Showing posts with label cosmology. Show all posts
Showing posts with label cosmology. 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, 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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Sunday, June 14, 2015

The Universe: a Magnificent Tent

Folks have looked up and been impressed for a long time:
"1 Think! The heavens, even the highest heavens, belong to the LORD, your God, as well as the earth and everything on it."
(Deuteronomy 10:14)
"The heavens declare the glory of God; the sky proclaims its builder's craft."
(Psalms 19:2)
That galaxy is M31, the Andromeda Galaxy. Back when I was in high school, a fair number of books I read called it the "Great Andromeda Nebula." More up-to-date books occasionally called it an "island universe." (September 26, 2014; July 15, 2014)

Abd al-Rahman al-Sufi described M31 as a "little cloud" in "Book of Fixed Stars," more than a thousand years after Deuteronomy and Psalms were written — which is what it looked like before astronomers had telescopes.

The first spyglass was probably made in the Netherlands. A spyglass was good for "seeing faraway things as though nearby:" like the flags of ships. That'd be vital for owners of the Netherlands' merchant fleets.

Then Galileo tweaked spyglass design, made a nice profit selling his spyglasses to merchants, published "Sidereus Nuncius," and was eventually placed under house arrest. I gather it was politics, Galileo's abrasive personality, and folks who mistook poetry for science, that got him in trouble.

Galileo as the shining embodiment of reason, locked in epic struggle against the dark forces of superstition and oppression, makes a good story: but is more myth1 than history. (January 9, 2015; April 25, 2014; October 26, 2009)

From the Dome of Heaven - - -


Years ago, an enthusiastic Christian informed me that our sun goes around Earth, not the other way around — because Joshua 10:12-13 says so. He may have been sincere, but I think he's wrong.

On the other hand, despite what Job 9:6-7 says, I've never known a Christian who said that Earth is flat. (October 3, 2014)

I could be a Christian, following our Lord, if I believed that a solid dome kept the 'ocean of heaven' from flooding the earth I walk on.

But my faith doesn't demand that I ignore what we've learned in the two dozen or so centuries since Mesopotamian culture provided poets with imagery we read in the Old testament.

I'm a Christian and a Catholic, so studying this wonder-filled universe and using what we learn to develop new tools is okay. Science and technology are part of being human. Ethics apply, of course. (Catechism of the Catholic Church, 2293-2295)

Faith isn't reason: but it's reasonable, and certainly not against an honest search for truth. (Catechism, 31-35, 159)

Besides, as I say rather often, scientific discoveries are invitations "to even greater admiration for the greatness of the Creator." (Catechism, 283)

Speaking of which, although size isn't everything — in the two and a half millennia since Job was written, we've learned that our world is huge.

- - - to the Edge of the Observable Universe



(From Andrew Z. Colvin, Licensed under CC BY-SA 3.0, via Wikipedia; used w/o permission.)
(Diagrams of the Virgo Supercluster, left; and Local Group, right.)

Our Milky Way galaxy, labeled — indistinctly at this scale — in red on the left-hand picture, is near the center of the Local Group, a collection of more than 54 galaxies.

Light from the Andromeda Galaxy, that largish white smudge in the Local Group, takes about 2,500,000 years to reach us.

The Local Group is one of more than 100 groups and clusters in the Virgo Supercluster. The Local Group's position in the Virgo Supercluster is labeled in red.

Light takes about 110,000,000 years to cross the Virgo Supercluster. It's one of millions in the observable universe.

Superclusters were the largest known structures in the universe — until we started mapping filaments and walls of superclusters.


(From Andrew Z. Colvin, under Creative Commons Attribution-ShareAlike 3.0 Unported License and the GNU Free Documentation License agreements; via Wikipedia; used w/o permission.)
("A simulated view of the entire observable universe, approximately 93 billion light years (or 28 billion parsecs) in diameter. The scale is such that the fine grains represent collections of large numbers of superclusters. The Virgo Supercluster – home of Milky Way – is marked at the center, but is too small to be seen in the image."
(Andrew Z. Colvin, via Wikipedia))

Scientists have been studying the cosmic microwave background (CMB) radiation: photons released when the universe cooled down and became transparent, some 380,000 years after the Big Bang. It's some 46,000,000,000 light years away "now."

The universe is only 13,798,000,000 years old, give or take 37,000,000, but photons from the CMB started traveling when the universe was a lot smaller. I've mentioned cosmic expansion before. (April 17, 2015)

"...Whatever God Wills...."


Do I approve of the universe being this big, or this old?

My take on that question is — it doesn't matter:
"Our God is in heaven; whatever God wills is done."
(Psalms 115:3)
God's God, I'm not, and I'm quite willing to take reality 'as is.'

"...Though the Heavens Grow Thin like Smoke...."


The last I checked, scientists have quite a few ideas about what will eventually happen to this universe. Since we've only recently started collecting data on dark energy, dark matter, and how reality works on nanoscopic scales, my guess is that today's ideas will soon be heavily revised: or discarded.

I'm not going to make the mistake of confusing poetry and science. (July 18, 2014)

However, I'm quite sure that this universe will change: and eventually end.

That isn't, for me, a particularly comfortable thought: but my preferences won't change reality. Not on a cosmic scale.

The idea that this universe, magnificent as it is, won't last forever is hardly new.

Thousands of years back, it was compared to useful but temporary things like tents and garments:
"He sits enthroned above the vault of the earth, and its inhabitants are like grasshoppers; He stretches out the heavens like a veil, spreads them out like a tent to dwell in."
(Isaiah 40:22)
"3 Raise your eyes to the heavens, and look at the earth below; Though the heavens grow thin like smoke, the earth wears out like a garment and its inhabitants die like flies, My salvation shall remain forever and my justice shall never be dismayed."
(Isaiah 51:6)
"and: 'At the beginning, O Lord, you established the earth, and the heavens are the works of your hands.

"They will perish, but you remain; and they will all grow old like a garment.

"You will roll them up like a cloak, and like a garment they will be changed. But you are the same, and your years will have no end.' "
(Hebrews 1:10-12)
"Then the sky was divided 13 like a torn scroll curling up, and every mountain and island was moved from its place."
(Revelation 6:14)
The end of this universe isn't, I think, the end of reality. And that is another topic. (November 2, 2014)

More opportunities for "greater admiration:"
1 A bit about faith and reason, religion and science, Catholic style:
"...From the beginning of the Age of Enlightenment down to our own day, the Galileo case has been a sort of 'myth', in which the image fabricated out of the events was quite far removed from reality. In this perspective, the Galileo case was the symbol of the Church's supposed rejection of scientific progress, or of 'dogmatic' obscurantism opposed to the free search for truth. This myth has played a considerable cultural role...."
("Faith can never conflict with reason," Pope St. John Paul II (1992) (via Caltech Newman Center))
"Faith and reason are like two wings on which the human spirit rises to the contemplation of truth; and God has placed in the human heart a desire to know the truth—in a word, to know himself—so that, by knowing and loving God, men and women may also come to the fullness of truth about themselves (cf. Ex 33:18; Ps 27:8-9; 63:2-3; Jn 14:8; 1 Jn 3:2)...."
("Fides et Ratio," Pope St. John Paul II, on the relationship between faith and reason (September 14, 1998)
"...Thomas observed that creation is neither a movement nor a mutation. It is instead the foundational and continuing relationship that links the creature to the Creator, for he is the cause of every being and all becoming (cf. Summa Theologiae, I, q.45, a. 3).

"To 'evolve' literally means 'to unroll a scroll', that is, to read a book. The imagery of nature as a book has its roots in Christianity and has been held dear by many scientists. Galileo saw nature as a book whose author is God in the same way that Scripture has God as its author...."
("To participants in the Plenary of the Pontifical Academy of Sciences," Pope Benedict XVI (October 31, 2008))
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Marian Apparition: Champion, Wisconsin

Background:Posts in this blog: In the news:

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.