Star Wars: The Force Awakens – teaser trailer #2

And this one is much more of a tease than the first.

 

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G-HAT (Glimpsing Heat from Alien Technologies)

For those interested in the post about finding advanced civilizations in other galaxies by their heat emissions, Paul Gilster at Centauri Dreams has a write up about the study, including links to additional material as well as the actual paper.

I found that this part clarified the seeming contradiction in the Science Daily article.

The currently reported work tells us that none of the galaxies resolved by WISE in this study contain Type III civilizations that are reprocessing 85 percent or more of the starlight of their galaxy into the mid-infrared. And as mentioned above, out of 100,000 galaxies, only fifty show a mid-infrared signature that could be considered consistent with reprocessing more than 50 percent of the starlight.

These fifty point to the further investigations ahead.

The overall endeavor of which the study is a part appears to be named G-HAT (Glimpsing Heat from Alien Technologies).   Gilster links to a site that looks like it has lots of additional information on it, along with some interesting articles.

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Einstein, Schrodinger, and the reluctance to give up hard determinism

Ethan Siegel on his Starts With a Bang blog has an interesting review of Paul Halpern’s new book on Einstein and Schrodinger, and their refusal to allow the implications of quantum physics to dissuade them from idea that the universe is strictly deterministic.  It’s an interesting post and one that I recommend reading in full.  I may well have to read Halpern’s book.

English: Hydrogen in (3,0,0)-state.

English: Hydrogen in (3,0,0)-state. (Diagram credit: Wikipedia)

The idea that the universe is fully deterministic is one that many people hold on to tightly, even though science has made that view questionable since the 1920s.  Things that happen with a particular quantum particle, such as an electron, can’t be predicted.  We can only assign probabilities to particular outcomes.  It’s only with populations of vast number of those particles that we begin to be able to make predictions.  Determinism appears to be an emergent phenomenon.

Many strict determinists find comfort in the notion that since the uncertainties average out over large enough scales, that we leave quantum uncertainty behind as we go up to the macroscopic scale.  And we do, to some extent.  It’s why we can use innumerable physical laws to make predictions.  But quantum uncertainty does intrude in the macroscopic world.  The very fact that we can do experiments that tell us about it is proof of that.  The question is to what extent it bleeds into macroscopic reality in natural processes.

Even if it only does so in one in a trillion interactions, within the uncertainty involved in any scientific measurement, in complex dynamic systems, chaos theory shows that that one in a trillion outcome can snowball in time to make those complex dynamic systems unpredictable, even in principle.  This means that complex dynamic systems such as the weather, economies, the human mind, and even sufficiently advanced computer systems, may have behavior that will never be predictable, at least not completely.

In my experience, those that do hold on to strict determinism, either don’t understand the implications of quantum mechanics (I won’t accuse them of not understanding quantum mechanics itself since even experts like Richard Feynman never claimed to have that understanding), choose to ignore those implications, or they tightly grasp on to interpretations of quantum mechanics that supposedly preserve determinism, such as the MWI (Many World Interpretation).

While I personally see the MWI as a candidate for reality, I’ve never been particularly impressed by the idea that it preserves determinism.  What does it mean to say that reality is deterministic when everything possible happens, but we still can’t predict what we’ll observe, even in principle, along our subjective timeline?   I’m not convinced that deserves the name “determinism.”  It certainly isn’t very useful for predicting future observations.

Anyway, Siegel’s post is a reminder that we’re all human and fallible, including the geniuses who, sometimes despite themselves, have broken new ground that call into question our most fundamental assumptions about reality.  And that reality itself has no obligation to conform to our most ingrained expectations.

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Searching for advanced civilizations in other galaxies: 50 possible candidates found?

At first, this article seems like a bit of a downer:
Search for advanced civilizations beyond Earth finds nothing obvious in 100,000 galaxies — ScienceDaily.

After searching 100,000 galaxies for signs of highly advanced life, a team of scientists has found no evidence of advanced civilizations there. The idea behind the research is that, if an entire galaxy had been colonized by an advanced spacefaring civilization, the energy produced by that civilization’s technologies would be detectable in mid-infrared wavelengths.

…”Whether an advanced spacefaring civilization uses the large amounts of energy from its galaxy’s stars to power computers, space flight, communication, or something we can’t yet imagine, fundamental thermodynamics tells us that this energy must be radiated away as heat in the mid-infrared wavelengths,” Wright said. “This same basic physics causes your computer to radiate heat while it is turned on.”

Theoretical physicist Freeman Dyson proposed in the 1960s that advanced alien civilizations beyond Earth could be detected by the telltale evidence of their mid-infrared emissions. It was not until space-based telescopes like the WISE satellite that it became possible to make sensitive measurements of this radiation emitted by objects in space.

However, somewhat contradicting the title of the article and its opening passage, we have this snippet:

Wright reports, “We found about 50 galaxies that have unusually high levels of mid-infrared radiation. Our follow-up studies of those galaxies may reveal if the origin of their radiation results from natural astronomical processes, or if it could indicate the presence of a highly advanced civilization.”

I’m not entirely sure what to make of this passage given the apparent contradiction, but it sounds like we have 50 possible candidate galaxies for advanced civilizations.  (Emphasis on the word “possible” here.)

Based on the information the article provides, it seems obvious that the scientists were looking for Type III civilizations on the Kardashev scale.  A Type I civilization has harnessed all of the energy on its native planet.  (We’re not a Type I civilization yet).  A Type II civilization has harnessed all of the energy of its native star, possibly using concepts like Dyson spheres or swarms.  And a Type III civilization will  have harnessed all of the energy in its galaxy, or, at least for purposes of this study, enough to be noticeable across intergalactic distances.

Of course, we have no real idea how possible a Type III civilization actually is.  It would involve engineering on scales that currently seem hard to imagine.  But given enough time (think hundreds of millions of years), there doesn’t seem to be anything in the laws of physics that prevent it.  We also can’t be sure that some observed astronomical phenomena that we’re chalking up to nature might not turn out to be mega-structures created by extraterrestrial intelligence.

But given the age of the universe, and the fact that there’s no evidence of Earth ever having been colonized in its 4.5 billion year history, it seems likely that if there are advanced civilizations out there, they’re too far away to have reached us yet.  50 out of 100,000 galaxies sounds like about the right number.  The nearest advanced civilization may be several hundred million light years away.

Unless they find natural explanations for the high levels of mid-infrared radiation.  Then the closest advanced civilization might might be billions of light years away, or even outside our visible universe.

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Dark energy may be less energetic than previously thought

This is interesting.  Astronomers discovered dark energy, the energy causing the rate of expansion rate of the universe to speed up, by looking at large numbers of Type 1a supernovae.

Image credit: NASA

Image credit: NASA

Type 1a supernovae are white dwarfs (collapsed stars after their fusion has gone out) that explode.  What causes a previously stable white dwarf to explode?  It’s thought that white dwarfs in close orbits with companion stars constantly accrete material from that companion star, gradually adding to the dwarf’s mass.  When its mass reaches a certain threshold (about 1.4 solar masses), it reignites fusion in its dense core, causing it to go supernova.

The idea is that since the white dwarfs will always explode at this threshold, Type 1a supernovae are consistent in their brightness, making them useful for gauging cosmological distances based on their brightness as seen from Earth.  When a Type 1a supernova happens in a galaxy, the distance to that galaxy can be measured fairly accurately.

Using Type 1a supernovae, scientists were able to measure the expansion rate of the universe at various stages in its lifetime, and discovered that the rate of the expansion was accelerating.  The cause of that expansion is unknown, and is referred to as “dark energy.”  Calculations showed that dark energy, whatever it is, makes up almost 70% of the energy in the universe.

Except that since those measurements, Type 1a supernovae have been discovered to not be as consistent as previously thought.  A few years ago, simulations showed that a portion of them may be due to two companion white dwarfs colliding with each other, which means that the originating mass could be as high as 2.76 solar masses.  At the time, I wondered if that would have any implications for measuring the expansion of the universe, but no one seemed to be concerned.

Now though, it appears that the variation ase causing concern:
Accelerating universe? Not so fast — ScienceDaily.

The team, led by UA astronomer Peter A. Milne, discovered that type Ia supernovae, which have been considered so uniform that cosmologists have used them as cosmic “beacons” to plumb the depths of the universe, actually fall into different populations. The findings are analogous to sampling a selection of 100-watt light bulbs at the hardware store and discovering that they vary in brightness.

“We found that the differences are not random, but lead to separating Ia supernovae into two groups, where the group that is in the minority near us are in the majority at large distances — and thus when the universe was younger,” said Milne, an associate astronomer with the UA’s Department of Astronomy and Steward Observatory. “There are different populations out there, and they have not been recognized. The big assumption has been that as you go from near to far, type Ia supernovae are the same. That doesn’t appear to be the case.

…The authors conclude that some of the reported acceleration of the universe can be explained by color differences between the two groups of supernovae, leaving less acceleration than initially reported. This would, in turn, require less dark energy than currently assumed.

“We’re proposing that our data suggest there might be less dark energy than textbook knowledge, but we can’t put a number on it,” Milne said. “Until our paper, the two populations of supernovae were treated as the same population. To get that final answer, you need to do all that work again, separately for the red and for the blue population.”

The article doesn’t go into detail into why these different populations of Type 1a supernovae might be different.  It’s not hard to imagine that they might have slightly different compositions as heavier elements became more pervasive in the universe, and that the collisions I mentioned above may have a slightly higher chance of happening in more recent cosmological times than in more distant ones.

All of this goes to show once again how provisional scientific results always are.  The accelerating expansion of the universe was based on empirical observations, but heavily informed by logical and theoretical calculations.  Anything changing in that framework will change the conclusion.  Of course, no one is saying that dark energy isn’t there, just that it might be less than everyone thought.

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Greg Egan’s Amalgam is close to the most likely interstellar civilization

The other day, I did a post engaging in speculation on, assuming we don’t discover a completely new physics, what I thought an interstellar civilization might look like.  In summary:

  1. Given special relativity, travel faster than the speed of light is impossible.  This has been verified by innumerable experiments, and nothing in nature has been observed to travel faster than light, at least not yet.  There are various notions of ways around this (wormholes, Alcubierre drives, etc) but they are very speculative, requiring the existence of either exotic or cosmological amounts of energy.
  2. Even getting a decent sized spaceship to an appreciable percentage of the speed of light requires appalling amounts of energy.  This has led some scientists to conclude that humans will never explore beyond the solar system.
  3. Sending a small probe (possibly microscopic) is still extremely expensive, but conceivable.
  4. A fleet of small probes could be sent to other stars.  Once there, they could find local raw resources and bootstrap a communication and exploration infrastructure.
  5. These probes could even manufacture copies of themselves to be sent to stars further out.
  6. Over time, an interstellar communications network could be developed, allowing information from throughout the galaxy to be transmitted back to Earth, and AI (artificial intelligence) entities could be sent to the stars to explore.
  7. If mind uploading of some form or another is possible, human minds could be sent to the stars.  If mind uploading is not possible, humanity may have to content itself with the information it receives from its interstellar network.

Wyrd Smythe pointed out to me that this was more or less the vision that Greg Egan has with his Amalgam stories.  Egan is a science fiction author who has explored the concept of mind uploading extensively in his fiction, perhaps more than anyone else so far.  I’d read some of Egan’s work before, but had missed the Amalgam ones.  The Amalgam is the name of the interstellar civilization in the stories.

The Amalgam is introduced in the short story, ‘Riding the Crocodile’, which is available for free on Egan’s web site.  Egan calls the self replicating probes “spores”, which I think is a pretty descriptive label.  He describes the operation of the spores in the opening pages of another story, ‘Glory’, which is also available for free.  If the idea of this type of civilization interests you, I highly recommend both stories.  (I actually had read ‘Glory’ some years ago, but hadn’t realized the Amalgam background to it.)

IncandescenceCoverIf you find yourself with a burning desire to know more about the Aloof, the mysterious alien network in ‘Riding the Crocodile’, then you can read Egan’s novel, ‘Incandescence‘, which gives insights into them.  I should warn you that, while I mostly enjoyed ‘Incandescence’, particularly all of the fascinating ideas that it explores, I often found it tedious.  Most of the novel is about aliens working out the principles of general relativity, which it describes in what I found at times to be excessive detail.  (Egan’s stated attitude is that it’s okay for a fictional book to require you to take notes to keep up.  Not sure how many readers will agree.  I didn’t take notes, but can’t say I always kept up either.)

Egan gives insights into the Aloof, but only indirectly.  The reader has to piece them together from the clues left by the two plot threads.  Many readers finish the book in a state of confusion.  If you do read the book, and find yourself in that state, at least with regards to the Aloof, my recommendation would be to read the opening pages again, up to the point where the Aloof is described, then reread the final page.

While I think Egan’s Amalgam concept has a lot going for it, there are a couple of things about it that I find a bit dubious.  The first is that the society described is very utopic.  Everyone in the Amalgam just gets along with everyone else.  Don’t get me wrong, I’d love to live in such a society.  It follows a common vision in science fiction, of the post-scarcity civilization.  While it’s nice to hope for that, I’m not sure how realistic it is.  Even if your resources span the galaxy, there will still only be so much of those resources, which means economy and conflict will likely still be facts of life.

The other is that the Amalgam is an conglomeration formed from multiple alien species.  I’ve given my reasons why I think that’s unlikely.  Egan does leave room for the possibility that some or all of those other species are “uplifted” ones, species whose intelligence has been boosted by other intelligent species, which I think is more plausible.

Egan’s vision is the closest I’ve seen in science fiction to what I think is the most realistic vision of humanity reaching the stars.  Of course, even the most educated guesses of what reaching the stars will look like is probably as far off as a 15th century monk’s speculation on how humans might reach the moon.  But the Amalgam strikes me as more likely than the common Star Trek like visions.  (Not that I’m not a fan of Star Trek.)

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Neil deGrasse Tyson interviews Elon Musk

Neil deGrasse Tyson interviewed Elon Musk on Tyson’s podcast, StarTalk.  The interview covers a range of topics, and Tyson includes Bill Nye in a running commentary on the interview.  (Chuck Nice is also there to add his usual laughs.)  I found Nye’s take on many things, such as the problems with the idea of colonizing Mars, to be as interesting as Musk’s.

Somewhat related to the previous post, toward the end, they talk about artificial intelligence, and its putative dangers.  Musk pretty much relays what he’s said many times, essentially fearing what AIs might do to us, but I found Nye’s and Tyson’s discussion in the commentary more interesting.  (Neither of them are particularly worried about AIs.)  If you’re interested in the AI part but don’t have time to listen to the whole thing, it starts around the 46 minute mark.

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