Saturday, April 09, 2022

More science please!

It's a busy season. Spring is springing with hot ferocity and I am back to giving speeches and consults about The Future, sometimes boarding airplanes and others via video. Including a coming meeting of NASA's Innovative & Advanced Concepts program - (NIAC).

Which brings us around to science. Yes, amind ructions of war and insurrection and treason against an Enlightenment Experiment that gave us just about everything we have... it's good to pause, now and then, and realize just how fantastic and wonderful this experiment in reason and equality and reasonableness and acceptance of facts has been to us.

YOU are a member of the first civilization that ever did any of the stuff you are about to read about, below. If you quiver with failure of confidence -- or feel tempted by yammerers of gloom -- remember that's what enemies of the Enlightenment want. Snap out of it!

We're wonderful. And we can solve this. Read examples of just how wonderful we are. Starting now.

==A Brighter Future ==

For starters, some fun. As a reminder that the future might… maybe… be better, see again the wonderful Arconic advert using The Jetsons.

And that optimistic future is possible, ironically more than ever in these dolorous and insipidly pessimistic times, as solutions keep rising…. if only we can gather the collective and individual will to use them. As described in Peter Diamandis’s book Abundance; The Future is Better Than You Think. Take this very recent example from Peter’s newsletter:

“This past year, the world’s biggest jeweler Pandora announced it will cease to sell all mined diamonds (which are scarce and fraught with environmental and human rights abuses), and switch exclusively to selling lab-made diamonds, which can be abundant and low cost—produced from water, methane, and electricity.” 

There are few oligarchic-monopolistic conspiracies more evil than the DeBeers diamond cartel. So this is potentially great news, brought to you by advancing technology.

Though Peter starts with the story of aluminum.

== Capsule Updates in Physics ==

From Scientific American: "In a first, scientists have measured the curvature of Spacetime, " revealing subtle changes in gravity's strength. 

Until now, reading the electric field of light has been a challenge because of the high speeds at which light waves oscillates. Current methods can clock electric fields at up to gigahertz frequencies— radio frequency and microwave spectra. A Florida research team has developed the world's first optical oscilloscope:  "Our optical oscilloscope may be able to increase that speed by a factor of about 10,000." Most earlier methods relied upon interference of waves. Could this be important? Are you kidding?

An amazing helium airship that alternates life as dirigible or water ship. Alas, it is missing some important aspects I could explain… As shown in EXISTENCE.

And the latest ‘flying car” is actually a road-ready flying car.  And yes, I have LONG predicted 2024 as the Year of the Flying Car. Well, for the rich. Along certain licensed limo routes. But yeah.

== Paleontology and Archaeology ==

The dinosaurs' last season: Apparently we can now tell pretty precisely when the dinosaur-killing comet or asteroid struck. Not the exact year, but pretty much the exact month! “And it’s looking like life on Earth had a really, really bad June.”

And...? Wonderful finds at Tanis, in the Dakotas, show many creatures exceptionally well-preserved who seem to have died suddenly the very day that asteroid ended the era of the dinosaurs. I look forward to the show! Dinosaurs: The Final Day with Sir David Attenborough will be broadcast on BBC One on 15 April at 18:30 BST. A version has been made for the US science series Nova on the PBS network to be broadcast later in the year.

The oldest human family tree – almost 6000 years old – has been reconstructed from genetic analysis of the occupants of a cairn-tomb in England. Researchers discovered that most of those buried in the tomb were descended from four women who had children with the same man. And so, likely, are many of us.

A recent update on the fascinating Antikythera device.

Helping historians fill in the blanks: DeepMind's new AI helps restore damaged ancient texts and inscriptions, whether written on papyrus, stone, or pottery.

Interesting science on the genes of ancient Egyptians; it will not be welcome in some quarters. They found that the ancient Egyptians were most closely related to the peoples of the Near East, particularly from the Levant.

And related to archaeology… alas… “Japan is scrapping their model 700 Shinkansen Bullet Trains that blow away all passenger trains in our entire country! They’re getting scrapped at Hakata Minami depot and replaced by newer N700A and the latest N700S models. And yes, one can imagine the blowback of ‘national shame(!) if the U.S. or just California were to purchase the old ones, with some refurbishment! 

But here are answers! (1) The deal could include licenses to produce newer models here. But more important: (2) “By installing these proved and utterly safe trains now, we can invest heavily in leapfrogging to the next level. And you need an existing ‘frog’ to leap over!” And finally: (3) Once these are running, millions will say “Oh! I didn’t get it, before. Now I can’t imagine life without these trains.” 

== Business also matters… ==

Steve Jobs said Xerox could have owned computer industry.  A great man (modest too.) and a great loss.  But Xerox was not the worst example, nor Boeing nor Kodak. Want the biggest fail of all? In 1993 - the year that the Mosaic web browser came out and a year before the Bezos family started selling books online - SEARS shut down their established, 150 year mail order catalogue. Yes, that very year. I am sure at some meeting some guy mentioned this Internet thing and was laughed out of the room… even though at the time Sears was a 50% owner of Prodigy, with IBM!

By now Sears would have owned the world. 

Is there a solution to this kind of myopia, that has shrunk the "ROI horizon" of most businesses from 7 years to 3 months, amid a tsunami of criminal 'stock buybacks' that the Greatest Generation wisely banned?

Easy peasy solution. Every undergrad and most grad business majors should be shut down at once. Then allow MBA programs only for those who can show they spent 5 years making a product or delivering a service. And force a harshly winnowed Boeing corporate staff to move back to Seattle.

This is an amazing five-minute video with Steve Jobs--from 1995. The power of visionaries (and competition and innovation and empathy). Read the excellent biography of Steve Jobs by Walter Isaacson. Amazing how he was a very modest fellow.

== Reflections ==

Noted futurist John Smart has finally finished Book 1 of his two book series, The Foresight Guide, which shows how – philosophically and effectively – one can argue for a universe that propels sapient civilizations toward development and light. A passionately intelligent argument for optimism.

A terrific video about the Antikythera device. Alas, like every other discussion of ancient wonders and technologies, not one person discussed the real question... which is why such marvelous methods were lost! 

You know my answer. Secrecy.

There’s a mythology that all the tricks of construction used in the Parthenon were cleverly calculated de novo, when in fact it benefitted from lessons learned across 300 years of lesser works. Likewise, the Antikythera machine blatantly was not the first. There had to have been at least a century of buildup and trials and we never heard of it because of … you know.

== H. G. Welles on… E.T. ==

“We can conceive vaguely of silicon playing the part of carbon, sulphur taking on the role of oxygen, and so forth, in compounds which, at a different tempo under pressures and temperatures beyond our earthly ken, may sustain processes of movement and metabolism with the accompaniment of some sort of consciousness, and even of individuation and reproduction. We can play with such ideas and evoke if we like a Gamma life, a Delta life, and so on through the whole Greek alphabet. 

"We can guess indeed at subconscious and superconscious aspects to every material phenomenon. But all such exercises strain the meaning of the word life towards the breaking-point, and we glance at them only to explain that here we restrict our use of the word life to its common everyday significance of the individualized, reproductive, spontaneously, stirring and metabolic beings about us.”

So said the mighty co-inventor of science fiction, almost a century ago. A fascinating read, as he spoke of the ‘likelihood’ of oceans on Venus and canals on Mars. Yet, he also quotes a noted astronomer’s opinion that star-warmed ocean-bearing worlds must be rare in the cosmos.

Well, at the time, James Jeans and others deemed planets to be rare, making the chances for life limited. (That us the core premise behind E.E. Doc Smith's Lensmen saga.) We now know better. Still, as Wells put it…

“It is limited as yet, but it is still premature of us to define its final limitations. It seems that life must once have begun, but no properly informed man can say with absolute conviction that it will ever end.”

Excepted from: The Science of Life, H.G. Wells, Julian S. Huxley, G. P. Wells, 1929

== A contest re the Fermi Paradox! ==

Finally....  So how many various ‘answers’ to the Question of the Great Silence – or Fermi Paradox – have appeared in music? And sure, in film?

One of you (Talin) suggested a contest  for folks to chime in – under comments. 


 David Bowie has one ("He'd like to come and meet us, but he thinks he'd blow our minds")

- The Carpenters ("Calling occupants of interplanetary craft")

- Jefferson Starship's fun and inventive... but ultimately very nasty and churlish... song “Hijack.”

- Hank Green: "Fermi Paradox."

Have fun in our lively comment community, below, taking a break from international madness.


Unknown said...

The Carpenters track was a cover version; the original was from the band, Klaatu.

Don Gisselbeck said...

The premise of an infinite Diety means that not only is the sparrow's fall noticed but last Sunday's exquisite powder run was preserved in all its glorious detail. It also could mean those brutally tortured lives are somehow redeemed. We approach this as critters fixated on status, power, control, being right, being acknowledged to be right,and wanting everything to be fixed now. The Diety, if such exists, is obviously not like that.
(300 meters vertical, untouched on perfect wind packed powder with just enough challenging turns to keep me honest.)

DP said...

For mind blowing science I'd like to recommend the "Cool Worlds" YouTube channel by Dr. David Kipping.

In particular I would recommend his proposed Halo Drive, wherein a starship the size of a planet could be propelled to relativistic speeds by means of a hand-held laser pointer and a sufficiently large black hole rotating at nearly the speed of light.

Which is what a black hole does, because the stars that collapse into black holes always have some kind of spin to begin with and spin faster and faster as they get smaller and smaller due to conservation of angular momentum (like an Olympic figure skater who pulls her arms in and spins faster). In fact, they spin nearly as fast as the speed of light:

Which results in frame dragging of space time in the region around the spinning black hole. Space-time itself gets warped and resembles water spinning down a sink's drain pipe.

So, take your hand-held laser pointer (only make it computer held for sufficient accuracy) and point to a region just outside the black hole's event horizon and the laser beam orbits around the black hole and emerges on the other side and heads back towards your spacecraft. The encircling laser beam forms a “halo” around the black hole, hence the name of the drive system.

The action is similar to what happens when one of our space probes (like Voyager) get a gravity assist from a close encounter to a planet (like Jupiter) and gets a "free lunch" increase from the planet's gravity (not really free of course as Jupiter loses a tiny, tiny bit of momentum that gets transferred to Voyager - but it is "free" from Voyager's POV).

Laser light however cannot go any faster than light. So instead of gaining speed it gains energy (blue shifting as it does). Send a few joules of energy around a massive enough spinning black hole (or binary black holes orbiting each other) and you get billions of joules coming back at you from the other side of the black hole.

The momentum of this powerful laser beam can propel your laser sail craft to 20% of c or more. There could be up to a billion blackholes in the Milky Way. Engage the Halo Drive at the right location to propel your craft to another black hole where the Halo Drive can be used again, this time to slow the space craft down. When you have mapped the locations and movements of black holes throughout the galaxy you can use the Halo Drive to create an interstellar railroad to any location in the Milky Way.

We still have to get to a convenient nearby black hole. The video mentions that statically the closest blackhole could be about 40 light years away (though there is probably a much higher density of black holes near the galactic center with fewer out here in the spiral arms). Getting to the black hole would require other means (laser light sail powered by a Dyson Swarm of solar powered satellites around the sun seems to be the most practical – a larger version of Project Starshot) to get you there.

Then take your laser light pointer out of your pocket and start cruising the galaxy.

scidata said...

There is now a one word response to criticisms of overly-fanciful computer dreams: Antikythera.

DP said...

And it turns out the black holes are perhaps the best places in the galaxy to colonize.

So, when you are done with “Cool Worlds” I strongly recommend Isaac Arthur’s “SFIA” YouTube channel, like the one where he talks about colonizing black holes:

Because the same trick used by the Halo Drive (or by simply dropping something into the black hole can be used by a civilization constructed on habitats or rings orbiting the blackhole at a safe distance. Unlimited, nearly infinite and essentially free energy for trillions of years. A black hole civilization could survive long after the last star has burned out.

And of course could also be turned into the largest possible bomb we could build.

So, I have two questions for those who are better read and more intelligent than myself:

1. Does stealing energy from a black hole with a Halo Drive cause it shrink/evaporate and thus allow us to tame them and manage them long term, or does it just make them spin slower (and what happens to a spinning black hole when it finally stops spinning)?

2. Are there any SF space operas focused on black hole civilizations using black holes for propulsion and energy?

David Brin said...

DP thanks for that interesting scifi riff on Black Holes. Truly fun! And that was an excellent article about why black holes appear to spin so fast - via conservation of angular momentum - that the edges of their ergosphere’s may approach the speed of light.
Alas there are some problems with using the method you describe.
1. A full 180 degree bend is really hard.

2. The gravitational slingshot is generally an effect of a 3 body system. Jupiter is robbed of a bit of its ORBITAL momentum, around the sun. It its just you and a black hole, I believe the BH will suck away as you leave, any energy you got by falling.

David Brin said...

In my Uplift Storm Trilogy I portray elder races seeking 'tides' and eventually black holes.

DP said...

The biggest problem I see is all of the crap in the black hole's accretion disk scattering the laser beam.

Also the return beam is going to pack a punch. The resultant acceleration my be on the order of 100s of gs - which turns the crew into meat jam.

All of the above an be engineered (super intelligent AI for aiming the laser, shooting just above the black hole's equator and avoiding the accretion sic and calculating the resultant spiraling exit of the laser beam, slowly deploy the sail while the beam is on the allow from more gradual acceleration, etc.)

However, in principle, there doesn't seem to be anything wrong with the approach.

David Brin said...

Except that, as I said, when the beam is climbing back OUT of the gravity well, it gives up much of the energy that it gained when falling IN. Except for that small thing.

Cesar A. Santos said...

I am not very optimistic. The silence seems to indicate that A) Civilization is very rare; B) They kill themselves long before going spaceworthy; or C) There is something out there killing everybody.

The silence can be terrifying.

David Brin said...

Cesar the space of potential Fermi/GreatSilence theories is rather larger than three.

Though my #1 is that humans may bge exceptionally smart and even wise.

Larry Hart said...

Dr Brin:

Except that, as I said, when the beam is climbing back OUT of the gravity well, it gives up much of the energy that it gained when falling IN. Except for that small thing.

I always used to wonder what the benefit of the slingshot effect was for just that reason. I thought that whatever speed you picked up falling toward Jupiter would be lost climbing back out. I was once told that the point was that you go down with a lot more weight of fuel than you come back up with. I never heard the bit about Jupiter losing angular momentum before.

In my Uplift Storm Trilogy I portray elder races seeking 'tides' and eventually black holes.

The comment below contains spoilers for the Uplift series. I can't say what I want to say without giving away a big secret. Caveat emptor.


In a very weird way, that jibed with Dave Sim's unique worldview, which I was reading in Cerebus at the same time I was reading those novels of yours. Sim thought that the tendency of humans to entangle their lives with groups of others led to their souls being weighed down with each other in the afterlife. He thought all of the molecules circulating up and down inside of the sun were trapped souls trying to escape and being pulled back down by gravity. In his view, the best thing to do in life is to avoid entanglements so as to fly freely through space as a disembodied soul.

While it sounds crazy, I kind of knew in a way that many other readers might not just why the location of Streaker's discovery of the progenitors' ship was so controversial as to set off a galactic war. Because the whole of the society of the five galaxies was geared toward the idea that the goal of individauals and species was to migrate toward higher and higher concentrations of matter--deeper and deeper into gravity wells. And yet, the progenetors were found in the Shallow Cluster, some of the flattest space available. Apparently, they purposely avoided the deep gravity wells that everyone else thought were the best places to be.

As I say, in a strange way, this resonated with Dave Sim's idea at the time that while everyone else wanted to marry, reproduce, and combine into social groups, he thought we were all being fooled into doing those things, and that the best thing to do was distance oneself from it all.

Jon S. said...

Doesn't a spacecraft using a gravity slingshot also apply its own thrust while departing? Kind of hard for a beam of light to do that.

David Brin said...

LH asks an important question. Gravity slingshots rely on 2 things.

You fall towards Jupiter speeding up, pass it very fast and then leave uphill. But because you gained speed, Jupiter has less TIME to slow you down before you are beyond hard reach. Hence you keep some of the speed gain. This is NOT true for a laser beam, which travels the same speed going toward and away from a BH.

2. That's speed. VELOCITY is directional. If you did this passing in FRONT of Jupiter's orbital mostion, you are flung retrograde to that motion and hence lose orbital velocity relative to the sun. In fact, this is still an important way to send probes TO the sun!

V'ger and Cassini etc dived BEHIND Jupiter, exiting FORWARD. This is the best way to get a head start entering Jovian orbit or else getting flung outward to zip through the solar system.

Yes Jon S the effect can be magnified with impulsive corrections.


Sim sounds a lot like Yoda and twice as mystical and just plain ornery nuts.

Yes to your Streaker speculation, though.

Andy said...

A couple songs spring to mind for the "Fermi Paradox in music" contest. I suppose they are both in the ecological collapse category.

No Place Like Home by Devo

In the bigger scheme of things
We haven't been around here more than a moment.

And yet too many, it seems,
Believe we are creating a brand new world around us.
We are creating a brand new world without us.

Maybe it really is okay.
Although we're digging our own graves at this moment.
If we should all just disappear
The skies and waters will clear in a world without us

And there's no place like home.
There's no place like home.
There's no place like home
To return to.

We push against the rest of life
As if we can survive without the world around us.

Big Momma Gonna Whip Us Good by The Features

See the weatherman scratch his head
See the animals on the run
See computers try to calculate
The damage that we have done
See the scientists try to figure out
If we can over come

Big Mama's gonna whip us good
Big Mama's gonna whip us good
(Oh no, Oh no, Oh no)
Big Mama's gonna whip us good
Big Mama's gonna whip us good
(Oh no, Oh no, Oh no)
Cause we never, ever, never, ever do
What we should

DP said...

AFAIK Kipping's "Halo Drive" paper has been peer reviewed and can be found here:

His original paper focused on binary black holes orbiting each other (because the "math was easier") which would seem to address your concerns. The use of frame dragging by a single spinning black hole is someone else's idea (AFAIK, it has not been peer reviewed).

As you say 180 degrees is very hard to achieve, and it requires a laser hugging the event horizon so that it is likely to be scattered by all of the material in the accretion disc.

As an engineer, not a scientist, my first instinct is to tinker with the proposal to make it work.

Suppose we modify the Halo Drive by separating the laser pointer from the space craft and aim it at a location outside of the accretion disc. Instead of rounding the black hole a full 180 degrees the laser beam is still bent (say 90 degrees?) to a point where the space ship is ready to receive its accumulated energy.

Scattering by the accretion disk is avoided and the problem of too much energy and too great an acceleration can be avoided. In fact, the separated laser can operate continuously providing steady amounts of lower energy for smooth acceleration that doesn't squash the crew. In fact, the laser can be left in permanent orbit around the black hole to to service multiple space ships.

Maybe the space ship can only go a mere 5% to 10% of the speed of light, but this arrangement seems to solve a lot of other problems.

DP said...

Actually his paper addresses both of our concerns by assuming them away:

A second effect ignored is the energy to overcome the gravitational potential energy of the binary in order to escape the system. Tacitly, it was assumed that the velocities achieved far exceed the escape velocity from the initial standoff distance. Requiring ∆E of Equation (50) to be much greater than the gravitational potential energy of a binary where M2 = qM, one may show that where on the second line, right hand bracket has been Taylor expanded to first-order as well as assuming q ∼ 1. For low βBH, such as βBH = 0.05, this requires a large stand-off distance of a couple of thousand Schwarzschild radii. In the mildly relativistic scenario of βBH = 0.2, standoff distances greater than around a hundred Schwarzschild radii would make the gravitational potential energy factor much smaller than the gained energy. Nevertheless, it could be worthwhile to include this generally small contribution in future work.

(Hence his use of of orbiting binary black holes)

A third assumption is that the circumbinary environment is devoid of opaque material that would lead to beam losses. For example, an accretion disk around the black hole would certainly make it a sub-optimal target for a halo drive. Accordingly, if one requires compact binaries for relativistic acceleration, the other component would need to be another black hole or neutron star to avoid mass transfers forming a disk.

(Orbiting binaries could prevent the accretion disk from forming between them)

Larry Hart said...

Dr Brin:

Sim sounds a lot like Yoda and twice as mystical and just plain ornery nuts.

Dave was always an iconoclast who had no trouble believing that he was right and eight billion people were wrong about something. But the mystical thing started when he read the Bible intending to parody the writing style in his comic, and instead literally fell in love with Scripture. From then on, his only concern in life was making sure to be on God's team.

Yes to your Streaker speculation, though.

Then I wonder if the progenitors would have purposely misled all of their successor species into following a course they knew to be detrimental, or if that was some sort of heresy which had evolved long after the progenitors had vanished.

Or had the distinction even occurred to the author of the series?

scidata said...

There's a lot of consternation about the increasing cloud of satellites in orbit. Everything from launches to communications to astronomy is being threatened. The usual (gov't) solution is to restrain the pace of satellite deployment. I won't even get into SpaceX vs FAA (you wouldn't like me when I'm angry :). Few ever suggest deeper space deployment/bases (duh, the moon??). Thinking small is so much more expensive in the long run. Sometimes I suspect that's the real motivation, and I'm no anti-nannystate red-tape-o-phobe (I do want my food/water/air inspected).

Meanwhile giant rocks and GRBs with our name on them lurk in the darkness, let alone internal threats that tick away like clocks. I'm sure foot-dragging bean-counters are somewhere on the Fermi list. The JWST, even without doing much astronomy yet, is showing just how fast we can move the ball if we use the entire field.

David Brin said...

Scidata the fragility of Earth orbit is a concern... infact it focuses the 1st chapter of EXISTENCE. See

There are signs of progress. Like having the LEO comms swarms like starlink occupy very low orbits and equipping them with deployable spools of drag tether, to cheaply de orbit. I am more concerned with psycho leaders of rival despotic nations deciding "WTF! Let's bring the tample down with us!"

DP separating the source laser and using a binary system SEEM to address a number of objections. But at that point we get into the math weeds beyond my pay grade. I will say that flickers from such things near BH binaries might be worth looking for...

...otoh that arrangement is REALLY specialized. Hard to imagine a situation where your ship is alread next to a BH binary from which it then needs such a boost. Unless your aim all along was to leave the galaxy.

Star_Dragon said...

A lot of you seem to be thinking of gravity in practically purely Newtonian terms. I don't know the tensor math required to know the exact details, but in General Relativity the gravitational field near rotating objects gets twisted somewhat, from the spacetime literally being rotated. As a result, gravitational potential doesn't quite exist, due to a path-dependence that doesn't exist in Newtonian gravity or near non-rotating masses. In other words, the gravitational field is non-conservative.

There's a couple of problems with using lasers in that manner: gravitational defocusing and the fact that the energy increase manifests through blueshift instead of new photons. Gamma rays are hard to catch, requiring a lot of extra mass.

If you take the black hole with you, these become lesser concerns, since there's far less distance for dispersion. Of course, this requires a micro black hole for portability, which means that Hawking Radiation is significant, so extracting rotational kinetic energy isn't needed, as you've got a mass-to-energy converter of sorts.
Still, using intense charged particle beams, it becomes possible to pump and extract rotational kinetic energy using the Penrose Process, with careful aiming. Up to 29% of the hole's mass-energy can be stored this way. Furthermore, the rotating hole has a magnetic field so long as it maintains a static charge(it's literally an electromagnet), allowing magnetic manipulation.

Don Gisselbeck said...

There's a sci-fi story somewhere which has the Canadians stopping a US-USSR nuclear exchange by launching debris into space with a-bombs in deep holes in the ground. The tactic of course makes low earth orbits impossible.

David Brin said...

I prefer the gravitational propulsion system from EARTH... gravity lasers!

Unknown said...

Fermi filters and the arts - I think Tom Lehrer has it covered with "We'll all go together when we go".

Stardrives - I think R. Bretnor's idea of planting some female spacewarping plants in the bow of your spaceship and some males in the stern (and away you go!) is the best idea I've seen so far, though it's going to take some advanced botany to get it working.


One of my college best friends got deeply into Cerebus, and I rode along for a while, but right around the time HIV started hitting American culture I noticed that Dave Sim began edging into paranoia. Not sure if there is a link there.

For a long time, though, the aardvark was worth a read.


P.S. in my high school years, interstellar ramscoops were the cool new idea. And if you discount friction, they're still great!

Alfred Differ said...

I think some of y'all worry too much about the commercial 'debris' problem in low orbit. Set aside the psycho leader problem a moment and try a thought experiment.

Two alt.timelines for Earth. One has 10,000 commercial satellites in low orbits all trying to avoid each other. The other has 1000.

1) In which timeline will private money get deployed to work the problem of debris removal? Maybe both… so ask yourself which is likely to get MORE private money deployed as well.

2) In which timeline are regulators likely to understand what can and can't be done? I'm not talking about the physics. I'm talking about engineering expertise. In which timeline are regulators best informed and best able to be (actually) helpful?

3) In which timeline are astronomers most likely to get cis-lunar telescopes in the next generation above the satellite swarms?

Please allow for both timelines to have courts that take cases involving liability for damages one party does to another.

Please allow for both timelines to have insurance underwriters be called upon to absorb the risks, thus demand payments from the insured parties.

Please also allow for many of the interested parties to use arbitration systems that bypass courts. Not everyone, but at least some. This will most likely happen if they use the same insurer/underwriter.

Alfred Differ said...


Some of us are honest-to-goodness physicists. I've been out of academia awhile, but not so long as to lose it. 8)

1) Slingshot works about the same way whether Newtonian or GR. It's a three-body effect where the small BB steals energy-momentum from one of the larger bodies.

2) Thou shalt not violate continuity laws. (Conservation laws with current flows if you prefer a 3D perspective.) Any attempt to violate them implies asymmetries in the cosmos. Claim that and the (huge) burden of proof rests upon you.

3) Torsion looks 'magnetic' in the sense of a 'velocity' dependence for forces, but in GR… gravity is fictitious through and through.

4) Actual magnetism is not torsion. It's a perspective illusion occurring when an observer moves relative to an electric charge. From a 4D perspective, the electric and magnetic fields are components of an antisymmetric tensor (a bivector if you prefer geometric algebras) and the perspective illusion vanishes.

5) There is a way to get GR results to first order without curvature if you treat energy/momentum as the 'charge' for gravity instead of scalar mass. Newtonian gravity falls out of that as the v<<c limit.

6) Lasers are something else again. Very quantum. The existence of an exchange boson at a particular energy/momentum alters the likelihood of further bosons popping out of the field at the same value. It's all there in the acronym. LASER. "light amplification by stimulated emission of radiation". Cascade.

I don't put much thought into these things for space travel except… occasionally… [l]asers in different parts of the E&M spectrum.

We've only recently opened windows on the gravity wave spectrum with new detectors, so I expect some time will pass before engineers do something cute with what we are learning. It took us a while to turn E&M parlor tricks into something useful too, so I can wait.

gerold said...

Another Fermi Paradox hypothesis: I read a paper many years ago (can't remember the author now) who suggested the bottleneck to intelligence was the transition to multicellular life.

The emergence of life was quick. Almost as soon as the seas stopped boiling. But the Cambrian Explosion was just 500 million years ago. That means the earth was already 4 billion years old, and that is close to the total viability window for our system.

Increased luminosity of the sun means our planet will undergo runaway Venus-type heating within, what, a few hundred million years? At least absent Gaia-sustaining countermeasures. We also depend on continued plate tectonics and planetary dynamo to avoid a Mars-type loss of atmosphere and loss of element-recycling. Not to mention sterilizing radiation; not sure if that would be lethal but it would get harsh.

The argument was that we squeaked in under the deadline, which means most other planets with similarly benign environments would not. If our transition to multicellular life was freakishly fast, then the galaxy could be full of planets loaded with bacteria but intelligence would be extremely rare. Plausible at least.

duncan cairncross said...

Re - space junk

The latest satellites like the Starlink all have their own orbital control and disposal systems

As far as the rest is concerned space is HUGE

If we just look at LEO from say 300 km to 400 km altitude that is 50,000 million cubic kilometers
So if we had 50,000,000,000 "bits of junk" at 10 grams each that would be 500,000 tons of material and would end up with one "bit" per cubic kilometer

scidata said...

We only have a single example of the evolution of complex life. It just seems improbable that in general, RNA/DNA, proteins, catalysts, and hundreds of biochemical building blocks all happen in a flash (immediately and repeatedly in Earth's case), while 'ingestion but not digestion' of mitochondria takes billions of years. As I often say when discussing the Fermi paradox, we're missing something. Not unlike the Information paradox and black holes that took so long to figure out (if we even did).

We live in a universe where events happen such as three solar masses of matter being converted to energy in one great blast (the first GW event we detected). And even more spectacular, some clumps of cells know things like that.

duncan cairncross said...


I agree with that idea - we had a planet with lots of shallow water stirred by winds and tides this gave a huge amount of early life busy beevering away evolving for billions of years

If we had not had the impact that caused the moon then we would have had oceans hundreds of km deep and at best 1/100,000th the amount of life

Which would then take 100,000 times as long???

Tony Fisk said...

@gerrold multi-cellular life (aka eukaryotes) took over a billion years to develop. That's a substantial fraction of the existence of the Universe, so it definitely has grounds for being a filter.

A couple of science items:
Here's a shock wave in a dust cloud extending several million light years. A scale model of the Milky Way is provided for comparison. Are you there?

Good news on the climate front?
Seems like the time it takes for the atmosphere to respond to changes good and bad is measured in years, not decades. That means (i) we can control things more readily(?), and (ii) keeping people's minds on a generational task is less daunting.

Peter said...

A few years ago I was watching some videos at NIAC for Scientists making presentations when afterwards someone in the audience started asking questions. Pointed questions. Paraphrased: "Did your experiment actually show measurable movement?" The scientist was a little defensive. But the voice of the questioner sounded familiar. Suddenly, I knew who it was. You see, I watched quite a few YouTube interviews of him. Yes, it was a Dr. Brin sighting in the wild! Hehe.

David Brin said...

Heh Peter. Yeah I am the gadfly advisor at NIAC I'll announce that symposium for September, this summer.

Tony etc. Yes Multicellularity is a major time step. But there's also a glass ceiling of intelligence that gets bumped against by dolphins, apes, sea lions, elephants and many others.

David Brin said...

Ilithi Dragon.... Happy Submarine day!

Alfred Differ said...


Way, way back when I was first learning this stuff, I heard the 'improbable argument' for abiogensis and glossed over it figuring some future generation would hit on an idea that might be plausible. Planetary probes reported back and atmospheres simulated in bottles and zapped produced goo that was promising, but it's easy to generate plasmas too. 8)

Many years later I finally tripped across entropic arguments and my jaw hit the floor. They actually had an answer for what life is. A 'system' that steals Gibbs free energy to reduce entropy in one place and increase heat and entropy elsewhere. Biospheres are efficient dissipators of energy gradients.

Neat? Just neat? Nope. If we think about it that way, life pretty much has to happen wherever it is possible for molecules to self-organize to BE that more efficient system. On earth we find criminals by following the money. On other planets, we'll find life by finding the energy gradients and looking for entropy flows.

It was another paper on relative entropy costs for various molecules that clinched it for me. Any molecule that moves a bit of entropy is more likely to form in near equilibrium conditions over one that moves a lot because more free energy has to be handled for the big one. Turns out RNA is a lot cheaper that way than DNA. However, once RNA is around, the order encoded in it can be captured and storied as DNA by stealing a bit more free energy. Baby steps that occur when favored by natural selection

Eukaryotes are typically bigger than prokaryotes. They have to steal a lot of free energy to create internal structures that wraps around so many things. What drove that to be an advantage? Better flagellae? Sex? Something justified the costs. 'Natural selection' and 'least action' principles have a lot in common, but the later one ties directly to gradients.

As I often say when discussing the Fermi paradox, we're missing something.

My personal suspicion is an energy gradient large enough to justify large numbers of eukaryotes just wasn't there until about 2GY ago. Prokaryotes invented a form of photosynthesis and started dumping O2 into the air rusting the world. To do that, cyanobacteria developed internal sheathing we see more in eukaryotes. It's not hard to see why if you find the energy gradients (streaming sunlight) and follow the entropy (products of photosynthesis). Internal structure separates components making photosynthesis a bit more efficient much like what separates C3 and C4 plants techniques today.

My personal suspicion is atmospheric O2 created another gradient. Eukaryotes rose to feed upon it. They made no real sense before that.

gerold said...

Duncan: our moon is certainly a prime suspect for accelerating our evolution. I guess it would mostly be a factor in the early days and the development of dna.

Scidata and Tony: ingestion without digestion (emergence of eukaryotes) was certainly a major step and could be another filter. That was something like 2.7 billion years ago though; perhaps a a more improbable hurdle was multicellular life, which is more recent.

The goldilocks window is going to slam shut in what, another 500 million? The Cambrian Explosion was about 500 million years ago, so it was toward the end of the liquid ocean period.

Maybe we have an unlikely combination of the big moon stirring the early seas and then two low-probability events in eukaryotic cells and multicellularity?

My theory for the multicellular trigger: a Snowball Earth period nearly covered the ocean surface, and when greenhouse warming melted it algae took off in a population explosion. This made filter-feeding suddenly very profitable, and opportunity knocked the sponge to the top of the food chain. You can put a sponge in a blender and convert it back to a bunch of individual cells, but calmer waters allow them to self-assemble back into a sponge. And they filter algae like crazy.

Paradoctor said...

scidata: Ingestion but not digestion of mitochondria has another name: parasitism. 'Symbiote' is a euphemism for 'parasite that negotiated a deal'. Which says to me that those boring giga-years were far from stressless.

Multicellular life emerged from the iceball-Earth phase, which came near to sterilizing the planet. That's a Fermi filter right there. I speculate that for a biosphere to evolve smart critters, it has to pass through at least one perils-of-Pauline moment.

Larry Hart said...

As with Bernie Sanders before him, Trump is becoming "Not Trumpy enough for Trumpers".

Emphasis mine.

Moving along, the biggest Trump news of the weekend was not his poorly attended rally, but his decision to give his endorsement to Mehmet Oz (R) in the Pennsylvania U.S. Senate race. Trump looks at Oz and, in many ways, sees himself: Penn alum, reality TV star, good at parting fools from their money. The former president cares relatively little about the person's policy positions, since he himself cares relatively little about policy. The problem is that Trump's base actually does care about policy, and they were hopping mad that The Donald endorsed a "closet liberal" who has, in the past, supported Roe v. Wade, restrictions on the Second Amendment and, worst of all... Obamacare. Probably best to just burn Oz at the stake right now and get it over with. Some Trumpers are saying that Trump apparently doesn't understand what Trumpism is really about. But perhaps it is actually the Trumpers who don't actually understand what Trumpism is about.

David Brin said...

Alfred that was a very cogent description of how living systems bestride gradients of free energy and use them to create islands of low entropy by exporting more energy toward the black of space. (And hence the core reason why the Greenhouse Effect is inherently lethal to a planet skating so close to the inner edge of our CUZ Glodilocks Zone.)

That fundamental of fairly steep energy gradients has a lesson for human culture and especially economics. Bureaucrats can either ease that flow or else just insert themselves along the gradient as parasites do in Nature, andf the effect is to FLATTEN the gradients and make them less healthy.

The worst parasites in economics are the stock market guys etc who chant that their commissions and fees and endless micro-churning transactions performs a sacred service of ‘finding the correct price.’ A rationalization of profound stupidity that is never justified and (even worse). never challenged! The whole idea of markets is that buyer and seller are SUPPOSED TO disagree about the true price! That’s what makes a steep enough gradient for a living system (economy.) The equities guys are (mostly) like parasites in the skin & guts of wildebeets and lions, sucking away most of the free energy value the scraggly creatures get from grazing & hunting.

I have never been a huge fan of the Big Moon hypothesis, perhaps because it suggests a rather sparse universe. More likely is Water Worlds that have much less land area and hence mostly smart water dwellers, not hands-and-fire guys.

But the oxygenization delay is one I find compelling. Not only the time it took to develop oxygen generation but also the fact that most of that oxygen got sucked up by iron for another billion years and THEN the oxygenization reduced greenhouse so much that Earth turned iceball. In other words, there were phases that help explain why metazoans were delayed till the iceball ended.

scidata said...

The discussion of gradients, entropy, cosmological and geological history, evolution, and even economics is a wonderful privilege for me to simply read let alone partake in. That plus spending a lot of time with young North Americans lately (weddings) have greatly increased my optimism for the continuation of the enlightenment experiment.

However, I still battle with romanticism, conspiracy theories, and plain illogic outside of CB, not to mention my own ponderous shortcomings. A common rhetorical refrain is, "it is exceedingly unlikely [in general] that...", quickly followed by, "but it happened [once], therefore case closed". The legendary 'suck and blow' gambit. Reason is sleight-of-hand swapped for observation in a graceful gloss-over to justify a non sequitur. Often works with people, but try that poo with a HAL9000 and you're liable to get airlocked.

200 billion trillion stars, each with an average of 1.6 planets within 10au*. We have direct (though incomplete) knowledge of one star, one planet, and one nascent technological species. We are (almost) blind, in a dark room, searching for a black cat, who may have long ago wandered off. Every proposed Fermi explanation should begin with that preamble. Many of them should end right there too. This is not an attack on the importance of, or rumination on, the Fermi paradox, but on angels-on-the-head-of-a-pin debate. Lord knows there's been too much of that since 2016. BTW nihilists LOVE the Fermi Paradox. As always, Calculemus!

* Ignoring space rocks, moons, rogue planets, black holes, dark matter, dark energy, multiverse, alternate time lines, time travel, parts of Florida, and other stuff I know little or nothing about (one cannot make a list of things that would not occur to them).

Alan Brooks said...

“...with a HAL9000 and you’re liable to get airlocked.”

Memes get inserted in someone’s head and are as persistent as bio-viruses. A few days ago an educated friend went into a long rant about Fauci being a “horrible Monster”, and “lib’rals are ruining America, and the New World order is....”
Straight out of Pat Robertson. Persuasive friends [frenemies] around such people fill their heads with these notions.
Have to be really careful now in talking and writing; several minutes ago I replied to a FB friend concerning the prospect of ibogaine legalization. He said that even the Taliban is more receptive to legalization than the US. I joked how the Taliban are great people to party with as long as someone continually looks over their shoulders, to see if the Taliban hosts are in a bad mood. Immediately I was banned from FB for 24 hours plus no placing adverts for 30 days—and a list of possible infractions was provided.
Obviously, FB is merely being extra-cautious; now it strongly appears one must rigorously practice self-censorship.

David Brin said...

Alan B... one of the great values of the Wager Gambit is that it doesn't have to be hostile. It can instead be a friendly mind bomb, if you say,

"I value our friendship too much for a fight. But let me know if you are ever willing (man enought? Implied) to put major stakes cash wagers on any of the hot air crap you have yammered. Remember, if you do find one you are willing to back up, I get another of your assertions and we take both before a neutral panel of retired, senior military officers.

"I'm not gonna belabor the point. But whenever you repeat these crazy things and memes that make you feel all righteous, consider - 'would I actually bet that's based on facts?'"

Alfred Differ said...

try that poo with a HAL9000 and you're liable to get airlocked


That's just too much fun not to re-use somewhere.


If I thought I'd live long enough to collect, I'd wager that the fraction of stars with planets that have life is around 0.99... with small qualifications.

Spectral Type F7 or cooler.
Still on the Main Sequence.
Moons around giant planets count as planets.

I'd also wager most of them will be roofed worlds with the equivalent of microbes feed of seafloor vents. Once those worlds get a chance to cool, it all dies but likely in a frozen state that would recover if a gradient reappeared.


I remember science fiction stories from when I was young postulating rare water. Turns out it's all over the place out there. I'd wager a later generation will realize that about the tiniest forms of life.

Stories of aliens showing up and taking a dump that brings a world to life will transform into "Already happened everywhere."

Star_Dragon said...

@Alfred Differ,

I was speaking as a (just barely) honest-to-goodness physicist.

1. Cool beans. 3-body slingshot isn't being debated. Everyone agrees that it works. I'm responding to skepticism about the 2-body slingshot, and the Penrose Process in particular.

2. NOT my claim. Friction is another nonconservative force, that conserves energy and momentum like GR. Nonconservative force != force which violates conservation of energy, even if all of the latter are also the former. I assume that you've gone through first year of graduate school? If so, look up the mathematical definition of potential.

3. 4. Not quite sure what you're arguing against, but the one thing in my post it might have anything to do with is me explaining that Kerr-Newmann black holes have a magnetic field, and why they do. To put it in your terms, any observer is moving relative to the charge in a charged rotating black hole.

5. And what's that got to do with the price of tea in China? Even ignoring that it's an approximation, velocities get quite close to the speed of light near black holes, although I don't know if the approximation is conservative or if it predicts any framedragging at relativistic velocities.
6. Yes, and that's the problem with using a laser to tap a Kerr (or Kerr-Newmann) black hole, unless you're trying to do some kind of gravity pump. Blueshifting a laser beam isn't light amplification(it doesn't make any new photons), but it's what can be done by gravity alone.

7. I sort-of agree, in that I think that it'll be at least centuries, if ever, before we're able to use such gravity tech for anything beyond sensing mass, although mass sensors are actually quite useful in many applications these days.

I just remembered the first known example of these nonconservative(remember, this term doesn't mean that anything isn't conserved in the entire system, any more than a braking car violates momentum and energy conservation) means that effects: Mercury's orbital precession.

gerold said...

Life as a free-energy pirate is certainly the right way to look at it, even for plants. All of the free energy coming from the sun will eventually be re-radiated out to space whether life is here or not, but we are able to siphon a small percentage (like a hillbilly living next to an oil pipeline) for our own uses. We're not actually creating more entropy, just segregating it.

I like to look at the biosphere in terms of a thermodynamic heat engine. We have a hot source at about 5000 K and a cold sink at 3 K, and our energy processing takes place around 300 K. From the Carnot equation we can calculate the maximum possible energy extractable from such a heat engine. Life pinches a tiny fraction of that.

A nice heat engine analogy to the evolution of complexity comes from the technological evolution of the steam engine. The early Newcomen engines used atmospheric pressure to drive the power stroke; extremely inefficient:

James Watt came up with a better design. Instead of cooling the entire cylinder to condense the steam, Watt added a dedicated condenser. This new component greatly increased efficiency and power.

A slight increase in complexity made the machine work a lot better. This is analogous to the evolution of the eukaryotes. By adding new organelles they became better at gathering or generating resources.

At the moment humans are the culmination of complexity increase. It's made us very good at resource gathering. Maybe too good.

The next level will be transcendent AI. Maybe they'll be too good as well, but I find all the hand-wringing about terminators a bit tiresome. Cooperation beats competition, and human-AI competition doesn't make sense. There just isn't much overlap in our ecological niche. And our own stupidity means we have more to gain from them as partners than what we fear from them as rivals.

David Brin said...

Interesting that as recently as THE EXPANSE, SF authors though you must import water to Ceres. Cripes, that is what the place is made of!

gerold said...

DB: yes - much as I enjoyed Independence Day, the idea of aliens coming to earth to steal our water was an eye roller. Reminded me of a 50's scifi where they came for our women. Puh'leeze.

David Brin said...

Well, it was "V" where they came for the water... and that dumb Tom Cruse "Oblivion." In ID they came to render us extinct.

Alfred Differ said...


I was speaking as a (just barely) honest-to-goodness physicist.

Excellent! Gloves off then! (bwa-ha-ha!)

Regarding #2, I believe you now. You know how it goes with a lot of people we meet on the inter-tubes. Something for nothing is so typical in their reasoning. I made it through grad school and even taught a while, so I'm turning off any assumptions I make about you from now on. 8)

So… I won't argue against pretty much anything from Penrose… except maybe on one point that I think all the GR folks gloss over. (Yes. That makes me sound like a quack.) Curvature is A way to get gravity, but not the only way. There are options with classical field theory that produce Mercury's orbit precession without curvature. These options were difficult to explore way back when because the math tools weren't up to the task. Some are now. *

As for using any of this, we are like Benjamin Franklin's peers trying to contemplate lasers. We've got a bit of work to do in securing our mental models before I'd put effort into stuff further out.

* Mercury's precession and bending starlight around the sun can be done with a non-curvature theory. Make the 'charge' the energy-momentum of the test particle and use two Clifford Algebras to keep track of the geometry so one doesn't mix motion and property incorrectly. A theory that looks much like E&M emerges from a continuity principle.

… and yes. We get wave propagation for the usual reasons.

My personal opinion is we are jumping the gun when thinking about use of tightly curved spaces to do much of anything except exercise wonderful imaginations.

Alfred Differ said...

Heh. My effort to suspend disbelief for Oblivion had them arriving to render us extinct... oh and while we are here... we'll take your biosphere to make sure.

Still... taking water off Earth has to be one of the sillier ways to acquire it unless you are stuck on the surface like us.

As for taking the women... uh... here's some water.

(People like peril stories. They don't have to make sense.)

duncan cairncross said...

I agree with Alfred

I suspect there will be billions of planets with life - the Ice roofed worlds

But they will each have only a tiny tiny fraction of the amount of life that Earth has and as a result the universe is not old enough for them to produce complex life

Star_Dragon said...

@Alfred Differ.

Thank you, and I know how it is, regarding such people met online. I've met a lot of them, and at least thought that I was seeing a number of such here in these blog comments. While the word "nonconservative" is not only technically(the best kind of?) correct, but in many ways the best and most obvious term for force fields with curls and other forces which cannot be determined by taking the gradient of a scalar field, it's way too easy to interpret as "does not conserve something".

Regarding non-curvature theories of gravity:
-Plain old Newtonian gravity, especially using the optional interpretation of it deflecting light(at half the amount correctly predicted by GR), was used in the 18th century to correctly predict a startling number of features of black holes, including getting the Schwarzschild radius correct, and that the Dark Stars might emit radiation anyway(by a mechanism wildly different than Hawking Radiation).
-Any theory correctly predicting the precession of Mercury's orbit is nonconservative.

The two things tightly curved spaces are good for right now are the occasional black hole lensing event and modeling gravity wave generation from black hole mergers(maybe not useful in and of itself, but it allows us to test the predictions, which is better than any string theory so far).

Jon S. said...

Honestly, I could have believed that motivation in Independence Day. I thought it was pretty obvious that the invaders weren't the ones who developed their technology - they were too incurious, and never even sought out ways to use it more efficiently. (Why would a truly advanced race need to hijack the target world's satellite communications to coordinate a planetary attack? Why are the control surfaces for a species with such a different set of grasping limbs even comprehensible to humans, much less usable by us? And let's not even get into how you can hack into an alien computer system with a Macbook and control it, when it's difficult to get Apple systems to interface with Windows systems here on Earth - unless that's meant to tell us something about Steve Wozniak's origins...) So I could have bought them as being too stupid to know how to find water ice in space. (Kind of like the Kazon in Star Trek: Voyager, who were one of the few races the Borg declined to assimilate as they would bring no value whatsoever to the Collective. They were a former enslaved species that overthrew their slavers, then started cruising around in stolen starships trying to act like they controlled the quadrant.)

Larry Hart said...

Jon S:

Honestly, I could have believed that motivation in Independence Day.

I only saw it once, back when it was new, but wasn't the core moment of Independence Day the scene where they were trying to negotiate a truce with the aliens, and when they asked "What do you want?", the answer was something like, "We want you dead"?

I took that as a ham-handed argument against diplomacy and in favor of military spending.

But maybe that's just me. :)

Star_Dragon said...

@Jon S.
A lot of that actually makes sense. It's clearly explained in the movie that we didn't develop all of our own technology, but reverse-engineered most of our electronic technology from the Roswell crash, over decades. In other words, hacking into the alien technology with a Macbook is hacking into alien technology with the same kind of alien technology. It's also made clear that we're not too incurious, and have sought ways to not only use it more efficiently, but new uses for it, including suborning someone else's hardware. Them being able to hack our commsats doesn't make sense considering that, as such would have many security measures, which the aliens have never considered, because they never had the concept of doing things that security measures protect against.

David Brin said...



Howard Brazee said...

I'm a strong believer that the exceptions should be very rare tactical reasons for the state keeping secrets from its bosses, the people.