Archive for the 'Astronomy' Category

Nov 05 2018

Oumuamua and the Alien Hypothesis

Published by under Astronomy

One year ago, in October 2017, astronomers detected the first confirmed interstellar visitor to our solar system – an asteroid dubbed Oumuamua. The name is Hawaiian for “scout”, as if the asteroid is a messenger from a distant system. A Hawaiian name was chose because the object was discovered by the Panoramic Survey Telescope and Rapid Response System-1 (Pan-STARRS-1) in Hawaii. Determining that Oumuamua was an interstellar object was not difficult – the determination was based on its trajectory. It was traveling really fast, too fast for any object originating from our own system. It’s velocity would also take it out of our system – it was moving too fast to be captured by the gravity of our sun.

All of that is cool enough, but astronomers carefully analysing the trajectory of Oumuamua discovered (and published their findings in June 2018) that its acceleration could not be explained entirely by gravity. Some force was pushing, ever-so-slightly, on the object. This acceleration could be explained by outgassing, if there were any volatiles on Oumuamua that were heating up as it got closer to the sun. These gases would be like tiny rocket engines. Observations of the object did not detect any comet-like tail, which is why it was thought to be an asteroid. But if this new observation were correct, then it would have the ices and gases associated with a comet.

Oumuamua was discovered 40 days after its closest approach to the sun, when it was already on its way out of our solar system. At this point it should have been slowing down a bit from the pull of the sun’s gravity, but instead it was speeding up slightly. This could be explained by outgassing caused by heat from the sun.

This led to a debate about whether or not Oumuamua was an asteroid with a small amount of ice, or a comet that had lost most of its ice. It seems that the object exists in the gray zone between asteroid and comet (and we run into yet another definition demarcation problem). Further, close analysis showed that Oumuamua is very elongated (often described as “cigar-shaped”) and quickly tumbling end-over-end.

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Sep 28 2018

Alien Technosignatures

I have long maintained that one of the greatest scientific questions for humanity is – are we alone in the universe? How common is life, and how common are alien technological civilizations? When we finally reach out into space, will it be empty for us to inhabit, or will we quickly encounter a galactic civilization? What will alien intelligent species be like, and what will that tell us about ourselves?

It is unfortunately likely that we will not have any real answers to any of these questions anytime soon. But that does not mean we shouldn’t look. Recently NASA held a workup to explore possible avenues of looking for alien technosignatures – signs of advanced alien civilizations that we can see from Earth. Some of the participants also held a Reddit AMA.

So – what are alien technosignatures and how can we find them?

The most basic type is radio signals. There has been an effort to listen for alien radio signals for decades, often referred to as SETI, the Search for Extraterrestrial Intelligence. The idea is that radio signals are a convenient way to communicate across lightyears, and perhaps an alien world is sending out such signals for others to find. But really, we have been looking for radio signals because we can. It’s like the person looking for a lost item under a lamp post, not because they have any reason to find it there, but because the light is good.

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Sep 11 2018

The Pluto Debate Rages On

Published by under Astronomy

If you have not watched Rick and Morty, I highly recommend it. It is an adult-themed cartoon, very entertaining, and extremely well written. On one episode Jerry, while trying to help his son Morty with a science project, mistakenly says that Pluto is a planet. When Morty corrects him, Jerry doubles-down and will not relent, going as far as to call NASA to insist that Pluto be reclassified a planet. This gets the attention of the Plutonians, who are themselves engaged in a raging controversy over whether or not Pluto is a full planet, and who enlist Jerry as an “Earth scientist” to support the planet position. This plot line is really a commentary on science denial, specifically global warming denial.

The Pluto controversy back on Earth is less intense, and the stakes are lower, but it remains and interesting debate about how to optimally categorize things in science. What categories should we have, and what criteria should we use? Should scientific utility be the only measure, or should public understanding also play a role?

Pluto was discovered in 1930 by Clyde Tombaugh and was designated as the ninth planet. Pluto has always been, for some reason, a popular favorite, maybe because of the name, maybe because it was the smallest planet. Pluto has the most eccentric orbit of any of the classic 9 planets, and it’s orbit actually crosses over the orbit of Neptune. It is also the first Kuiper belt object discovered – a region of our solar system beyond Neptune that is full of icy objects.

Problems started for our nice planetary system when other Kuiper belt objects started to get discovered. In 2005 Eris was discovered – it is slightly smaller than Pluto but is 27% more massive (because it is more dense). Eris also has a moon, Dysnomia. Two other large Kuiper belt objects have since been confirmed and named – Makemake and Haumea.

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Jul 26 2018

Water on Mars

Published by under Astronomy

It looks like Mars has become the third body in the solar system that has a body of water beneath a cover of ice. As reported by AAAS:

Between May 2012 and December 2015, the Mars Express spacecraft was used to conduct a radar survey of a region called Planum Australe, located in the southern ice cap of Mars. A tool onboard the spacecraft sends radar pulses that penetrate the surface and ice caps of the planet and reflections off subsurface features provide scientists with information about what lies below.

The scientists concluded that water was the best explanation for the radar images. This is far from confirmation, but it is a strong suggestion and certainly warrants follow up.

We have known for a long time that Mars used to be a watery planet, with flowing water on its surface. There are geological features that look like ancient river beds, for example.  In order to have surface water, however, you need an atmosphere with enough pressure and warmth, so Mars likely had a thick enough atmosphere in the past. That atmosphere was lost over time, probably due to the steady pressure of the solar winds, without any significant magnetic field to protect from it (like we have on Earth).

There is also evidence for water on Mars today – there is a tiny amount of water vapor in the thin atmosphere. There is also permanent water ice in the ice caps on Mars. There is a transient and seasonal carbon dioxide ice layer in the north and a permanent carbon dioxide layer over the southern ice cap, but both are mostly water ice. In fact, if all the ice on Mars melted, it could cover the entire surface to a depth of 35 meters. Finally there is water ice in the surface soil on Mars, which occasionally boils away at the surface.

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Jul 23 2018

Oxford Study – Reanalyzing the Drake Equation

Published by under Astronomy

Earlier this year I wrote about two ways of looking at the probability of there being advanced alien civilizations – the Drake Equation and the Fermi Paradox, and how to resolve any apparent conflict between the two. The Drake Equation is simply a series of probabilities of all the factors necessary to have technological civilizations.

The Drake Equation is:

{\displaystyle N=R_{*}\cdot f_{\mathrm {p} }\cdot n_{\mathrm {e} }\cdot f_{\mathrm {l} }\cdot f_{\mathrm {i} }\cdot f_{\mathrm {c} }\cdot L}

where:

N = the number of civilizations in our galaxy with which communication might be possible

and

R = the average rate of star formation in our galaxy
fp = the fraction of those stars that have planets
ne = the average number of planets that can potentially support life per star that has planets
fl = the fraction of planets that could support life that actually develop life at some point
fi = the fraction of planets with life that actually go on to develop intelligent life (civilizations)
fc = the fraction of civilizations that develop a technology that releases detectable signs of their existence into space
L = the length of time for which such civilizations release detectable signals into space

Of course we do not know any of the variables. All we can do is input a range of possible answers and see what range of results it spits out. That is exactly what a new study from Oxford researchers did.

This “study” does not include any new information, it is simply a new analysis of the Drake Equation, inputting what they authors think are the most reasonable figures, including the full range of our uncertainty. They argue that the uncertainty is even greater than has been previously considered the case, and when the full range of uncertainty is taken into account, the answers to how many civilizations there are out there varies by orders of magnitude.

Most importantly, the range of possible answers to the Drake Equation equals 1 – meaning that humanity is the only technological civilization in the known universe. They write:

When the model is recast to represent realistic distributions of uncertainty, we find a substantial ex ante probability of there being no other intelligent life in our observable universe, and thus that there should be little surprise when we fail to detect any signs of it.

They argue that their results resolve the Fermi Paradox, which is simply a question asked by physicist Enrico Fermi – If there are any alien civilizations out there, where are they?

Fermi was musing that, given millions of years of spacefaring technology, a civilization in our galaxy could have explored and even settled the entire galaxy. The universe is 13.7 billion years old, and our galaxy, the Milky Way, is almost as old (13.5 billion years) There are an estimated 2 trillion galaxies in the observable universe. That is a lot of time for any civilization to explore and spread out. So why aren’t we seeing them.

One might extend this argument to SETI – the search for extraterrestrial intelligence using radio astronomy. While SETI has explored only a small percentage of the sky, and in a small percentage of possible frequencies, the more we search the more we can say that the galaxy is not humming with alien signals.

The Fermi Paradox can be resolved in a number of ways. It’s possible that the resources necessary for interstellar travel are simply not worth it. It is also possible that our alien neighbors may respect our autonomy and are keeping their distance. But it may also be true that our nearest alien neighbor is a galaxy or more away, really making it not worth the resources to travel to our humble system. All this would take is for any one of the factors in the Drake Equation to be at the low end of estimates.

The one factor we are learning more about is the number of possible worlds in the galaxy that could potentially host life. The search for exoplanets, while still in its infancy, is rapidly finding thousands of worlds around other stars, and we are starting to be able to make statistical statements about typical stellar systems. The numbers are still biased by our search methods, but we are working toward a more accurate representative picture.

First, it turns out that planets are common around other stars. Further, Earth-like planets are also common. Further still, as pointed out by another recent study, this one from Australia, moons may be an even more abundant potential location for life than planets. Large moons around gas giants may have liquid water. We have two such candidates in our own system, Europa and Enceladus. But the researchers are talking more about moons in the goldilocks zone, where liquid water can exist on the surface.

So the answer to the Fermi paradox is not likely to be found in the number of potential host worlds. We can turn next to the probability of life of any kind developing, and that is where we get back to Europa and Enceladus. Even Mars may help inform this question. If we find life or the fossils of life on these other worlds in our own system, that would support the conclusion that life itself is abundant in the universe.

Until, however, we detect actual aliens or their signals, the rest of the factors in the equation are likely to remain a mystery. Put simply – we have a sample size of one. We don’t know how likely life is to develop intelligence, and intelligence technology, and how long such civilizations tend to last. We won’t know until we encounter evidence of aliens.

And, if there are few or no other aliens out there, we will never know the full answer. We would only have increasingly negative evidence and the sense that we are alone.

This does not have to be a depressing thought, however, although it would be disappointing. In response to this study, Elon Musk tweeted:

This is why we must preserve the light of consciousness by becoming a spacefaring civilization & extending life to other planets.

Sure, this is a bit self-serving as his company is trying to get to Mars and this is one of his main justifications for the effort. But it is true, none-the-less. If we are the only technological intelligent species in the galaxy or even the universe, how much the more precious are we. Carl Sagan pointed that out decades ago.

If we are the beneficiaries of a fantastically unlikely series of events, so unlikely that there is only one example in 2 trillion galaxies over billions of years, then we should take all the more care to value and preserve that civilization.

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Jun 28 2018

Complex Organic Molecules on Enceladus

Published by under Astronomy

Enceladus is one of the most interesting worlds in our solar system. It is a moon of Saturn with a surface comprised entirely of bright ice. Why is the ice so reflective? Because it is constantly replenished from a subsurface ocean of salt water, which gushes through cracks in the surface as geysers.

That is intriguing enough, but the implications are even more interesting – most significantly, there is liquid water beneath the frozen surface of Enceladus. Liquid water means a couple of things. First, it means the core of Enceladus is warm. The moon is not frozen solid through. A moon that size should have frozen solid by now, so there must be some source of energy keeping it warm.

The first thought was that tidal forces from Saturn were responsible, but scientists could not make computer models fit. However, a 2017 paper hypothesized that the core of Enceladus may be porous, and this model works. The core flexes, grinding rocks together, creating heat through friction. Further, liquid water would seep into the porous rock, heat to near boiling (90 C) and then rise to the surface and gush out through cracks. Heating would be greatest at the poles, and this is therefore also where the ice is thinnest. The model fits our observations.

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May 31 2018

Panspermia Pseudoscience

Last week I wrote about a recent article claiming evidence for panspermia (the idea that life had limited origins and then seeded itself throughout the galaxy), and the underlying idea of panspermia itself. I concluded that the new paper provided no compelling evidence, and panspermia, while not impossible, is a fringe hypothesis with no credible supporting evidence.

In response one of the co-authors of the paper (Ted Steele) wrote me an e-mail, attempting to defend the paper. I welcome the opportunity to engage in a dialogue about any topic I blog about, and so here is my response. Here is the e-mail in full:

Dear Steven:

I can see you have got quite emotional (attached) – and I am sure you are therefore not thinking straight. I tried posting this reply to your Blog comment but for technical reasons( I think ) I was excluded. So I decided to email you directly and share my response with some of your academic colleagues.

I suggest you re-read our paper carefully as you read this note. See https://doi.org/10.1016/j.pbiomolbio.2018.03.004

I am a molecular immunologist and evolutionist of 50 years standing. I am also the lead author of this paper on the “Cause of the Cambrian Explosion – Terrestrial or Cosmic? ” I do not publish scientific trivia, and apart from key books the main body of my work is published in peer reviewed journals – check me on PubMed searching “Steele EJ”. Many of my PDFs are also at my academia.edu site (below). My main field is the study of the RNA and DNA editing mechanisms in the somatic hypermutation and germline evolution of antibody variable genes – however I am very interested in pragmatically evaluating the evidence consistent with or predicted by the Hoyle-Wickramasinghe Panspermia explanatory paradigm.

I have spent 10 years or more poring over and thinking about all the multifactorial evidence and all the explanations and criticisms. I expect serious critics to do what I have done – confront all the “extraordinary ” evidence in conflict with the terrestrial paradigm. Most of my co-authors have done that. Skeptics must do this – confront and evaluate the evidence and the primary literature. Here some examples from our paper, which are paradigm shifting (that is, pure nonsense under the terrestrial neo-Darwinism paradigm).

We now have a set of extraordinary facts to explain. The usual skeptical response in these situations is that “Extraordinary Explanations require Extraordinary Evidence’. The situation now is the reverse. Extraordinary, and multifactorial evidence exists now on Earth and its immediate environs. So now we must provide an “Extraordinary” explanation that fits all these facts and makes sense of them – this has been the aim of Science since time immemorial.

Four extraordinary set of biological facts are speaking for themselves:

• Eukaryotic fossils in meteorites > 4.5 billion years old ( e.g. Murchison)

• Interstellar dust Infra red extinction spectrum = infra red extinction spectrum of freeze dried E. coli (this is the most incredible scientific result I have ever seen, see Fig 1 in our paper)

• Bacteria in the cosmic dust on the external surface of the International Space Station

• Tardigrades

I have not added a list of other data, including space hardy biological data, Mars data, nor the Octopus RNA editing data, because I do not need to – four , quite unrelated, data sets are enough for biological significance. ( Statistical significance does not enter the picture). The skeptic and traditional Astrophysicist now needs to provide a convincing explanation of these data sets that avoids Panspermia.

I am a pragmatic Popperian – I deal in hard facts that require a unifying explanation.

Yours

Ted Steele

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May 22 2018

Alien Cephalopods and Panspermia

A recent paper in Progress in Biophysics and Molecular Biology, Cause of Cambrian Explosion – Terrestrial or Cosmic?, has caused quite a stir. I think that was the intention, and the majority of journalists ate it up, either not caring if the science was good, or not able to tell.

One main point of the paper is that the Cambrian Explosion – the geologically rapid event about 550 million years ago in which multicellular life appears in the fossil record – was so rapid because it may have been the result of alien genetic information. The authors further argue cephalopods, especially the octopus, are so amazing because they either incorporated alien genes into their makeup, or they are completely alien, coming to earth as cryopreserved eggs inside comets. The third leg of their alleged evidence for panspermia is microfossils found in meteorites.

All three arguments are utter crap. The underlying claim of panspermia – that life has seeded the galaxy from one or a limited number of initial sources – is highly problematic but perhaps not 100% nonsense.

The Three Lines of Evidence

Many science bloggers have trashed this article, doing damage control for the irresponsible journalists who probably should not be covering science stories. I will only quickly summarize here.

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May 08 2018

Stephen Hawking’s Parting Shot

Published by under Astronomy

In the excellent series, Rick and Morty, the scientist Rick Sanchez invented a portal gun that allows him to jump into any of the infinite number of universes. This is a great plot device that allows for many funny and absurd scenarios. There are also parts of this idea that are not implausible, according to cosmologists.

Stephen Hawking, with coauthor Thomas Hertog, had something to say about the multi-universe theory in his final paper published 10 days prior to his death. The paper, 20 years in the making, reverses some of Hawking’s earlier positions and also, if ultimately viable, still leaves much work to be done.

This is one of those scientific arguments that is incomprehensible in its language and math outside of a small group of experts. I have no hope of reading and understanding the original paper. But I will do my best to pull together translations of the basic concepts.

In this paper Hawking and Hertog are reversing one idea introduced by Hawking many years ago, that the universe is finite but unbound in time. This is literally impossible to imagine, but his analogy is to think of how being unbound but finite in space works. Imagine the surface of a ball. You can walk around the surface and never reach an end, but that surface is finite because it is curved back in on itself. What if time worked the same way? The life of our universe is a finite time loop, with no edge.

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May 03 2018

What the Flat-Earth Movement Tells Us

Whenever I write about flat-earthers, those who, incredibly, actually believe in the 21st century that the world is flat, there are multiple comments to the effect that we are just getting punked. No one really believes the world is flat, they are just saying that to wind us up, and we are taking the bait.

But this view is demonstrably wrong. I have actually encountered flat-earthers out in the wild, so to speak – in meat space. They really do seriously entertain the theory that the earth is flat. Harry T Dyer also reports recently in Raw Story about a three day convention of flat-earthers. They weren’t tongue-in-cheek having a laugh. They were dead serious.

I think the flat-earth deniers, if you will, are missing the point. They are approaching the issue like most people do initially – looking at the claims from a scientific point of view. From that angle the claims of flat-earthers are beyond absurd. They are so extremely ignorant and illogical that it seems reasonable to consider that either there is some psychological pathology involved, or it’s just a hoax.

There is no doubt that the belief that the earth is flat is rooted in a profound scientific illiteracy. It is not only ignorant of the findings of science, but also of the history of science, and any knowledge of the institutions of science and the participation of countless students and citizen scientists. But flat-eartherism is not about scientific illiteracy – meaning it is not merely a manifestation of profound ignorance of science (which is also why it cannot be corrected with scientific information). As Dyer also points out, belief in a flat earth is ultimately about rejecting institutional knowledge itself.

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