One by one, pillars of classical logic have fallen by the wayside as science progressed in the 20th century, from Einstein’s realization that measurements of space and time were not absolute but observer-dependent, to quantum mechanics, which not only put fundamental limits on what we can empirically know but also demonstrated that elementary particles and the atoms they form are doing a million seemingly impossible things at once. (…)

Eighty-seven years ago, as far as we knew, the universe consisted of a single galaxy, our Milky Way, surrounded by an eternal, static, empty void. Now we know that there are more than 100 billion galaxies in the observable universe. (…)

Combining the ideas of general relativity and quantum mechanics, we can understand how it is possible that the entire universe, matter, radiation and even space itself could arise spontaneously out of nothing, without explicit divine intervention. (…)

Perhaps most remarkable of all, not only is it now plausible, in a scientific sense, that our universe came from nothing, if we ask what properties a universe created from nothing would have, it appears that these properties resemble precisely the universe we live in.

{ Lawrence M. Krauss/LA Times | Continue reading }

artwork { Ellsworth Kelly, White curve I (black curve I), 1973 }

The Milky Way and Andromeda are siblings, … we used to think they were near-twins. .. [But] the black hole at [Andromeda’s] heart is more than a hundred times as massive as ours. And while our galaxy is strewn with about 150 of the bright galactic baubles known as globular clusters, Andromeda boasts more than 400. … Whereas Andromeda is a pretty well-adjusted spiral, the Milky Way is an oddball – dimmer and quieter than all but a few per cent of its peers. That is probably because typical spirals such as Andromeda are transformed by collisions with other galaxies over their lifetimes. …

The Milky Way must have lived relatively undisturbed. Except for encounters with a few little galaxies such as the Sagittarius dwarf, which the Milky Way is slowly devouring, we wouldn’t have seen much action for 10 billion years. Perhaps that is why we are here to note the difference. More disturbed spirals would have suffered more supernova explosions and other upheavals, possibly making the Milky Way’s rare serenity especially hospitable for complex life.

{ NewScientist | via Overcoming Bias }

Sixty-five million years ago, a Manhattan-size meteorite traveling through space at about 11 kilometers per second punched through the sky before hitting the ground near what is now Mexico’s Yucatán Peninsula. The energy released by the impact poured into the atmosphere, heating Earth’s surface. Then the dust lofted by this impact blocked out the sun, bringing years of wintry conditions everywhere, wiping out many terrestrial species, including the nonfeathered dinosaurs. Birds and mammals thus owe their ascendancy to the intersection of two orbits: that of Earth and that of a devastating visitor from deep space. (…)

In December 2004, scientists at NASA and the Jet Propulsion Laboratory (JPL), in Pasadena, Calif., estimated there was a nearly 3 percent chance that a 30-billion-kilogram rock called 99942 Apophis would slam into Earth in 2029, releasing the energy equivalent of 500 million tons of TNT. That’s enough to level small countries or raise tsunamis that could wash away coastal cities on several continents. More recent calculations have lowered the odds of a 2029 impact to about 1 in 250 000. This time around, Apophis will probably miss us—but only by 30 000 km, less than one-tenth of the distance to the moon. (…)

We considered several strategies. The most dramatic—and the favorite of Hollywood special-effects experts—is the nuclear option. Just load up the rocket with a bunch of thermonuclear bombs, aim carefully, and light the fuse when the spacecraft approaches the target. What could be simpler? The blast would blow off enough material to alter the trajectory of the body, nudging it into an orbit that wouldn’t intersect Earth.

But what if the target is brittle? The object might then fragment, and instead of one large body targeting Earth, there could be several rocks—now highly radioactive—headed our way.

{ IEEE Spectrum | Continue reading }

painting { Nicola Verlato }

What would we do if we encountered an alien race? As it turns out, the question has garnered considerable academic thought since the first reported flying saucer sighting in 1947, not just as an inquiry in human psychology, but also as a way of contemplating what aliens might do if they ever found us. From astronomers to ufologists to anthropologists, scholars who have contemplated the various “contact scenarios” believe our course of action would strongly depend on the relative intelligence level of the newfound beings. Here, we outline what would happen if we encountered primitive, humanlike, and godlike aliens. (…)

In 1950 the U.S. military developed a procedure called “Seven Steps to Contact,” laying out the logical steps we would take upon discovering creatures with roughly human-level sentience. According to the steps, we would begin with remote surveillance and data gathering, and would eventually move on to covert visitations with the goal of gauging the performance characteristics of the aliens’ vehicles and weaponry.

{ LiveScience | Continue reading }

related { Alien Abductions May Be Vivid Dreams, Study Shows }

photo { Laerke Posselt }

The Earth has a large moon, making it unique in the inner solar system. Mercury and Venus have no moons, and Mars has only two small asteroid-sized objects orbiting it. In this essay, the father of the SMART-1 lunar mission, Bernard Foing of the European Space Agency, looks at the effect the Moon has had on the Earth, and explores how different our world would be if we had no planetary companion. Would life have evolved differently, or even appeared on Earth without the Moon?

{ Astrobio | Continue reading }

painting { Jules Joseph Lefebvre, La Vérité, 1870 }

{ 1. Wyne Veen | 2 }

unrelated { If you were thrown into the vacuum of space with no space suit, would you explode? }

The idea that our universe is embedded in a broader multidimensional space has captured the imagination of scientists and the general population alike. 

This notion is not entirely science fiction. According to some theories, our cosmos may exist in parallel with other universes in other sets of dimensions. Cosmologists call these universes braneworlds. And among that many prospects that this raises is the idea that things from our Universe might somehow end up in another.

A couple of years ago, Michael Sarrazin at the University of Namur in Belgium and a few others showed how matter might make the leap in the presence of large magnetic potentials. That provided a theoretical basis for real matter swapping. 

Today, Sarrazin and a few pals say that our galaxy might produce a magnetic potential large enough to make this happen for real. If so, we ought to be able to observe matter leaping back and forth between universes in the lab. In fact, such observations might already have been made in certain experiments.

{ The Physics arXiv Blog | Continue reading }

photo { Adam Lampton }

What occurred to Newton was that there was a force of gravity, which of course everybody knew about, it’s not like he actually discovered gravity– everybody knew there was such a thing as gravity. But if you go back into antiquity, the way that the celestial objects, the moon, the sun, and the planets, were treated by astronomy had nothing to do with the way things on earth were treated. These were entirely different realms, and what Newton realized was that there had to be a force holding the moon in orbit around the earth. This is not something that Aristotle or his predecessors thought, because they were treating the planets and the moon as though they just naturally went around in circles. Newton realized there had to be some force holding the moon in its orbit around the earth, to keep it from wandering off, and he knew also there was a force that was pulling the apple down to the earth. And so what suddenly struck him was that those could be one and the same thing, the same force.

(…)

I’m not sure it’s accurate to say that physicists want to hand time over to philosophers. Some physicists are very adamant about wanting to say things about it; Sean Carroll for example is very adamant about saying that time is real. You have others saying that time is just an illusion, that there isn’t really a direction of time, and so forth. I myself think that all of the reasons that lead people to say things like that have very little merit, and that people have just been misled, largely by mistaking the mathematics they use to describe reality for reality itself. If you think that mathematical objects are not in time, and mathematical objects don’t change — which is perfectly true — and then you’re always using mathematical objects to describe the world, you could easily fall into the idea that the world itself doesn’t change, because your representations of it don’t.

There are other, technical reasons that people have thought that you don’t need a direction of time, or that physics doesn’t postulate a direction of time. My own view is that none of those arguments are very good. To the question as to why a physicist would want to hand time over to philosophers, the answer would be that physicists for almost a hundred years have been dissuaded from trying to think about fundamental questions. I think most physicists would quite rightly say “I don’t have the tools to answer a question like ‘what is time?’ - I have the tools to solve a differential equation.” The asking of fundamental physical questions is just not part of the training of a physicist anymore.

(…)

On earth, of all the billions of species that have evolved, only one has developed intelligence to the level of producing technology. Which means that kind of intelligence is really not very useful. It’s not actually, in the general case, of much evolutionary value. We tend to think, because we love to think of ourselves, human beings, as the top of the evolutionary ladder, that the intelligence we have, that makes us human beings, is the thing that all of evolution is striving toward. But what we know is that that’s not true. Obviously it doesn’t matter that much if you’re a beetle, that you be really smart. If it were, evolution would have produced much more intelligent beetles. We have no empirical data to suggest that there’s a high probability that evolution on another planet would lead to technological intelligence. There is just too much we don’t know.

{ Tim Maudlin/The Atlantic | Continue reading }

photo { Luisa Opalesky }

Three studies released Wednesday, in the journal Nature and at the American Astronomical Society’s conference in Austin, Texas, demonstrate an extrasolar real estate boom. One study shows that in our Milky Way, most stars have planets. And since there are a lot of stars in our galaxy — about 100 billion — that means a lot of planets. (…)

Confirmed planets outside our solar system — called exoplanets — now number well over 700, still-to-be-confirmed ones are in the thousands.

{ NY Times | Continue reading }

previously { Now, just where might this Great Filter be located? }

The question confronting us today is: who owns the Geosynchronous Orbit?

In recent years, “parking spots” in the geosynchronous orbit have become an increasingly hot commodity. According to the NASA, since the launch of the first television satellite into a geosynchronous orbit in 1964, the number of objects in Earth’s orbit has steadily increased to over 200 new additions per year. This increase was initially fueled by the Cold War, during which space was a prime area of competition between the United States and the Soviet Union. Yet over two decades after the end of the US-Soviet space race, even the global financial crisis that began in 2007 does not seem to have diminished the demand for telecommunications satellites positioned in GSO. This ongoing scramble to place satellites in GSO prompted some developing equatorial countries to assert sovereignty over the outer space “above” their territorial borders, presumably with the hope of extracting rent from the developed countries that circulate their technologies overhead. So far, the international community has rejected this notion, but the legal status of the GSO remains in limbo.

{ SSRN | Continue reading }

photo { Roman Signer }

{ Distant world looks ripe for life | Distant world looks too ripe for life }

“Did you know that 95% the universe is dark matter?” (…) “What about dark energy?” (…)

It is true that most of the universe is made up of things that can’t be seen, and whose presence is inferred by its effects on the things that can be seen. But what effects do we see? And how does that translate to a percentage of the universe that remains a mystery?

Galaxies rotate, and when we use gravitational laws to predict what that rotation should look like, we find that they should behave like the solar system–the farther away something is from the central mass (in the case of the solar system, the sun, and in the case of a galaxy, the supermassive black hole at the center), the slower it should orbit; the gravitational force on Pluto, for instance, is much smaller than the gravitational force on Mercury, because it’s much farther away from the sun. A star at the fingertip of an arm of the galaxy should orbit more slowly than we do. However, that’s not really what happens: galaxies have flat rotation curves, meaning that objects farther away from the supermassive black hole don’t really orbit more slowly than things closer to it.

What this implies is that there is lots of mass spread throughout the galaxy–that most of the mass isn’t just at the center–and that the spread-out mass has a large gravitational effect on the galaxy’s rotation.

{ Smaller Questions | Continue reading }

photos { 1. Pearly | 2. Natalia Arias }

related { Computer simulations suggest that a giant planet was kicked out of our solar system billions of years ago, saving Earth in the process. But how solid are those simulations? }