Category Archives: SETI

Wonder Material

Carbon is the material of the Future. Graphite, graphene, bucky-balls and nanotubes all have amazing properties. And then there’s diamond – which seems to come in several varieties, albeit rare and/or theoretical.

Making enough of any of the allotropes – different carbon forms – is rather tricky, aside from raw graphite, which can be mined. Diamonds fortunately can be made fairly easily these days – very pure diamond crystals can be (almost) made as large as one likes. Thus Jewel Diamonds, the kind De Beers sets the standard for, have to be slightly impure crystals, as they’re thus provably natural.

Carbon nanotubes are proving easier to make and to make into useful forms. One application caught my eye:

Carbon Nanotube Sheets

…which have the rather amazing property of being strong and yet massing just ~27 milligrams per square metre. If we can dope it (add a sprinkling of other elements) to make it more reflective, then it makes rather impressive solar-sail material. Sunlight’s pressure – as felt by a reflective surface facing flat to the Sun – is about 1/650 th of the sun’s gravity, so creating lift against the Sun’s gravity requires very large, light sheets. And doped CNT sheets – if 100% reflective – would experience a lift factor (ratio of light-pressure to the sail’s own weight) of 57 (!)

In theory that means a suitably steered solar-sail made of CNT sheet could send itself away from Earth’s orbit and reach a final speed of 42*sqrt(57-1) km/s ~ 315 km/s. If it swooped past Jupiter then swung in hard for the Sun, scooting past at 0.019 AU, then it would recede at ~2,200 km/s.

We’ll ponder that some more next time.

Life in the Year 100 billion trillion – Part I

If our Universe is open, either flat or hyperbolic in geometry, then it will expand forever… or at least until space-time’s warranty expires and a new vacuum is born from some quantum flip. Prior to that, most likely immensely distant, event the regular stars will go out and different sources of energy will be needed by Life in the Universe. A possible source is from the annihilation of dark matter, which might be its own anti-particle, thus self-annihilating when it collides. One possibility is that neutrinos will turn out to be dark matter and at a sufficiently low neutrino temperature, neutrinos will add energy to the electrons of atoms of iron and nickel by their annihilation. This is the energy source theorised by Robin Spivey (A Biotic Cosmos Demystified) to allow ice-covered Ocean Planets to remain hospitable for 10 billion trillion (1023) years.

Presently planets are relatively rare, just a few per star. In about 10 trillion years, or so, according to Spivey’s research, Type Ia supernova will scatter into space sufficient heavy elements to make about ~0.5 million Ocean Planets per supernova, eventually quite efficiently converting most of the baryon matter of the Galaxies into Ocean Planets. A typical Ocean Planet will mass about 5×1024 kg, be 12,200 km in diameter with 100 km deep Ocean, capped in ice, but heated by ~0.1 W/m2 of neutrino annihilation energy, for a planet total of ~50 trillion watts. Enough for an efficient ecosystem to live comfortably – our own biosphere traps a tiny 0.1% of the sunlight falling upon it, by comparison. In the Milky Way alone some 3,000 trillion (3×1015) Ocean Planets will ultimately be available for colonization. Such a cornucopia of worlds will be unavailable for trillions of years. The patience of would-be Galactic Colonists is incomprehensible to a young, barely evolved species like ours.

We’ll discuss the implications further in Part II.

Futures of the Earth

James Lovelock once estimated Earth’s biosphere would crash in about 100 million years when carbon dioxide levels dropped too low. James Kasting and Ken Caldeira updated the model to include a different photosynthetic cycle amongst land plants, pushing back Doomsday to about 900 million years in the Future. Those “900 million years” before Earth overheats is based on a certain model of Earth’s response to the Sun’s gradual rise in luminosity. That particular model assumes everything else will remain the same, but that’s unlikely. If the partial pressure of nitrogen declines, then the greenhouse effect from carbon dioxide will decline and the Earth could remain habitable to life for another 2.3 billion years. Alternatively because the greenhouse instability of the Earth is driven largely by the thermal response of the oceans, if Earth became a desert planet then it would remain habitable until the Sun reaches ~1.7 times its present output. Combined with a reduced atmospheric pressure, it means Earth might remain habitable until the end of the Sun’s Main Sequence in 5.5 billion years.

But this all assumes no technological intervention. Several scenarios are possible – a variably reflective shell engulfing the Earth is the simplest. Planet moving and Solar engineering are more dramatic possibilities. Given sufficient thrust a leisurely spiral of the Earth outwards from the Sun would compensate for the brightening, though the pace of travel would need to be rather rapid for a 6 billion trillion ton planet to escape the more dramatic stages of the Sun’s Red Giant Branch (RGB).

Once the Sun hits the Horizontal Branch/Helium Main Sequence, the habitable zone will be roughly where Jupiter will be – as the Sun’s mass loss during the RGB will cause all the orbits to expand by ~30%. The HB offers just 110 million years of stability before the Sun begins a series of dying spasms known as the Asymptotic Giant Branch. Not healthy for any of the planets. If the RGB’s mass-loss can be tweaked a bit, then the Sun won’t hit the HB at all and will slowly decline into being a helium white dwarf. Earth can remain in the white dwarf Sun’s habitable zone then for billions more years, more if it spirals inwards as it cools.

Orlando is Awesome!

Too much to tell on the very aggressive schedule here, so a detailed report will need to wait, but I met a FAN! You know who you are. Thanks for the encouragement and I promise more content – I have some actual journal paper ideas gestating and I will need input from my audience, I suspect. One is a paper on Virga-style mega-habitats and Dysonian SETI, to use a new idea from Milan Cirkovic. The other looks at exoplanets and Earth-like versus the astrobiology term of “habitable” – the two are not the same and the consequences are sobering. The recent paper by Traub (go look on the arXiv) which estimates 1/3 of FGK stars has a terrestrial planet in the habitable zone does NOT mean there’s Earths everywhere. What it does mean and how HZ can be improved as a concept is what I want to discuss.

More later. I have my talk to review and get straight in my head – no hand notes, though I have practiced it – plus I want something helpful to say to Gerald Nordley, mass-beam Guru, on the paper he graciously added me as a co-author. Also I will summarize my talk and direct interested readers to the new web-site from John Hunt, MD, on the interstellar ESCAPE plan.

Black Holes older than Time?

Two recent arXiv preprints combined make for an interesting idea. Here’s the most recent Science headline maker…

Some black holes may be older than time

…which handily has the arXiv link…

Persistence of black holes through a cosmological bounce

…Carr & Coley pose the idea that some black holes get through a cosmological Bounce (a Crunchy Big Bounce) relatively unscathed. George Zebrowski used something like that idea in his “Macrolife” novel (1979), in which Intelligent life from previous Big Crunchy Bounces survived in the Cosmic Ergosphere. Poul Anderson did it earlier in “Tau Zero” (1970), but the problem with both is that the mass of the Universe, even if it has a net spin, probably won’t form a black-hole style ergosphere when it contracts inside its own event horizon. The topology is all wrong for regular cosmology and it’s doubtful whether a white-hole style cosmos expanding in a precosmic void would ever go Big Crunch. However they might’ve been partly right, thanks to this intriguing preprint…

Is There Life Inside Black Holes?

…in which Vyacheslav I. Dokuchaev speculates that Life might orbit within supermassive black hole event horizons because it can and it might use the emissions of the Cauchy Horizon and massive time dilation for technological purposes. If Life can live inside a Black Hole, and Black Holes can survive the Crunchy Big Bounce, then might not Life survive too? Or am I speculating over a data-void on too many planks of inference? Perhaps only a dive into a Black Hole will ever tell us for sure, though whether we can ever send the news home is debatable. According to Igor Novikov we might be able to access the regions inside via a wormhole specifically dropped in…

Developments in General Relativity: Black Hole Singularity and Beyond

…which might provide a means to reach the aliens inside from past Cosmic Cycles. Perhaps that’s exactly what they want or are hoping for. Of course such vastly old entities – if they’ve survived – might be so utterly foreign to us cosmic youths that we might be unwittingly unleashing “Elder Gods” of Lovecraftian style moral indifference. Or perhaps we’d find them to be akin because of the daring that sent them across the Event Horizon in the first place? Cosmic Extreme Sports, anyone?

[found Under a Gibbous Moon]

Hydrogen Greenhouse Worlds…

The first planets to form probably attracted a primary atmosphere of H/He from the solar Nebula. In our Solar System these were driven off from the four Inner Planets and retained by the Outer Giants, but in theory smaller planets can retain such a mixture. I’ve speculated about such worlds on these blog pages before and now there’s a new arXiv piece discussing the greenhouse abilities of H/He…

Hydrogen Greenhouse Planets Beyond the Habitable Zone

…the summary conclusion being that 40 bars of H2 can keep the surface at 280 K out to 10 AU around a G type star and 1.5 AU around an M star. Thus planets with oceans of water can exist at Saturn-like orbital distances given enough primary atmosphere. Super-Earths are the most likely to retain their H/He primary atmospheres due to their higher gravity, as young stars put out a LOT of EUV light which energizes the hydrogen and strips it away in a billion years or so, if the planet is too close. Out past ~2 AU for a G-star and that effect isn’t so dramatic, thus a Super-Earth where the Asteroid Belt is today would’ve retained its primary atmosphere and probably be warm & wet.

Such a “habitable planet” is only barely defineable as habitable because it has liquid water, but is unlikely to remain warm/wet habitable if the hydrogen is exploited/depleted by methanogens making methane out of it with carbon dioxide, nor oxygenic photosynthesisers making O2, via CO2+H2O->CH2O+O2, which then reacts rapidly with hydrogen. Could another kind of photosynthesis evolve to restore the hydrogen lost? Hydrogen makers exist on Earth, so it’s not unknown in biochemical terms, but I wonder what other compound they need to release net hydrogen from methane/sugars/water?

Strange Habitats

Some recent news pieces have expanded possible locales for Life. We’ve looked at…

Supernova made Earths warmed via Dark Matter

…and we’ll look at…

White Dwarf Habitable Zones

…but a new(ish) idea is “failed stars” – brown dwarfs, but smaller than the 13 Jupiter-mass deuterium-burning limit – might be suitable for life based on other solvents like ammonia and ethane, not just water…Failed Stars for Life

Another idea, which Frederick Pohl imagined in his last Heechee novel, is Life existing inside super-massive Black Holes…

Is There Life inside Black Holes?

…a Kerr-Newmann Black Hole (i.e. A spinning one) has a region between its inner and outer event horizons which permits stable orbits, thus providing a locale for adventurous Lifeforms to exist. Just how they would get power for living and avoid in-falling matter from beyond the outer horizon is speculative, at best, but truly advanced entities might want direct access to the singularity that might exist within.

But does General Relativity give us a sure guide to the interior of Black Holes? Theo M. Nieuwenhuizen has applied some alternative gravity theories to black holes, with the interesting result that instead of infinite blue-shift at the event horizon, and even more bizarre phantasmagoric phenomena within, instead the mass of the collapsed star might form a giant Bose-Einstein Condensate, without any of the singularities and weird horizons of regular GR. Of course whether the particular gravity theory is correct requires experimental confirmation, but it does suggest that plain-old GR, as Einstein gave it to us, might be incomplete.

Fermions & the Fermi Paradox II

Since my first brief note on R.J.Spivey’s essay two newer versions have appeared…

Version 1: From fermions to the Fermi paradox: a fertile cosmos fit for life?

Version 2: Fermi’s pardox and the interpretation of the stelliferous era

Version 3: A biotic cosmos demystified?

…while other researchers have asked whether Dark Matter has a role in making habitable planets in the present day…

Dark Matter and the Habitability of Planets

…the latter arguing that self-annihilating Dark Matter (whatever it might be) may be a significant energy source for starless planets near the Galactic Core. If Spivey’s thesis is correct, then such planets are prime targets for would-be Galactic Colonists to begin their multi-gigayear “conquest”.

White Dwarfs and the Long Dark

White Dwarfs are already relatively common in the Galaxy, but as the Universe ages they will proliferate. About 200 billion will form before the gas runs out for star formation in the Milky Way. But by then the Milky Way and Andromeda’s M31 will merge as ‘Milkomeda’ – a largish Elliptical Galaxy – roughly doubling the numbers. Stars will age and brighten as Milkomeda ages at ever smaller stellar masses, until all the fusible gases are depleted and stars are too small to fuse.

In the Long Dark that follows, every 100 billion years, star corpses and wannabe stars, the brown dwarfs, will collide with sometimes spectacular results. A brown dwarf and white dwarf collision will probably result in either a renewal of fusion burning for the white dwarf or a nova explosion. Two brown dwarfs colliding could produce an low mass star or a renewed hot brown dwarf glowing from the collision’s kinetic energy. Two white dwarfs colliding could have a number of outcomes – with enough energy the helium or carbon fusion Main sequences can be triggered. Alternatively a mass above the Chandrasekhar Limit, or close to it, can produce a thermonuclear detonation, with the stars totally disrupted in a Type Ia Supernova.

According to the Fertile Cosmos proposal of R.J.Spivey each Type Ia conflagration produces sufficient heavy elements to make roughly 450 thousand Earth mass ocean planets. These, in turn, are warmed via neutrino pair-annihilation in their iron cores, sufficient to keep their sub-glacial oceans warm for a 100 billion trillion years.