Showing all posts about science
Space bubbles a Dyson sphere like solution to global warming?
15 June 2022
Dyson spheres are hypothetical mega-structures highly advanced planetary civilisations might construct around their host star to harness as much solar energy as possible to power their needs. Seen from a distance, a Dyson sphere would look like a massive shell almost completely encompassing a star.
It’d be like constructing a giant display case for the Sun. Needless to say building a Dyson sphere is no small undertaking, and would require an enormous quantity of resources, technological smarts, plus an unprecedented level of international cooperation. A single superpower could not take on an engineering feat of this scale alone, it’d be a team effort.
Dyson spheres have been in the news relatively recently. Fluctuations in the light of Tabby’s Star, located about 1,470 light-years from Earth, were puzzling astronomers, and the existence of a Dyson sphere was advanced as a possible explanation, though later ruled out.
While Dyson spheres, something late British American mathematician and physicist Freeman Dyson first wrote about in 1960, are unlikely to feature in our future anytime soon, the concept may help us combat global warming.
A team of MIT scientists have devised a solar filter of sorts, they call space bubbles. In short, a small structure made up of numerous of these space bubbles could be used to form a shield, deflecting a small, though sufficient amount of solar radiation away from the Earth.
The MIT scientists propose placing the space bubbles at the Lagrange point between the Earth and the Sun. Put simply, a Legrange point, is an area between two celestial objects, say the Earth and the Sun, where the gravity of both objects balance each other. For example if a satellite were placed at this Legrange point, it would stay put, and wouldn’t fall towards either the Earth or Sun.
Once in place, the space bubbles would act like an eclipsing body, in this case permanently blocking, or more like filtering, a small amount of the Sun’s rays reaching the Earth. While the proportion of solar radiation “blocked” would be minuscule, the MIT team say if just under two percent of “incident solar radiation” was deflected, current global warming could be fully reversed.
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astronomy, climate change, science
In ten billion years the universe will double in size
28 May 2022
The Hubble constant expresses the rate at which the universe is expanding. The problem is though, no one has been able to nail down a precise value for the constant. That is, until now.
When the Hubble Space Telescope was launched in 1990 the universe’s expansion rate was so uncertain that its age might only be 8 billion years or as great as 20 billion years. After 30 years of meticulous work using the Hubble telescope’s extraordinary observing power, numerous teams of astronomers have narrowed the expansion rate to a precision of just over 1%. This can be used to predict that the universe will double in size in 10 billion years.
That’s mind blowing. To say the least. The already enormous cosmos will one day be twice its present size. Too bad no one here today will be around to see it. But what does it matter anyway? Well, you’d be surprised. Given some two point two million new books are published every year, one can only imagine how many more publications there’ll be in ten billion years’ time.
With a much larger universe by then, it’s comforting to know there will be space to put them somewhere…
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Time’s absence may make the universe easier to understand
19 April 2022
Writer’s on a tight deadline might disagree, but some physicists are beginning to believe that time may not exist. It’s a heady concept that there’s no such thing as lunch at one o’clock, because there’s no such thing as time, but when scientists talk about time, it’s on a cosmic scale, not a human one, says Dr Sam Baron of the Australian Catholic University, writing for The Conversation.
In the 1980s and 1990s, many physicists became dissatisfied with string theory and came up with a range of new mathematical approaches to quantum gravity. One of the most prominent of these is loop quantum gravity, which proposes that the fabric of space and time is made of a network of extremely small discrete chunks, or “loops”. One of the remarkable aspects of loop quantum gravity is that it appears to eliminate time entirely. Loop quantum gravity is not alone in abolishing time: a number of other approaches also seem to remove time as a fundamental aspect of reality.
The absence of time in this context though may account for discrepancies in some of the theories that scientists use to understand the universe, such as general relativity, quantum mechanics, and string theory.
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How the rings of Saturn were formed
23 March 2022
From BBC Earth Lab. Many millions of years ago, one of Saturn’s erstwhile moons, strayed a little too close, crossed a line, the Roche Limit, and shattered into billions of pieces, having been torn apart by the immense gravity of the Solar System’s second largest planet.
Saturn’s incredible ring system was the result of this cataclysmic event, once the remnants of the moon, some seventeen trillion tons of icy material, spread out in orbit around the planet. It would have been an incredible spectacle to witness, had anyone been around to see it all happen.
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Not the centre of the Earth that Jules Verne saw
10 February 2022
The long held notion that the centre, or core, of our planet consists of solid iron, may have been up-ended by a recent study suggesting Earth’s inner core is made up of a solid iron sublattice and liquid-like light elements:
A joint research team led by Prof. HE Yu from the Institute of Geochemistry of the Chinese Academy of Sciences (IGCAS) has found that the inner core of the Earth is not a normal solid but is composed of a solid iron sublattice and liquid-like light elements, which is also known as a superionic state. The liquid-like light elements are highly diffusive in iron sublattices under inner core conditions.
Well that differs somewhat from nineteenth century French author Jules Verne’s depiction, in his 1864 novel Journey to the Center of the Earth.
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NASA finds seven earth size planets, but are they anything like Earth?
24 February 2017
After days of keeping us in suspense about a new discovery, NASA let the cat out of the bag, in the early hours of yesterday morning. The TRAPPIST optic robotic telescope, located in Chile, recently identified a dwarf star, about forty light years distant from Earth, that is host to seven planets around about the same size as Earth.
Come on now, you didn’t think NASA was going to announce that an alien civilisation had been found, did you? This is still a significant discovery though.
Particularly as three of the seven bodies orbiting TRAPPIST-1 — the star also takes its name from the Belgian operated telescope — are within its star system’s so-called Goldilocks, or habitable zone. This is an area around a star capable of supporting life, that is neither too hot, nor too cold.
It is this bit that is especially of interest, as it means these planets may harbour water in liquid form, and, as a result, potentially life of some sort. And that is obviously an exciting prospect. But talk that we may one day be able to emigrate there is well wide of the mark, to say the least.
There’s a big difference between a planet that is earth-like, and one exactly like Earth. Such bodies are called an Earth twin, or Earth analog. For example, Proxima b, an exoplanet within the habitable zone around Proxima Centauri, the nearest star to the Sun, is considered to be earth-like, as it is a rocky, or terrestrial planet.
It might have some sort of atmosphere, and possibly there could be liquid water on its surface. But Proxima b may be far from habitable, at least as far as humans are concerned. As Proxima Centauri is a red dwarf star, which are relatively cool, Proxima b would need to be quite close to the star, to be within the habitable zone.
With that sort of proximity however, Proxima b would be tidally locked, meaning the planet’s rotational period matches the time it takes to orbit the star. The result here is only one side of the planet would ever face the star.
Therefore, the day side of Proxima b would be quite warm, whereas the night side would be extremely cold. The only spots that might be conducive to life, would be near the day-night terminator. Red dwarf stars themselves pose problems for any planets they host. For instance, they are prone to emitting powerful flares, which may have the effect of sterilising nearby planets.
Not so earth-like, after all. So while some form of life may manage to eke out an existence there, the environment would hardly be suitable for human occupation. The same conditions could well apply to the planets within the Goldilocks zone of TRAPPIST-1, given it too is a relatively cool dwarf star.
I think we might be waiting a long time indeed for news that a planet as habitable as Earth is found. In the meantime we should give thought to taking greater care of our own Earth. Clearly we’re not going to be rocketing off anywhere else in any hurry.
Originally published Friday 24 February 2017, with subsequent revisions, updates to lapsed URLs, etc.
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astronomy, legacy, red dwarf, science
Life on Earth is premature: that is why we are alone in the cosmos
4 August 2016
Since the Fermi Paradox intrigues me. Life on Earth is premature. A fluke perhaps. The universe is still relatively young, that’s why we haven’t detected signs of intelligent life elsewhere.
If we compare the present age of the universe, against its projected lifespan, possibly twenty trillion years, then it has an age comparable to an eighteen day old child, who would be expected to live for seventy years. Eighteen days. That’s pretty young.
The cosmos isn’t yet mature enough to be teeming with life.
The dominant factor proved to be the lifetimes of stars. The higher a star’s mass, the shorter its lifetime. Stars larger than about three times the sun’s mass will expire before life has a chance to evolve. Conversely, the smallest stars weigh less than 10 percent as much as the Sun. They will glow for 10 trillion years, giving life ample time to emerge on any planets they host. As a result, the probability of life grows over time. In fact, chances of life are 1000 times higher in the distant future than now.
Originally published Thursday 4 August 2016, with subsequent revisions, updates to lapsed URLs, etc.
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astronomy, legacy, physics, science
Planet Nine, a captured exoplanet? How B-grade sci-fi is that idea?
6 May 2016
There has been chatter in recent months about Planet Nine, a would-be planetary body lurking on the extreme far reaches of the solar system.
The hypothetical planet is so far away, its orbital period around the Sun is estimated at ten thousand years. By comparison, Pluto, the solar system’s best known dwarf, and outermost planet, completes a lap around the Sun in about two-hundred-and-forty-eight years.
But back to Planet Nine. Before even confirming the body even exists, astronomers are trying to figure out its origins. Wouldn’t that be easier once the planet is found? Whatever, some scientists believe it formed relatively close to the Sun, before being dispatched to the solar system’s outer reaches after a run-in with Jupiter.
Others, however, think Planet Nine is an exoplanet, a once rogue exoplanet possibly, that was captured by the Sun, after straying a little too closely to our solar system.
The final scenario sounds like a plot line from a B-grade sci-fi movie, and it seems to be comparably unlikely. Planet Nine could be an extraterrestrial invader. “Planet 9 may be an exoplanet in our own solar system,” said Gongjie Li, another astronomer at Harvard’s Center for Astrophysics whose recent modelling paper explores this very possibility, among others.
I’m not sure though I like the notion of Planet Nine being described as “a plot line from a B-grade sci-fi movie”, since it’s an idea I’ve been kicking around, as if it were a cosmic soccer ball, so to speak, in one of my sci-fi writing projects.
Originally published Friday 6 May 2016. Updated Friday 24 May 2024.
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Pluto, the solar system’s other red… planet?
14 July 2015
NASA’s New Horizons space probe will probably be skimming, mere thousands of kilometres, passed Pluto around about now. That means the photos it sends in the next few days will doubtless be far sharper than the above image of Pluto and Charon, taken from a distance of approximately twenty million kilometres.
While it’s been known for sometime Pluto is reddish-brown in colour, I didn’t realise it was referred to as the solar system’s “other red planet”, with Mars being, I guess, the red planet. While both have reddish hues, their colouring comes about in quite different ways:
What color is Pluto? The answer, revealed in the first maps made from New Horizons data, turns out to be shades of reddish brown. Although this is reminiscent of Mars, the cause is almost certainly very different. On Mars the coloring agent is iron oxide, commonly known as rust. On the dwarf planet Pluto, the reddish color is likely caused by hydrocarbon molecules that are formed when cosmic rays and solar ultraviolet light interact with methane in Pluto’s atmosphere and on its surface.
Also, isn’t referring to Pluto as “other red planet”, with the operative word being planet, likely to start all sorts of arguments?
Originally published Tuesday 14 July 2015.
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astronomy, legacy, Pluto, science
Planet X? No, that idea can be crossed off the list then
18 March 2014
For a long time astronomers believed, or hoped, there was a Jupiter, or Saturn, size planet lurking out in the distant reaches of the solar system. The presence of such a body, commonly referred to as “Planet X”, they thought, might account for the odd orbital paths of some of the other outer planets, dwarf planets, and various other Trans-Neptunian Objects (TNO).
But no, a NASA backed mission, that has spent just over a year scanning the sky, did not find any evidence of a such planet:
This news comes from a paper analyzing observations by WISE, the Wide-field Infrared Survey Explorer, a scrappy little mission that spent 13 months mapping the entire sky in infrared wavelengths. This is where warm objects are bright, things like dinky stars, asteroids, galactic dust, and more. WISE was very sensitive and was able to see objects that were pretty faint. For example, it found tens of thousands of previously undiscovered asteroids, some of which get pretty near the Earth. These glow in the infrared, heated by the Sun. What it didn’t discover, though, was another giant planet in our solar system. And it’s pretty definitive: It would’ve seen a planet the size of Saturn out to a distance of 1.5 trillion kilometers, more than a tenth of a light year! A planet the size of Jupiter would’ve been seen out to twice that far.
I imagine it’s possible there are other, much smaller planets, or dwarf planets, yet to be detected, out in the solar system’s far reaches though.
Originally published Tuesday 18 March 2014, with subsequent revisions, updates to lapsed URLs, etc.
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