Showing posts with label physics. Show all posts
Showing posts with label physics. Show all posts

Friday, April 15, 2016

Starshot, SETI, and the Universe

We may be within a generation of sending probes on flyby missions to other stars, high-energy jets from several distant galaxies all point in the same direction, and we're learning more about hot super-earths.

That sort of thing fascinates me, your experience may vary.

Meanwhile, SETI researchers will be checking out red dwarfs: which may be more promising places to look for neighbors than we thought.
  1. Breakthrough Initiatives' Starshot Project: Sailing to the Stars
  2. That's Odd: Aligned Galaxy Jets
  3. Too Hot for Air
  4. Still Searching for Neighbors

"...Only Two Possibilities...."



"Thar's only two possibilities: Thar is life out there in the universe which is smarter than we are, or we're the most intelligent life in the universe. Either way, it's a mighty sobering thought."
(Porky Pine, in Walt Kelly's Pogo; via Wikiquote)
I've quoted Kelly's Porky Pine before. It's among the more clear-headed things I've seen written about the possibility that we may have neighbors in this universe. (July 26, 2015; November 7, 2014)

In my considered opinion, there's life elsewhere in the universe: or not. I'd be astounded if there isn't, but right now we don't know.

As I've said before, 'is there life in the universe' isn't quite a new question.

Back in the 13th century, some European scholars had insisted that Earth had to be the only world like ours: because Aristotle said so. That's when the Church stepped in: reminding folks that God's God, and Aristotle's not. (July 31, 2015; June 27, 2014; February 23, 2014)

As it turns out, there are more worlds: some orbiting our star, plus a growing list of planets around other stars.

Aristotle has had a profound influence on Western thought, but he was wrong about our standing on the only world. I've mentioned Anaximander before: but not Democritus. They both thought there could be, and probably were, many worlds. (August 7, 2015)

As it turns out, they were right.

A recent news item involved SETI: Search for Extraterrestrial Intelligence. Maybe you've read why God's decisions don't upset or offend me.

If you have, feel free to skip down to Breakthrough Initiatives' Starshot Project: Sailing to the Stars, which doesn't involve SETI; Still Searching for Neighbors, which does; go for a walk; take a coffee break; whatever.

Order, Beauty, and Opportunities


Still with me? Thanks!

Briefly —

I think that the universe operates according to logical, knowable, physical laws. As a Catholic, I must believe that. (Catechism of the Catholic Church, 299)

I must also believe that this universe is a place of order and beauty, and can learn something about God by studying God's creation: and that studying the universe is okay. We can, using reason, see God's work in the universe. (Catechism, 32, 35-36, 301, 303-306, 311, 1704)

We're told that scientific discoveries are opportunities for greater admiration of God's greatness. (Catechism, 283)

I certainly don't have a problem with that.

1. Breakthrough Initiatives' Starshot Project: Sailing to the Stars



(From Christian Darkin/Science Photo Library, via BBC News, used w/o permission.)
("This generic artist's concept shows how a solar sail might work"
(BBC News))
"Hawking backs interstellar travel project"
Pallab Ghosh, BBC News (April 12, 2016)

"Stephen Hawking is backing a project to send tiny spacecraft to another star system within a generation.

"They would travel trillions of miles; far further than any previous craft.

"A $100m (£70m) research programme to develop the computer chip-sized 'starships' was launched by the billionaire Yuri Milner, supported by Facebook founder Mark Zuckerberg.

"Interstellar travel has long been a dream for many, but significant technological hurdles remain.

"But Prof Hawking told BBC News that fantasy could be realised sooner than we might think.

" 'If we are to survive as a species we must ultimately spread out to the stars,' he said...."
I'm not sure what Hawking meant by "if we are to survive as a species...." He might have meant that we'd die if we don't travel to the stars: or that we'll certainly reach the stars if we survive. Either way, I think he's (almost) right.

In the first case, if we stop trying to find out what's 'out there,' we'll have lost something very basic in our nature. I'll get back to that, later in this post.

In the second case, if we somehow manage to become extinct before reaching the stars — I really do not think that will happen. That's not blind optimism, and I've talked about that before. (December 24, 2015; October 25, 2015)

My attitude about Hawking's statements may be the sort of thing that happens when remarks by a theoretical physicist and cosmologist get nitpicked by a writer and artist. I talked about Hawking's support of a SETI project last year. (July 24, 2015)

Breakthrough Initiative's Starshot is "...aiming to demonstrate proof of concept for light-propelled nanocrafts. These could fly at 20 percent of light speed and capture images of possible planets and other scientific data in our nearest star system, Alpha Centauri, just over 20 years after their launch...." (News, Breakthrough Initiatives)

Starshot: This Just Might Work


Their version of Robert L. Forward's fictional beam-powered propulsion is a bit beyond today's tech: but not by much.

I talked about more-than-a-bit-beyond-today's tech like beamed-core antimatter rocket engine and Forward's gigawatt laser array, week before last. (March 25, 2016)

Current 'light sail' technology, like NanoSail-D — that's a picture of it, unfurled in an Earthside laboratory — might have to be tweaked, but it's been flight-tested.

We may — eventually — build ships with thousand-kilometer-wide sails, pushed by light from massive laser banks, focused through 10-kilometer-wide lenses, as described in Forward's Rocheworld.

Or someone may have worked the bugs out of Alcubierre warp field1 generators by then: leaving the construction of light-sail ships to hobbyists of a later era.

Or we may discover that there's something fundamentally wrong with the math of both approaches: and find another way to travel between stars.

What jumps out at me from Breakthrough Initiatives' Starshot is their proposal of an Earth-based laser array using adaptive optics to focus the beam for comparatively rapid acceleration while the tiny ships are still relatively nearby.

That would eliminate the need to keep a beam focused over 'astronomical' distances.

I'm pretty sure at least some of the small probes would still be working after their three-decade trip to Alpha Centauri.

Voyager 1 and Voyager 2, launched in 1977, are still sending back data: 39 years into their missions.

Just how the Starshot probes would transmit signals back to Earth is — a good question. One approach, I suppose, would be to design them along the lines of Rubenstein's kilobots, so they could assemble themselves into a high-gain antenna when they arrived. (August 22, 2014)

Make that before they arrive. Starshot would be a flyby mission: zipping through the Alpha Centauri system at about 20% speed of light. That's fast enough to make the trip from Earth to our sun in a skosh under 42 minutes.

My guess is that the first interstellar mission, whatever propulsion tech we use, will be a flyby. That's what we've done before, sending probes to other planets. (November 13, 2015: October 30, 2015)

I'm also quite sure that we'll want probes that can slow down and take a look around after they arrive.

Background:

2. That's Odd: Aligned Galaxy Jets



(From Prof Russ Taylor, via Royal Astronomical Society, used w/o permission.)
("An image of the deep radio map covering the ELAIS-N1 region, with aligned galaxy jets. The image on the left has white circles around the aligned galaxies; the image on the right is without the circles."
(Royal Astronomical Society))
"Astronomers in South Africa discover mysterious alignment of black holes"
News & Press, Royal Astronomical Society (April 12, 2016)

"Deep radio imaging by researchers in the University of Cape Town and University of the Western Cape, in South Africa, has revealed that supermassive black holes in a region of the distant universe are all spinning out radio jets in the same direction – most likely a result of primordial mass fluctuations in the early universe. The astronomers publish their results in a new paper in Monthly Notices of the Royal Astronomical Society.

"The new result is the discovery – for the first time – of an alignment of the jets of galaxies over a large volume of space, a finding made possible by a three-year deep radio imaging survey of the radio waves coming from a region called ELAIS-N1 using the Giant Metrewave Radio Telescope (GMRT) in India.

"The jets are produced by the supermassive black holes at the centres of these galaxies, and the only way for this alignment to exist is if supermassive black holes are all spinning in the same direction, says Prof Andrew Russ Taylor, joint UWC/UCT SKA Chair, Director of the recently-launched Inter-University Institute for Data Intensive Astronomy, and principal author of the Monthly Notices study.

" 'Since these black holes don't know about each other, or have any way of exchanging information or influencing each other directly over such vast scales, this spin alignment must have occurred during the formation of the galaxies in the early universe,' he notes.

"This implies that there is a coherent spin in the structure of this volume of space that was formed from the primordial mass fluctuations that seeded the creation of the large-scale structure of the universe...."
We've been learning quite a bit about the "large-scale structure of the universe" lately.

The more up-to-date textbooks mentioned "island universes" when I was in high school. These days they're called galaxies, astronomers have been mapping galactic clusters and superclusters, which form walls and filaments of superclusters.

The universe we're in is huge and almost unimaginably ancient: which gives some folks conniptions. I don't mind a bit, and that's another topic. (September 26, 2014; July 15, 2014)

We've been studying 'light' — microwave frequencies, actually — from the edge of the observable universe, some 46,000,000,000 light years away 'now.' (June 14, 2015)

Those light quanta have been heading our way since this universe cooled down enough to be transparent, some 380,000 years after the Big Bang.

The Big Bang was only 13,798,000,000 years ago, give or take 37,000,000. Light — radiation of any sort that we know of — travels at the speed of light. But the edge of the observable universe is about 46,000,000,000 light years away because this universe is still expanding.

Oddly enough, that expansion is speeding up, and that's yet another topic. (April 17, 2015)

That gets me back to what the Inter-University Institute for Data Intensive Astronomy's Taylor said about "...primordial mass fluctuations that seeded the creation of the large-scale structure of the universe...."

Sort of.

Black Holes and the Universe


We've been learning that big galaxies generally have really big black holes in the middle. Stuff falling toward those black holes forms an accretion disk, sort of a scaled-up version of what forms around new(ish) stars. (November 14, 2014)

That accretion disk spins — like pretty much everything else in this universe, it's a physics thing. Stuff in some accretion disks spins really fast: close to the speed of light.

When that happens, jets of stuff shoot out, parallel to the disk's spin axis. Scientists are still figuring out exactly how that works.

Pierre-Simon Laplace figured that the escape velocity for very massive stars might be greater than the speed of light, John Michell wrote about "dark stars" in 1783.

Karl Schwarzschild worked out the math for what we call the Schwarzschild radius in 1915, David Finkelstein and Charles W. Misner noticed a topological defect in the gravitational metric — that was in 1958.

Don't bother trying to remember all that: there will not be a test on this, not being a teacher any more has advantages, and that's yet again another topic.

Where was I? Primordial mass fluctuations, folks with names like Schwarzschild and Finkelstein, Quantum mechanics. Right.

I've talked about quantum gears and philosophy before: briefly. (September 26, 2014)

The point is that stuff that became those galaxies used to be a lot closer than it is now. That's (probably) why their supermassive black holes spin on pretty much the same axis.

More than you probably need to know about:

3. Too Hot for Air



(From Peter Devine, via BBC News, used w/o permission.)
"Planets stripped bare by host stars"
BBC News (April 11, 2016)

"Astronomers have confirmed the existence of planets that have had their atmospheres stripped away by their host stars.

"Planets with atmospheres that orbit too close to their host stars are bombarded by a torrent of high-energy radiation.

"The gaseous outer layers of these worlds are then stripped away, according to the international team of scientists.

"Their work appears in the journal Nature Communications...."
What's "hot" and what's not depends on context. A pop tune may be "hot," metaphorically speaking, a summer day here in Minnesota can be "hot," literally, compared to our winter weather; and we've been finding quite a few metaphorically and literally "hot" exoplanets.

I've talked about 55 Cancri e and HAT-P-11b before. (February 19, 2016; October 3, 2014)

Scientists had good reason to think that at least some planets orbiting very close to their stars might be more massive than Earth, but with no atmosphere.

Now it looks like at least some of those theories are a pretty good match with reality. That will help us understand how planets and stars form and develop.

None of which will give me brighter, whiter teeth; help me find an exciting, rewarding, career; or win the lottery. But I'm human, and I've been over that before: often. (March 18, 2016; March 3, 2016)

More:

4. Still Searching for Neighbors



(From Seth Shostak, SETI Institute; via Space.com, used w/o permission.)
("The SETI Institute's Allen Telescope Array in Hat Creek, California is now searching 20,000 red dwarf stars for signs of intelligent life."
(Space.com))
"SETI's New Alien Life Hunt Targets 20,000 Small, Dim Stars"
Mike Wall,Space.com (March 31, 2016)

"The search for intelligent aliens has expanded to include thousands of star systems very different from that of Earth.

"Scientists with the SETI (Search for Extraterrestrial Intelligence) Institute in Mountain View, California have just begun a two-year hunt for signs of alien civilizations around 20,000 red dwarfs — stars considerably smaller and dimmer than Earth's sun.

"Red dwarfs are promising targets for SETI scientists. They are the most common stars in the Milky Way, making up about 75 percent of the galaxy's stellar population. And because red dwarfs burn through their fuel slowly, they live a long time; on average, the Milky Way's red dwarfs are billions of years older than the sun, researchers said...."
The Space.com article included an informal, highly-unscientific poll: asking "Do you believe alien life exists elsewhere in the universe?" I was the 55,742th respondent. The results weren't terribly surprising:
  • Yes - We may not have found them yet, but they're out there.
    64% (35902 votes)
  • No - Aliens are just part of science fiction.
    20% (11277 votes)
  • I'm not sure
    15% (8563 votes)
I was in the 15% minority.

"Belief in Extraterrestrial Life:" Certainty, Uncertainty, and Religious Affiliation



(From Survata, used w/o permission.)

My guess is that a Survata poll of Americans, done in 2013 or thereabouts, is a tad more accurate. In that one, roughly a third of American Christians, Jews, Muslims, Hindus, and atheists/agnostics weren't sure about whether we have neighbors.

Interestingly, over half of "other" 'believe in the existence of extraterrestrial life.' That may help explain why some American Christians are adamant that life mustn't exist anywhere except Earth.

Like I said, I'm not sure. We either have neighbors, or we don't. Right now, we don't know, and I'm okay with that.

I hope we do have neighbors. For one thing, it would make this universe seem a bit less empty.

For another, comparing notes with folks who aren't human would be an opportunity to learn how much of 'human nature' comes from being critters with free will and bodies; and how much is strictly "human."

My guess is that we'd learn that a great many of our neighbors are fine folks: but not "human." At all. Which is why I think nearly every SETI effort makes unwarranted assumptions.

Tesla, Pulsars, and "Wow!"


SETI is part of the SETI Institute's name. (www.seti.org)

It's also a generic term, the Search for extraterrestrial intelligence's acronym. Like ancient Romans, Americans use a lot of acronyms, and that's still another topic.

I'll be talking about SETI in general. Current efforts arguably began in 1896, when Nikola Tesla said that he should be able to communicate with Martians with his wireless electrical transmission system.

He thought he had detected Martian signals in 1899, at his Colorado Springs experimental station.

I gather that Tesla's oddly-regular static might have come from Marconi's European radio experiments, static from Jupiter's plasma torus, or something else that wasn't Martians.

Or maybe someone was trying to get a distress call to the nearest rescue station — using badly-damaged equipment.

If that's the case, which I think is extremely unlikely, we'll eventually find them; or the equivalent of a SAR ship is on its way — or was here, and left.

We've had SETI false positives since then, including PSR B1919+21 (1967) and the 1977 "Wow! signal."

I gather that Susan Jocelyn Bell, a graduate student at the time, and Antony Hewish, her thesis supervisor, wanted a reason to not identify the thing as an artificial beacon. They were both professional scientists, and had careers to think of.
"...At this point, Burnell notes of herself and Hewish that 'we did not really believe that we had picked up signals from another civilization, but obviously the idea had crossed our minds and we had no proof that it was an entirely natural radio emission. It is an interesting problem—if one thinks one may have detected life elsewhere in the universe, how does one announce the results responsibly?'..."
(Pulsar, Discovery, Wikipedia)
Later, after more rapidly-pulsing radiation sources showed up in other parts of the sky, they started looking more like a previously-unknown natural phenomenon.

Or maybe a network of navigation beacons. Each one pulsed at a slightly different rate: and much, much faster than a star should be able to.

Eventually we caught one slowing down, and decided that highly magnetized rotating neutron stars were the best explanation for observed data.

I'd love to think that there's a vast civilization using pulsars as a sort of galactic GPS system: but I figure the scientists are right.

The Universe, Life, and Us


Recent (1950-to-current) SETI efforts have tried detecting artificial radio signals from promising sections of the sky, from specific nearby sun-like stars, and now we're trying pretty much the same thing for red dwarf stars.

I don't think the efforts were a waste of time and effort. Folks collected a great deal of data, which should help us understand this universe.

But I'm pretty sure that there's nobody like us within several dozen light years. Whether or not we've got next-door neighbors: is another matter.

Like I've said before, SETI generally makes some whacking great assumptions. (July 24, 2015)

We use modulated radio signals for long-distance communication. We could use off-the-shelf tech to chat with folks on planets circling nearby stars: if they're there, and if they use radio, too. Maybe they do. Then again, maybe not.

Let's assume that there's a planet almost exactly like Earth orbiting Alpha Centauri A, a star that's almost exactly like ours. Almost:
  • Mass 1.100 M☉
  • Radius 1.227 R☉
  • Luminosity 1.519 L☉
    (Source: Wikipedia)
Let's also assume that the Alpha Centauri system is exactly the same age as the Solar System, about 4,540,000,000 years; and that life started on that hypothetical planet when life started here. That's a lot of assumptions.

Two more: let's assume that people (that's one) living on that Earth-analog are almost exactly as 'old' as we are (that's the other).

In other words, that they got started within 1/1000th of their world's age as we did. That's 4,540,000,000 times 0.001 = 4,540,000 years. That's a long time.

Instead, let's assume that they're 1/4,540th Earth's age old: that's 1,000,000 years.

A million years back, we were making almond-shaped stone hand axes.

If that's where our neighbors are at, they probably won't build their first radio for another 999,881 years. (June 19, 2015)

If they started 1/4,540th Earth's age before we did, they were probably using radios when we worked the bugs out of those hand axes: and are currently using whatever we'll invent a million years from now.  (June 19, 2015)

My guess is that talking drums, slit gongs, and the Inmarsat network are the not the ultimate communication technologies. (July 24, 2015)

I also suspect that people aren't necessarily as incurably chatty as we are. (January 15, 2016; July 24, 2015; June 27, 2014)

Maybe we have neighbors who have more in common, psychologically, with cats than chimps. That would go a long way toward explaining why we haven't heard anything so far. (August 2, 2015)

Cats don't have pack or herd behavior. They're smart, and social in their own way: but cats don't "act collectively without centralized direction." (Wikipedia)

This doesn't mean we should give up on looking for neighbors. I think, however, that SETI projects would be well-advised to stop looking for signals from the stars, and start looking for indirect evidence that people are at work.

That'd be something fairly small, and not acting like a natural phenomenon: an infrared source in what looks like empty space, unusual concentrations of one heavy element or molecule, and that gets me back to pulsars. (September 26, 2014)

That's assuming that people always develop and use technology on an increasingly-large scale. Maybe we haven't detected our neighbors because they're all quietly contemplating the suchness of sibilance, itemize the enigmatic, or watching the local equivalent of grass grow.

Reassuringly "Human" — and Otherwise?


Then there's physical appearance. If — and that's a big "if" — we have neighbors, we may learn that that folks who look like Mr. Chuckles there are the most reassuringly 'human' of the lot.

Whatever they look like, and however they think, if we do have neighbors — I'm pretty sure that some folks will be upset, others won't care much one way or the other, and at least one religious order — Jesuits, most likely, or their analog in the nth century — will get to work learning their language.

And that's — you guessed it — another topic. (August 2, 2015; July 18, 2014; June 27, 2014)

Had enough? If not, here's more:
1 I've talked about the Alcubierre metric before. From what I've read, some scientists and mathematicians still say an 'Alcubierre drive' shouldn't work. They could be right.

But I think it's significant that objections to building ships whose engines use the Alubierrie metric have shifted from 'it's impossible' to 'it's impractical' and 'it's dangerous.' About the latter: I'm pretty sure they're right. Any technology, from fire to sewing machines, is dangerous if we're not careful. The trick is being careful.

More of my take on fire and other dangerous technology:
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Friday, March 25, 2016

Reaching for the Stars

Scientists and engineers in BAE Systems' Project Greenglow are trying to control, or sidestep, gravity.

Back on my side of the Atlantic, scientists at NASA's Eagleworks say they've successfully tested prototype RF resonant cavity thrusters and a warp field generator. Other scientists are skeptical. Very skeptical.
  1. Project Greenglow, Gravity, and Dime Store Magnets
  2. The Weird Stuff: EM Drives, Warp Field Generators, and More
Newfangled ideas appeal to some, and upset others. (February 20, 2015; January 9, 2015; July 18, 2014))

Maybe, back in the 'good old days' when fire was the latest thing in high tech, some folks still slept with their backs against a tree, hoping hyenas didn't find them — while congratulating themselves on not being like those fire-making innovators.

The rest of us: well, that's another topic. (May 29, 2015)

Rockets in Space: "Absurd?"


Yes, someone actually opined that rockets won't work in a vacuum:
"JULY 17, 1969: On Jan. 13, 1920, Topics of The Times, an editorial-page feature of The New York Times, dismissed the notion that a rocket could function in a vacuum and commented on the ideas of Robert H. Goddard, the rocket pioneer, as follows: 'That Professor Goddard, with his 'chair' in Clark College and the countenancing of the Smithsonian Institution, does not know the relation of action to reaction, and of the need to have something better than a vacuum against which to react -- to say that would be absurd. Of course he only seems to lack the knowledge ladled out daily in high schools.'

"Further investigation and experimentation have confirmed the findings of Isaac Newton in the 17th century and it is now definitely established that a rocket can function in a vacuum as well as in an atmosphere. The Times regrets the error."
("150th Anniversary: 1851-2001; The Facts That Got Away," Tom Kuntz, The New York Times (November 14, 2001))
Quite a few folks apparently still haven't gotten used to the idea, judging from articles like this:
The first interstellar probes may use rocket engines for propulsion: or not. There are some intriguing — and testable — ideas on the table.

Quotes



(From NASA/Tracy Caldwell Dyson, via Wikimedia Commons, used w/o permission.)
("Self portrait of Tracy Caldwell Dyson in the Cupola module of the International Space Station observing the Earth below during Expedition 24."
(Wikimedia Commons))
"Manned space flight . . . has opened for us thus far only a tiny door for viewing the awesome reaches of space. Our outlook through this peephole at the vast mysteries of the universe only confirms our belief in its creator."
(Wernher von Braun, cited in Awake! magazine (June 22, 1999), via Wikiquote)

"O LORD, our Lord, how awesome is your name through all the earth! You have set your majesty above the heavens!

"When I see your heavens, the work of your fingers, the moon and stars that you set in place -

"What are humans that you are mindful of them, mere mortals that you care for them?

"Yet you have made them little less than a god, crowned them with glory and honor."
(Psalms 8:2-6)

"The heavens declare the glory of God; the sky proclaims its builder's craft."
(Psalms 19:2)

"4 Indeed, before you the whole universe is as a grain from a balance, or a drop of morning dew come down upon the earth.

"But you have mercy on all, because you can do all things; and you overlook the sins of men that they may repent.

"For you love all things that are and loathe nothing that you have made; for what you hated, you would not have fashioned."
(Wisdom 11:22-24)

1. Project Greenglow, Gravity, and Dime Store Magnets



(From BBC News, used w/o permission.)
("Dr Ron Evans, the man behind Project Greenglow"
(BBC News))
"Project Greenglow and the battle with gravity"
BBC News Magazine (March 23, 2016)

"A handful of leftfield scientists have been trying to harness the power of gravity. Welcome to the world of Project Greenglow, writes Nic Young.

"In science there exists a uniquely potent partnership between theory and engineering. It's what's given us atomic energy, the Large Hadron Collider and space-flight, to name a few of the more headline acts.

"The theorists say: 'This is theoretically possible.' The engineers then figure out how to make it work, confident the maths is correct and the theory stands up.

"These camps are not mutually exclusive of course. Theorists understand engineering. Engineers draw on their deep understanding of the theory. It's normally a pretty harmonious, if competitive, relationship...."
This is where I could declare that "tampering with things man was not supposed to know" will lead to something pretty much awful.

But I won't, for reasons that I've said so often that I'm tired of repeating them. For now. ☺ (March 18, 2016; March 11, 2016; March 3, 2016)

Some scientists who say controlling gravity isn't practical, or possible, may simply be repeating what they learned in physics 101.

Most, I suspect, understand what's involved:
"...First of all, there was the big, big problem of scale. As Dr Clifford Johnson from the University of Southern California puts it: 'We tend to think of gravity as very strong - after all it's what binds us to the earth. But actually of all the forces we know in nature, gravity's the weakest.

" 'Let me give you a number. It's 10 to the power 40 times weaker than electromagnetism, that's a one with 40 zeros after it!' It seemed that even if one could manipulate gravity in the lab, there was almost nothing there to create any meaningful effect.

"In short, to alter the gravity of a planet, you need the mass of another planet...."
(BBC News Magazine)
Think about it this way: a dime store magnet weighing an ounce will pull a paper clip up, against the force of Earth's gravity.

Putting numbers on that comparison, one ounce is roughly 0.028 kilograms. Earth's mass is right around 5,900,000,000,000,000,000,000,000 kilograms: which is a good example of why scientists use scientific notation, and that's another topic.

Besides, gravity isn't so much a force as it is an effect of space-time's curvature caused by concentrations of mass-energy. That's what Einstein's general theory of relativity says, anyway, and that's the best explanation we've found so far.

Newton, Phlogiston, the Big Bang, and an Expanding Universe


A century from now, we may have a better explanation for gravity. Speaking of which, Newton's law of universal gravitation isn't "wrong."

It's still a pretty good approximation of the phenomenon: and "still considered accurate enough for most small calculations," as the BBC News article said.

I figure Einstein's theory may hold up longer than Becher's phlogiston combustion theory: which made sense, given what researchers knew in 1667. Unlike phlogiston, however, new data has been supporting general relativity's predictions: for the most part. (April 10, 2015)

We also discovered that this universe is expanding.

A bit later we learned that the data makes more sense if we assume that this universe expanded really fast in the moments after the Big Bang, slowed down abruptly: and that the rate of expansion has been increasing since then. (April 17, 2015; April 10, 2015)

That's — odd — and almost certainly means that we have a great deal left to learn.

To the Stars — Doing the Math



(From Project Greenglow, via BBC News, used w/o permission.)
("One of the original sketches for Project Greenglow"
(BBC News))
"...When, in the late 1980s, the aerospace engineer Dr Ron Evans went to his bosses at BAE Systems and asked if they'd let him attempt some form of gravity control, they should probably have offered him a cup of tea and a lie down. Gravity control was a notion beloved of science fiction writers that every respectable theoretical physicist said was impossible.

"As Evans himself admits, it was a tough sell. 'Let's be clear - there were many people in the company who felt we shouldn't do it because we made aeroplanes and this was highly speculative.' Pushing against gravity with wings and jets was BAE's multi-billion pound business, why dabble in scientific heresy? Because, as Evans puts it: 'The potential was absolutely enormous. It could totally change aerospace.'...

"...In the US, Nasa aerospace engineer Marc Millis began a parallel project - the Breakthrough Physics Propulsion Program. Nasa had committed to getting beyond the solar system within a generation, but knew conventional rockets would never get them there.

"According to Millis: 'If you wanted to go to our nearest neighbouring star, and say you want to do it in 50 years, you're having to go at a tenth of the speed of light. Well, the amount of propellant you'd need for that journey is about the mass of our entire sun. We needed something radically different.' Like Evans, Millis was told: 'To think radical, and think big.'..."
(BBC News Magazine)
Researching this post, I learned that at least one chap believes that human spaceflight is a hoax, "even if rockets actually work in vacuum." In his version of reality, Yuri Gagarin's 1961 Earth orbital flight was "communist propaganda."

Oddly enough, he didn't mention the Illuminati and the shape-shifting space-alien lizard-men who control the world. Allegedly.

Before getting back to interstellar flight, a link to the Lemming's discussion of conspiracies; with tongue firmly in cheek:
Getting back to Marc Millis, the Breakthrough Physics Propulsion program, and big numbers —

Saying that "the amount of propellant you'd need for that journey is about the mass of our entire sun" is a good comparison: or would be, if Marc Millis had described the payload and propulsion system. Maybe he did, and BBC News edited that part out.

I did a little checking — there's a link list of resources at the end of this section — the energy needed to accelerate one ton to one tenth the speed of light is 125 terawatt hours: minimum. Unless the mission is to fly by the destination at that speed, decelerating the mass will take the same energy.

That's a lot of energy: very roughly what everyone on Earth uses in 11 hours, if I did the math right.1

I suspect that Millis had in mind a spacecraft with something like a one ton payload, driven by rockets like the ones we use today.

That gets me to mass ratio, the ratio of a rocket's mass with propellant to its mass empty. Multistage rockets are more efficient, since they drop 'empty' parts along the way.

I agree that "conventional rockets would never get them there." More accurately, a spacecraft like Voyager could reach Alpha Centauri: in about 10,000 years.

I talked about interstellar distances, Guy Ottewell's "THE THOUSAND-YARD MODEL/or, The Earth as a Peppercorn" Solar System model, and Wolf 1061 earlier this month. (March 3, 2016)

By the time we have tech that will stay in working order that long, I strongly suspect that we'll have cut the travel time considerably. (January 15, 2016)

Big, but (Fairly) Conventional: Beamed-Core Antimatter Rockets, Gigawatt Laser Arrays


"Conventional" rockets, using energy released by chemical reactions, aren't the only propulsion tech available today.

NASA's Dawn mission uses NSTAR thrusters, Magnetohydrodynamic rocket engines that are much more efficient than their chemical counterparts. (March 13, 2015)

The faster a rocket's exhaust is, the more efficient it is: so ideally the exhaust velocity would be speed-of-light, hence speculative fiction's 'photon drive.'

A beamed core antimatter rocket isn't quite a photon rocket, but the electrons and positrons in its exhaust would be traveling at just under the speed of light.

We know the physics involved, but building one isn't practical today.

For one thing, antimatter is still hard to contain and expensive to produce.

For another, the positive pion/negative pion to positive muon/negative muon to positron/electron reaction requires a containment structure about 1,871 meters long: 6,138 feet. (October 3, 2014)

That's a small project, compared to some other proposals using today's science.

One of my favorites is Robert Forward's gigawatt laser array powered by solar collectors sharing Mercury's orbit, a planet-size fresnel lens several dozen astronomical units out focusing the beam on a light sail.

The technology involved isn't much more advanced than what we have now, although keeping equipment in good condition that close to our sun would be a challenge. My guess is that the cost is what will keep that proposal on the drawing board — for now.

I suspect something like Forward's laser array could push asteroids and comets out of Earth-impact orbits, and that's yet another topic.

'Photon drives,' light sails, and conventional rockets all use Newton's third law of motion:
Next: unconventional propulsion systems.

2. The Weird Stuff: EM Drives, Warp Field Generators, and More



(From Dr. Harold (Sonny) White, Eagleworks Lab; via NASASpaceFlight.com; used w/o permission.)
(NASA Eagleworks' warp-field interferometer test apparatus.)
"Evaluating NASA’s Futuristic EM Drive"
José Rodal, Ph.D, Jeremiah Mullikin, Noel Munson; NASASpaceFlight.com (April 29, 2015)

"A group at NASA’s Johnson Space Center has successfully tested an electromagnetic (EM) propulsion drive in a vacuum – a major breakthrough for a multi-year international effort comprising several competing research teams. Thrust measurements of the EM Drive defy classical physics' expectations that such a closed (microwave) cavity should be unusable for space propulsion because of the law of conservation of momentum.

"EM Drive:

"Last summer, NASA Eagleworks – an advanced propulsion research group led by Dr. Harold 'Sonny' White at the Johnson Space Center (JSC) – made waves throughout the scientific and technical communities when the group presented their test results on July 28-30, 2014, at the 50th AIAA/ASME/SAE/ASEE Joint Propulsion Conference in Cleveland, Ohio.

"Those results related to experimental testing of an EM Drive – a concept that originated around 2001 when a small UK company, Satellite Propulsion Research Ltd (SPR), under Roger J. Shawyer, started a Research and Development (R&D) program...."
First of all, I am not making this up.

NASA seems to have put warp field research on the back burner: no surprise, considering America's politics and economy, and that's yet again another topic.

Research outlined in this article (not affiliated with NASA, by the way, despite the name) isn't 'tin foil hat' stuff, though. The Alcubierre metric and other ideas may go the way of phlogiston: or not. Right now, we're sorting that out.

Informed speculation by scientists:
- - - and the Dean Drive:
Norman Lomer Dean may or may not have really believed that he'd invented a reactionless drive. However:
"...Dean made several controlled private demonstrations of a number of different devices, however no working models were ever demonstrated publicly or subjected to independent analysis and Dean never presented any rigorous theoretical basis for their operation. Analysts conclude that the motion seen in Dean's device demonstrations was likely reliant on unsymmetrical frictional resistance between the device and the surface on which the device was set, resulting in the device moving in one direction when in operation, driven by the vibrations of the apparatus...."
(Wikipedia)
After Dean's death, folks didn't find any working models, or diagrams, of his 'Dean drive.'

The demonstration models he'd shown had been obviously different from his patents; and those were missing, too. This is the stuff of which conspiracy theories are made: but I figure that efforts to replicate the Dean drive failed because it doesn't work: and never did.

RF resonant cavity thrusters, "EM Drives," sound a bit like the Dean Drive, with one important difference: they can be tested, and apparently work.

I'll get back to that, after a quick — for me — look at the Bussard ramjet, which probably won't work.

'It Looked Good on Paper'



(From DavidSZondy.com, used w/o permission.)
(Bussard fusion ramjet: it looked like a good idea at the time.)

Back in 1960, physicist Robert W. Bussard had what looked like a good idea: the Bussard ramjet. The math was valid, as far as it went; but involved "handling energy in quantities that scientists refer to in technical terms as 'bat guano crazy.'2"

It looked good on paper.

Interstellar space is far from empty. Depending on where you are in our galaxy, there's between 0.0001 and 1,000,000 molecules in each cubic centimeter.

That sounds like a lot, but the best "vacuum" we can get in an Earth-surface lab has about 10,000,000,000 molecules per cubic centimeter: which is another reason why space-based labs make sense, and that's still another topic.

About 99% of the stuff is gas, the other 1% dust. The gas is about 91% hydrogen, 9% helium, plus 0.1% of everything else. Quite a bit of it's ionized; so magnetic fields could, in principle, concentrate the stuff enough for fusion to happen.

That sounds promising, since stars run on hydrogen fusion. On the down side, the proton-proton chain reaction only works for some varieties of hydrogen.

Bussard said that the interstellar medium had enough non-hydrogen/helium to keep the CNO (carbon–nitrogen–oxygen) fusion cycle going.

He may have been right, but a 'small' Bussard ramjet needs an intake several kilometers across. For meaningful payloads, we're talking a scoop tens of thousands of kilometers across.

That picture shows the habitat and fusion engine of a 'Bussard' ship: that part is a few hundred meters long. Fanning out at the right are the "field wires," stretching out thousands of kilometers. Minimum.

Comparison time again: Earth is about 12,750 kilometers across. I'm an American with a nearly-lifelong interest in science and engineering, so I'm used to big numbers: but that's big, even by my standards.

Given time and motivation, humanity may get around to building planet-size structures. My guess is that's a long way off, though.

I won't dismiss the idea, though. Back when the sickle was cutting-edge agricultural technology, my ancestors might have found something like the Antonov An-225 Mriya or MS Oasis of the Seas implausible.

Someone may find a way around the 1985 Zubrin/Andrew analysis of Bussard ramjet technology: but it looks like even if we built a scoop big and light enough, the thrust produced is less than the system's drag:

The EM Drive and Other RF Resonant Cavity Thrusters


Radio frequency (RF) resonant cavity thrusters produce thrust without reaction mass or directional radiation: so they're apparently in violation of the law of conservation of momentum.

That's the principle that total momentum is constant in a closed system. Newton's laws of motion and all that.

Scientists who have been developing hardware to test their theories say RF resonant cavity thrusters conserve momentum: but not the usual way.

NASA's Eagleworks tested EM Drive and Cannae drive devices. They say the things produced thrust: not much, but measurable amounts.

Other scientists say that the results show effects of air currents, don't adequately deal with observational error, or aren't right for other reasons. They could be right.

Scientists who are working on RF resonant cavity thrusters say that they've got solid theory to explain what's happening. They could be right. So far, it's "controversial" in the sense that scientists are dealing with a set of new ideas that don't fit what they learned in high school.

These thrusters send microwaves into an enclosed conical metal chamber with a dielectric resonator at the small end. The idea is that electrical power runs the magnetron, directional thrust gets sent toward the narrow end — where it gets caught, sort of.

This excerpt from a Wikipedia page is a pretty good example of how the research and discussions have been going:
"...Shawyer has self-published theory papers about the EmDrive. These include the fundamental assertion underlying the theory: '[t]his force difference is supported by inspection of the classical Lorentz force equation F = q(E + νB). (1) If ν is replaced with the group velocity νg of the electromagnetic wave, then equation 1 illustrates that if vg1 is greater than vg2, then Fg1 should be expected to be greater than Fg2." This statement makes two assumptions which Shawyer does not substantiate and which may explain the discrepancy between Shawyer's predictions and those of conventional physics. For example he assumes that radiation pressure is the result of the Lorentz force acting on charged particles in the reflecting material. This is analyzed by Rothman and Boughn[32] who point out that the standard theory of radiation pressure is more complicated than the simplified analysis suggests...."
(Theory, RF resonant cavity thruster, Wikipedia)
Maybe these thrusters work because there's a radiation pressure imbalance between the two faces, or because they create a virtual plasma toroid, producing net thrust using magnetohydrodynamic forces acting on quantum vacuum fluctuations.

Or maybe the researchers were detecting pressure from air currents. I don't know.

Complicating matters, RF resonant cavity thrusters have an annoying habit of "dying from internal corona discharges around [their] RF output circulator." ("NASA Emdrive experiments have force measurements while the device is in a hard vacuum," The Next Big Future (February 07, 2015))

Replacing them costs money, so researchers have to wait until there's room in the budget.

That NASASpaceFlight.com article says that the Eagleworks warp-field interferometer produced (very slight) results last year:
"...During the first two weeks of April of this [2015] year, NASA Eagleworks may have finally obtained conclusive results. This time they used a short, cylindrical, aluminum resonant cavity excited at a natural frequency of 1.48 GHz with an input power of 30 Watts.

"This is essentially a pill-box shaped EM Drive, with much higher electric-field intensity, aligned in the axial direction. The interferometer's laser light goes through small holes in the EM Drive.

"Over 27,000 cycles of data (each 1.5 sec cycle energizing the system for 0.75 sec and de-energizing it for 0.75 sec) were averaged to obtain a power spectrum that revealed a signal frequency of 0.65 Hz with amplitude clearly above system noise. Four additional tests were successfully conducted that demonstrated repeatability.

"One possible explanation for the optical path length change is that it is due to refraction of the air. The NASA team examined this possibility and concluded that it is not likely that the measured change is due to transient air heating because the experiment’s visibility threshold is forty times larger than the calculated effect from air considering atmospheric heating...."
(NASASpaceFlight.com)
A next step will be to repeat the steps in a vacuum.

More stuff you may find interesting, or not:

Afterword: "A Planet is the Cradle...."


As I write this, Thursday night is turning into Friday morning. It's Holy Week, tomorrow's a big day, and besides — I need sleep. A brief quote, and I'm done:
"Планета есть колыбель разума, но нельзя вечно жить в колыбели"
"A planet is the cradle of mind, but one cannot live in a cradle forever."
(Konstantin Eduardovich Tsiolkovsky, from a letter written in 1911, via Wikiquote)


More, looking around and looking ahead:
1 The International Energy Agency's estimate of world energy use in 2012 was 104,426 terawatt hours.

2 That gem is from David S. Zondy's excellent website. It's still up and running, but as of March 24, 2016 he has still not been able to fix display issues — not his fault, I think. He and his hosting service had a difference of opinion which ended badly, for him. His content is still available, but I have to highlight text to make it visible. It's worth the effort, I think:
  • "Bussard Ramjet"
    Spaceship, Future Space, Tales of Future Past; DavidSZondy.com
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Friday, August 14, 2015

Neutrinos and a Fading Universe

We knew this universe was fading, but now scientists have a much clearer picture of how fast the lights are going out.

Don't panic, though. There's plenty of time to get groceries, climb the Matterhorn, or whatever you have lined up for today. It looks like the 13,798,000,000 or so years since this universe began haven't even brought us to halftime.

Other scientists are pretty sure they're detecting neutrinos generated inside Earth. "Pretty sure" isn't "really sure," though, so they're still working on that research.
  1. Portrait of a Fading Universe
  2. Hot News from IceCube Neutrino Observatory
Right after a very quick glance at natural philosophy becoming science, I'm going to say why I do not believe that thinking is a sin — again.

You've probably read that sort of thing on this blog before, so skip ahead to Portrait of a Fading Universe, teach yourself origami, read a good book, whatever.

Science and an Odd Notion


"Science," strictly speaking, got started in Europe, as folks there were recovering from the Black Death.

In earlier centuries, folks in the Islamic world had access to ancient Greek texts, and a common language: which made comparing notes a whole lot easier. Europeans were using Latin as a common language until very recently, which is why I studied Latin in high school, and that's another topic.

Alhazen was working on optics, astronomy, mathematics, meteorology, visual perception, and what we recognize as the scientific method about a thousand years ago. Meanwhile in Europe, cathedral schools became universities.

After the Black Death, folks like Nicolas Steno laid the groundwork for today's sciences, and an Irish-born Calvinist said that the universe was created in 4004 BC.

The odd notion that faith and reason, religion and science, are at war got traction during the mid-19th century; Albertus Magnus was canonized and proclaimed a Doctor of the Church in 1931, and made patron saint of natural scientists in 1941.

And that's yet another topic. Topics. (July 15, 2014; July 4, 2014; August 16, 2013)

Thinking is Not a Sin


The "Church of Danae" in Wiley Miller's Non Sequitur comic strip is fictional. The fear that there's something bad about thinking — not so much.

Thinking can get a person into trouble: but so can walking or talking, depending on where a person walks and what's said.

I could 'over-think' a situation, eventually convincing myself that some bizarre product of my imagination was a practical solution.

But in that case my problem wouldn't be thinking too much: it'd be forgetting what's real and what's not.

I'm a Catholic, so I don't have to choose between faith and reason. It's faith and reason. ("Fides et Ratio," John Paul II (September 14, 1998); Catechism of the Catholic Church, 35)

I don't see a point in God giving us brains, and expecting us to not use them. But that's just me, indulging in cracker-barrel philosophy.

Happily, the Church has a growing collection of resources online; so finding what's said about an aspect of our faith is fairly easy. Most of the time.

God created a good, beautiful, and ordered world: and gave us brains. We are rational creatures, using our brains is part of what we do. (Catechism of the Catholic Church, 32, 154-159, 299)

We're created in the image of God. We can, using reason, see God's work in the universe. (Catechism, 35-36, 282-289, 301, 303-306, 311, 341, 1704)

Again: thinking is not a sin, and studying this world is okay. Science and technology, learning about the universe and using that knowledge to develop new tools, is part of being human. (Wisdom 7:17; Catechism, 307, 1730, 2292-2295, 2415-2418)

Since I believe that God creates the universe, and isn't a liar, fearing knowledge of God's creation would be illogical. It's like I said last week: truth cannot contradict truth. I was quoting Pope Leo XIII:
"...God, the Creator and Ruler of all things, is also the Author of the Scriptures - and that therefore nothing can be proved either by physical science or archaeology which can really contradict the Scriptures. ... Even if the difficulty is after all not cleared up and the discrepancy seems to remain, the contest must not be abandoned; truth cannot contradict truth...."
("Providentissimus Deus,"1 Pope Leo XIII (November 18, 1893) [emphasis mine])

1. Portrait of a Fading Universe



(From ICRAR/GAMA and ESO, via BBC News, used w/o permission.)
("These pictures show a single galaxy, imaged at some of the different wavelengths in the GAMA survey"
(BBC News))
"Fading cosmos quantified in 21 colours"
Jonathan Webb, BBC News (August 10, 2015)

"A team of astronomers has published a multi-coloured survey of five chunks of space - and offered the best estimate yet of how fast the Universe is fading.

"They analysed the light from 200,000 galaxies in 21 wavelengths and found that the energy output of the Universe has nearly halved in two billion years.

"This agrees with previous calculations, confirming that the lights are slowly going out right across this spectrum.

"The drop is largely due to the falling rate at which new stars are formed...."
News that the universe is going out isn't surprising. There's only enough stuff left to keep star formation going for maybe another 1,000,000,000,000 to 100,000,000,000,000 years. After that, we'll have few billion years left before the last stars run out of fuel. (July 24, 2015)

That's a lot of time. I've talked about time, perceptions, and all that, before. (August 12, 2015)

Those numbers are very approximate, by the way. These scientists said that it's too early to be very specific. That's not surprising, either.

We didn't confirm that the Andromeda galaxy is another "island universe" until 1920s. Much of what we've learned about the size and age of the universe is new since I was in high school. We have a great deal left to learn. (July 15, 2014; June 14, 2015)

Tightening the Error Bars



(Via ICRAR/GAMA, via BBC News, used w/o permisson.)
("GAMA penetrates into space in five wedge-shaped segments - here compared to the range of other major surveys"
(BBC News))
"...'The data release means that a whole lot more people outside the team are going to be able to jump on the data and do science with it, which is incredibly important,' said Dr Stephen Wilkins of the University of Sussex, another GAMA team member.

"He told BBC News that the strength of GAMA is that it combines so many wavelengths, where previous surveys have concentrated on a few....

"...That means they can look at light from stars that are both young and old, as well as light that has been absorbed and then re-emitted by dust. So the new assessment of the Universe's decline includes information from a huge variety of galaxies, including those hidden behind dust....

"...'It's a new spin, and it completely agrees with the previous results - but it's tightened the error bars as well.'

"Specifically, when the team totted up the total energy output of galaxies at three different ages, they saw a steady slump. In total, from 2.25 billion years ago to 0.75 billion years ago, the Universe's output apparently fell by about 40%...."
(Jonathan Webb, BBC News)
Like I've said before, it's exciting when observation or experiment shows that our assumptions about how the universe works need adjustment. But it's also nice when we learn that our theories are reasonably accurate.

As Dr. Stephen Wilkins said, this study confirmed what scientists had found before: and "tightened the error bars."

Error bars are those little marks you see on some graphs, showing how uncertain the data is. Some uncertainty is inevitable. For example, if the smallest markings on your tape measure are 16ths of an inch, you're not likely to be accurate to within 1/64 of an inch.

GAMA (Galaxy And Mass Assembly) survey data won't make much difference in my everyday life — apart from giving me something to write about. It will keep quite a few scientists busy, though.
"...Dr Aprajita Verma, an astrophysicist at the University of Oxford, said GAMA offered a unique and valuable data set because of its spread of wavelengths.

" 'We know that galaxies can exhibit very different properties if you look at them purely in the visible, compared to other wavelengths,' she told the BBC. 'This study is making a census of their emissions, right the way from the UV through to the sub-millimetre range.'

"Dr Verma was also pleased the wider research community would get its hands on the data. 'It will spawn lots of new studies,' she said."
(Jonathan Webb, BBC News)

2. Hot News from IceCube Neutrino Observatory



(From Sven Lidstrom/ICECUBE/NSF, via BBC News, used w/o permission.)
("The IceCube experiment is located near the South Pole but can "look" both upward and downward"
(BBC News))
"Fastest ever neutrino among slew of fresh findings"
Jonathan Webb, BBC News (August 7, 2015)

"Physicists have unveiled a raft of new findings about neutrinos bombarding the Earth from above, below - and within.

"An experiment built in a vast slab of Antarctic ice has doubled its count of 'cosmic neutrinos' from outer space, by searching for arrivals passing through the planet from the north.

"The same team this week announced the highest-energy neutrino ever detected.

"Meanwhile, a detector in Italy reported the first firm evidence for neutrinos produced beneath the Earth's crust.

"These 'geo-neutrinos' carry much less energy but can inform scientists about the radioactive processes generating heat inside our planet.

"The neutrinos from space, by contrast, offer clues about mysterious, violent sources of radiation beyond our own galaxy...."
I talked about neutrinos back in April. They're the first sort of dark matter scientists identified. We've known about them since 1956. (April 17, 2015)

Known about neutrinos, that is. We've had scientists for about a half-millennium, and natural philosophers for much longer, like I said earlier.

This IceCube data is exciting, because scientists can track the muons: zeroing in on their origin to within a half-degree. As the University of Wisconsin-Madison's Francis Halzen tolkd BBC News, "...this is totally going to change the astronomy we can do."

The "geo-neutrinos" are important, too; for scientists studying Earth's interior. I'll get back to that.

Ernie, Bert, and Tracking Cosmic Neutrinos



(From Nasa-verve, via Wikimedia Commons, used w/o permission.)
(Diagram of IceCube's core, a cubic kilometer holding thousands of sensors, nearly a mile under Antarctic ice.)
"...Neutrinos are subatomic particles with no charge and almost no mass, which very rarely interact with anything. This means they can practically cross the Universe in a straight line, passing through entire planets undeflected - and undetected.

"But the IceCube collaboration has laced a cubic kilometre of ice beneath the South Pole with light sensors, to record the flashes created when a neutrino very occasionally bumps into an atom....

"...In 2013 IceCube announced the first ever detection of neutrinos from outside the Solar System: 28 of the particles were caught moving at energies far beyond the reach of humanity's best particle accelerators. Since then, the count of such 'cosmic neutrinos' has climbed above 50. ..."
(Jonathan Webb, BBC News)
Because neutrinos have no electric charge, magnetism doesn't affect them. They have mass, probably, but it's tiny even compared to other subatomic particles. Gravity affects them, and so does the weak subatomic force, and that's about it.

They're produced during radioactive decay and nuclear reactions, like what happens in our sun's core: and inside our planet.

Saying that neutrinos "...can practically cross the Universe in a straight line..." is accurate, or not: depending on how you define "straight line." Gravity affects neutrinos, which gets me into general relativity, world lines, spacetime topology, and Minkowski diagrams.

I can see why Jonathan Webb wrote "in a straight line."

Scientists named that 2013 IceCube neutrino "Ernie:" and another, spotted at about the same time, "Bert." And who says scientists don't have a sense of humor? (Apathetic Lemming of the North (November 22, 2013))

IceCube's sensors don't actually detect neutrinos. They're sensitive to Cherenkov radiation, that blue glow you'll see in water-cooled nuclear reactor cores.

It's what happens when a charged particle goes through a dielectric medium faster than the speed of light in that medium. The speed of light in a vacuum is higher than in stuff like water or glass, which is why we get refraction.

The last I heard, physicists are still studying Alcubierre's math. It looks like moving part of spacetime through the rest takes a lot less power than originally thought. We're still a long way from a practical warp drive, though. Probably.
Shortly after I'd archived those two documents, NASA went black. It wasn't my fault, and that's several more topics. (September 26, 2014; May 24, 2013; : May 23, 2013May 17, 2013)

Getting back to the IceCube Neutrino Observatory's detector, neutrinos are electrically neutral: so they won't generate Cherenkov radiation.

When a neutrino hits something, which is rarely, it knocks charged leptons loose — electrons, muons, or taus. Those things, the IceCube sensors can detect when they make Cherenkov radiation. The sensors are more sensitive to muon effects, since they make longer tracks.

Meanwhile, on Earth - - -



(From the Borexino Collaborative, via BBC News, used w/o permission.)
("Borexino's detector is filled with a specially made hydrocarbon fluid"
(BBC News))
"...Rather than a slab of ice, the Borexino experiment buried under Gran Sasso in Italy contains 200 tonnes of specialised oil, filling an immense, spherical vat that is similarly studded with light sensors.

"Borexino was built to catch low-energy neutrinos spat out by the nuclear reaction at the heart of the Sun. And it was successful - but the international team has now used seven years' worth of data to look inside the Earth itself.

"Our planet's interior generates vast amounts of heat: about 20 times the combined output of all the world's power stations. Much of it is radioactive heat - but scientists don't know exactly how much.

"'The only way to really understand how much heat comes from radioactivity is to measure the neutrinos coming from inside,' explained Aldo Ianni, a member of the Borexino collaboration.

"Detectors like Borexino or KamLAND in Japan have glimpsed such 'geo-neutrinos' already, along with countless stray neutrinos produced by nuclear power stations right across the globe...."
(Jonathan Webb, BBC News)
KamLAND (Kamioka Liquid Scintillator Antineutrino Detector) is part of the Kamioka_Observatory near Toyama. Like the Borexino installation, the detectors are underground.

That's a diagram of the KamLAND detector, originally from "Results from KamLAND reactor neutrino detection."(2005)

It's full of gripping prose like "...The reactor neutrino anomaly defined as the flux disappearance and spectrum shape
distortion is confirmed at the 99.999995% significance...."

I enjoy reading stuff like that, your experience may vary, and "KamLAND" reminds me of "Samarkand" for some reason: maybe because the names rhyme in my language. Sort of.

Anyway, Samarkand was about halfway along the Silk Road. From around 260 AD to 715 or thereabouts, folks there were Buddhists, Zoroastrians, Hindus, Manicheans, Jews, and Nestorian Christians.

Over in Europe, the Frankish kingdom was conquering folks in what's now France and Germany. Then Samarkand started getting conquered, but not by Franks. By 750, Samarkand stopped changing hands quite so often. There were survivors, happily, but the city just wasn't the same as before.

A few centuries later, Genghis Kahn happened, followed by the Black Death, and I've gotten seriously off-topic.

Where was I? Neutrinos, Italy, Japan, Samarkand, Genghis Kahn, Black Death. Right.

Scientists are pretty sure that they're tracking neutrinos generated by radioactive stuff in Earth's mantle. Dr. Aldo Ianni said that their confidence level is 98%. That's pretty good — but not good enough for this to be an official "discovery." Particle physics researchers have rules.

Those rules say that scientists have to get a 5 sigma confidence level — which does not mean watching five Doctor Who episodes featuring Ood Sigma, and I am not going to wander into that topic.

CERN writing guidelines say that 5 sigma confidence means that there's less than a one in a million chance that a 5-sigma result is wrong. That's very high confidence, indeed.

Borexino, KamLAND — Why Bother?



(From Science Photo Library, via BBC News, used w/o permission.)
("The Borexino experiment's stainless steel sphere is studded with light sensors"
(BBC News))
"...Dr Jeanne Wilson is a particle physicist at Queen Mary University of London who works on the SNO+ neutrino experiment in Canada as well as T2K in Japan. She agreed that the Borexino findings were preliminary but important.

" 'From previous results, we could say with good confidence that we were seeing geo-neutrinos - but the more you detect, the more information you can extract on where they're coming from.

" 'We're getting to the point now where you can start to do these analyses.'

" 'I don't think there's anything in these data that contests the models we currently have for the Earth - but they're proving that we're getting to the point where neutrinos will actually help.' "
(Jonathan Webb, BBC News)
These neutrino studies are pretty close to 'pure science:' research done because we're human, and curious; with no obvious economic benefit.

When or if these scientists demonstrate that the phenomena they're studying really are neutrinos from Earth's mantle, it won't result in new and improved hair care products or guaranteed weight loss results. At least, I'd be more than astounded if that happened.

On the other hand, scientists who study Earth's interior will get a new research tool. Today, Geophysicists measure satellite orbits, Earth's magnetic field, seismic waves, and other phenomena to get an idea of what's going on inside our planet.

I'm pretty sure they'd be happy to have another 'window' to look through. Their research will, quite probably, help us predict earthquakes; and prepare for these events. Maybe neutrino research isn't quite so 'pure' after all. I'm okay with that.

Researching this post, I learned that the Borexino observatory is part of the Supernova Early Warning System. My part of the world gets tornadoes every summer, so I appreciate an early warning system's value. Why we need one for supernovas - - -

Eventually I'm pretty sure we'll have immediately practical reasons for a supernova early warning system. Scientists figure one of those big stellar explosions happens within 33 light years of Earth every quarter-billion years or so: on average.

Right now, though, Betelgeuse is the only star in our part of the galaxy that's likely to become a supernova 'soon:' by cosmic standards. It's likely to become a Type II supernova within the next 1,000,000 years.

I've talked about Betelgeuse, science fiction's early years, and vaguely-related topics in other blogs:
How soon Betelgeuse goes boom depends on how massive it is: and we're still not sure about that. The fireworks start when Betelgeuse finally runs short on usable fuel and starts collapsing.

Current models of what happens then say that when a star's core starts collapsing, it goes fast. The outer part of the core will be falling at about 23% of the speed of light. This heats up the core — and it gets complicated at that point.

Neutrinos are fast and 'slippery' enough to escape the collapsing core: carrying some energy with them; and giving astronomers something to study, when shock fronts of energy and particles reach them. That gets me back to the Supernova Early Warning System.

The idea is that by alerting astronomers early in a supernova's development, they can get a better look at the early stages. I gather that Borexino, Daya Bay, KamLAND, IceCube, LVD, and Super-Kamiokande, are part of the system; and that they haven't spotted anything yet.

Don't worry about Betelgeuse — it's a little under 650 light-years way, close enough to give us a good view, but far enough so that we'll be safe. Supernovae occasionally go off close to home, and that's another topic. (January 16, 2015)

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What's That Doing in a Nice Catholic Blog?

From time to time, a service that I use will display links to - odd - services and retailers.

I block a few of the more obvious dubious advertisers.

For example: psychic anything, numerology, mediums, and related practices are on the no-no list for Catholics. It has to do with the Church's stand on divination. I try to block those ads.

Sometime regrettable advertisements get through, anyway.

Bottom line? What that service displays reflects the local culture's norms, - not Catholic teaching.