Detecting and analyzing the information carried by gravitational waves is now allowing us to observe the Universe in a way never before possible. It has opened up a new window of study and has already given us a deeper understanding of cataclysmic events and ushered in exciting new research in physics, astronomy, and astrophysics. Historically, scientists have relied almost exclusively on electromagnetic EM radiation visible light, X-rays, radio waves, microwaves, etc.
Each of these sources of information provides scientists with a different but complementary view of the Universe. Gravitational waves, however, are completely unrelated to EM radiation. They are as distinct from EM radiation as hearing is to vision. Thus, they are unique messengers of information about cosmic events. Having this new 'sense' with which to observe the Universe is important because things like colliding black holes are utterly invisible to EM astronomers. To LIGO, however, such events are beacons in the vast cosmic sea. But that number will grow as. Ground telescopes like the Subaru are much more powerful light-gatherers than space telescopes like the Hubble , chiefly because nobody has yet figured out how to squeeze a foot mirror into a rocket and blast it into space.
But ground telescopes have a serious drawback: They sit under miles of our atmosphere. This is accomplished by directing the light from a star onto a shape-shifting mirror, smaller than a quarter, activated by 2, tiny motors.
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Next comes the squinting part. But the eventual result, once the next-gen telescopes are built, will be a visible dot of light that is actually a rocky planet. Shunt this image to a spectrometer, a device that can parse light into its wavelengths, and you can start dusting it for those fingerprints of life, called biosignatures.
We already have a planet to prove it. On Earth, plants and certain bacteria produce oxygen as a by-product of photosynthesis. So if we can find evidence of it accumulating in an atmosphere, it will raise some eyebrows. Even more telling would be a biosignature composed of oxygen and other compounds related to life on Earth. Most convincing of all would be to find oxygen along with methane, because those two gases from living organisms destroy each other.
Finding them both would mean there must be constant replenishment. It would be grossly geocentric, however, to limit the search for extraterrestrial life to oxygen and methane. Life could take forms other than photosynthesizing plants, and indeed even here on Earth, anaerobic life existed for billions of years before oxygen began to accumulate in the atmosphere.
Mysterious objects at the edge of the electromagnetic spectrum
As long as some basic requirements are met—energy, nutrients, and a liquid medium—life could evolve in ways that would produce any number of different gases. The key is finding gases in excess of what should be there. There are other sorts of biosignatures we can look for too. The chlorophyll in vegetation reflects near-infrared light—the so-called red edge, invisible to human eyes but easily observable with infrared telescopes.
But the vegetation on other planets might absorb different wavelengths of light—there could be planets with Black Forests that are truly black, or planets where roses are red, and so is everything else. And why stick to plants? Lisa Kaltenegger, who directs the Carl Sagan Institute at Cornell University , and her colleagues have published the spectral characteristics of microorganisms, including ones in extreme Earth environments that, on another planet, might be the norm. The light-gathering capacity of its meter feet mirror will exceed all existing Subaru-size telescopes combined.
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They are smaller and dimmer than our sun, a yellow dwarf, so their habitable zones are closer to the star. The nearer a planet is to its star, the more light it reflects. Alas, the habitable zone of a red dwarf star is not the coziest place in the galaxy. This would render half the planet too hot for life, the other half too cold. The midline, though, might be temperate enough for life.
But he agrees with Seager that the best chance of finding life will be on an Earth-like planet orbiting a sunlike star.
Breakthrough Starshot is an ambitious plan in development to send tiny probes on a year journey to the exoplanet Proxima Centauri b. But even a featherweight spacecraft needs fuel. The farther it goes, the more it needs. The proposed solution? Forget fuel: Launch it from an orbiting satellite and propel it with Earth-based lasers.
Each probe has a quarter-inch chip weighing five grams or less that performs the roles of a camera, computers, and. Breakthrough Starshot is an ambitious plan in development to send tiny probes on a year. Forget fuel: Launch it from an.
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Situated in low Earth orbit, a satellite houses thousands of probes. When the individual probes are released, their sails automatically unfurl. On Earth, nearly a billion laser beams are directed at a probe to create a pulse with the power of gigawatts, lasting several minutes.
Proxima b after a voyage of more than 20 years. During its high-speed flyby, it takes images and records a range of data. The probe beams the information back using a laser embedded in its chip. Each transmission takes about four years to reach the Earth. Its design consists of 28 panels arranged around a center hub like a giant sunflower, more than feet across. The petals are precisely shaped and rippled to deflect the light from a star, leaving a super-dark shadow trailing behind. The two spacecraft will work together in a sort of celestial pas de deux: Starshade will amble into position to block the light from a star so WFIRST can detect any planets around it and potentially sample their spectra for signs of life.
Then, while WFIRST busies itself with other tasks, Starshade will fly off into position to block the light of the next star on its list of targets. Though the dancers will be tens of thousands of miles apart, they must be aligned to within a single meter for the choreography to work.go
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Seager, who hopes to lead the project, is confident. One can only hope. The ATA is the only facility on the planet built expressly for detecting signals from alien civilizations. Funded largely by the late Microsoft co-founder Paul Allen, it was envisioned as an assembly of radio telescopes, with dishes six meters 20 feet in diameter. But owing to funding difficulties—a regrettable leitmotif in SETI history—only 42 have been built. Smoke veils the view of the surrounding mountains, and in the haze the dishes seem primordially still, like Easter Island statues, each one staring implacably at the same spot in a featureless sky.
Richards takes me to one of the dishes, opening the bay doors beneath it to reveal its newly installed antenna feed: a crenellated taper of shiny copper housed in a thick glass cone. SETI scientists have focused in particular on a quiet zone in the radio spectrum, free of background noise from the galaxy.
It made sense to search in this relatively undisturbed range of frequencies, since that would be where sensible aliens would be most likely to transmit. Richards tells me that the ATA is working through a target list of 20, red dwarfs. In the evening, he makes sure everything is working properly, and while he sleeps, the dishes point, the antennas rouse, photons scuttle through fiber optic cables, and the radio music of the cosmos streams to enormous processors.
So far, however, all the signals of interest have been false alarms. Unfortunately, Congress long ago lost interest in dipping the cup, abruptly terminating support in The good news is that SETI the research endeavor, if not SETI the institute, has recently received a remarkable boost in funding, sending ripples of excitement through the field. Before that, he founded a highly successful internet company in Russia.
He tells me about his background—a degree in physics, a lifelong passion for astronomy, and parents who named him after the cosmonaut Yuri Gagarin, who became the first human in outer space seven months before Milner was born. That was in , which he points out is the same year SETI began. Appreciating the magnitude of this challenge requires some perspective. The first Voyager spacecraft, launched in , took 35 years to enter interstellar space.