a new planet is created using random parameters, and an image of it, as seen from the bridge from your approaching starship, is produced.

“If they existed, they would be here”, said Fermi. So where are they? Nowhere in evidence. Intelligent beings with technologies advanced millions of years beyond our own, spread to the far ends of the galaxy, should not be difficult to detect. We already possess the means to detect even primitive technological civilisations like our own at a distance of hundreds of light years.

If they existed, they—the first intelligent species to expand outward among the stars—would be here. And since we look around and see nobody but ourselves, then it is only reasonable to conclude, “We are here, so we are them.”

Here are two options for future humans to keep us in the habitable zone.

One last reflection to stress the importance of our Moon, which keeps the tilt of the Earth stable and limits the amount of wobble along the planetary axis. https://www.universetoday.com/164878/we-owe-our-lives-to-the-moon/

With every shift in the tilt, the seasons would radically change. Instead of regular, predictable changes year after year, we would experience ages with endless summers, or ages with violent but short winters, or anything in between. The rhythm of the seasons provides a pulse for life, which has the freedom to grow and evolve without trying to overcome great climactic shifts caused by a changing axis.

Luna acts as a great gravitational counterweight, stabilizing the motion of the Earth. By providing a source of gravity external to our planet, the Earth’s interior is free to shift and reconfigure as it pleases – the Moon steadies our hand and keeps us upright.

Our planet is endowed with extravagantly rich mineral ore deposits. How did we get them and why is it significant? It turns out that the source of these deposits is not indigenous; rather, large asteroid/comet strikes over the past 2 billion years produced Earth’s richest metal ore deposits.