Posts Tagged ‘space’

Chinese scientists have teleported an object from Earth to a satellite orbiting 300 miles away in space, in a demonstration that has echoes of science fiction.

The feat sets a new record for quantum teleportation, an eerie phenomenon in which the complete properties of one particle are instantaneously transferred to another – in effect teleporting it to a distant location.

Scientists have hailed the advance as a significant step towards the goal of creating an unhackable quantum internet.

“Space-scale teleportation can be realised and is expected to play a key role in the future distributed quantum internet,” the authors, led by Professor Chao-Yang Lu from the University of Science and Technology of China, wrote in the paper.

The work may bring to mind Scotty beaming up the Enterprise crew in Star Trek, but there is no prospect of humans being able to materialise instantaneously at remote locations any time soon. The teleportation effect is limited to quantum-scale objects, such as fundamental particles.

In the experiment, photons were beamed from a ground station in Ngari in Tibet to China’s Micius satellite, which is in orbit 300 miles above Earth.

The research hinged on a bizarre effect known as quantum entanglement, in which pairs of particles are generated simultaneously meaning they inhabit a single, shared quantum state. Counter-intuitively, this twinned existence continues, even when the particles are separated by vast distances: any change in one will still affect the other.

Scientists can exploit this effect to transfer information between the two entangled particles. In quantum teleportation, a third particle is introduced and entangled with one of the original pair, in such a way that its distant partner assumes the exact state of the third particle.

For all intents and purposes, the distant particle takes on the identity of the new particle that its partner has interacted with.

Quantum teleportation could be harnessed to produce a new form of communication network, in which information would be encoded by the quantum states of entangled photons, rather than strings of 0s and 1s. The huge security advantage would be that it would be impossible for an eavesdropper to measure the photons’ states without disturbing them and revealing their presence.

Ian Walmsley, Hooke professor of experimental physics at Oxford University, said the latest work was an impressive step towards this ambition. “This palpably indicates that the field isn’t limited to scientists sitting in their labs thinking about weird things. Quantum phenomena actually have a utility and can really deliver some significant new technologies.”

Scientists have already succeeded in creating partially quantum networks in which secure messages can be sent over optical fibres. However, entanglement is fragile and is gradually lost as photons travel through optical fibres, meaning that scientists have struggled to get teleportation to work across large enough distances to make a global quantum network viable.

The advantage of using a satellite is that the particles of light travel through space for much of their journey. Last month, the Chinese team demonstrated they could send entangled photons from space to Earth. The latest work does the reverse: they sent photons from the mountaintop base to the satellite as it passed directly overhead.

Transmitting into space is more difficult as turbulence in the Earth’s atmosphere can cause the particles to deviate, and when this occurs at the start of their journey they can end up further off course.

The latest paper, published on the Arxiv website, describes how, more than 32 days, the scientists sent millions of photons to the satellite and achieved teleportation in 911 cases.

“This work establishes the first ground-to-satellite up-link for faithful and ultra-long-distance quantum teleportation, an essential step toward global-scale quantum internet,” the team write.

A number of teams, including the European Space Agency and Canadian scientists, have similar quantum-enabled satellites in development, but the latest results suggest China is leading the way in this field.


By Sarah Kaplan

Imagine you are a photon, a packet of light. You are a tiny blip of energy, hurtling through the universe on your own. But you have a twin, another photon to whom you have been intimately connected since the day you were born. No matter what distance separates you, be it the width of a lab bench or the breadth of the universe, you mirror each other. Whatever happens to your twin instantaneously affects you, and vice versa. You are like the mouse siblings in “An American Tail”, wrenched apart by fate but feeling the same feelings and singing the same song beneath the same glowing moon.

This is quantum entanglement. To non-physicists it sounds about as fantastical as singing mice, and indeed, plenty of physicists have problems with the phenomenon. Albert Einstein, whose own research helped give rise to quantum theory, derisively called the concept “spooky action at a distance.” Quantum entanglement seems to break some of the bedrock rules of standard physics: that nothing can travel faster than light, that objects are only influenced by their immediate surroundings. And scientists still can’t explain how the particles are linked. Is it wormholes? An unknown dimension? The power of love? (That last one’s a joke.)

Luckily for quantum physicists, you don’t always need to explain a phenomenon in order to use it. Ancient humans didn’t know about friction before inventing the wheel; doctors in medieval China didn’t know about antibodies when they began inoculating people against smallpox 600 years ago. Not knowing what’s behind quantum entanglement didn’t stop Jian-Wei Pan, a physicist at the University of Science and Technology of China in Shanghai, from rocketing it into space.

In a new study in the journal Science, Pan and his colleagues report that they were able to produce entangled photons on a satellite orbiting 300 miles above the planet and beam the particles to two different ground-based labs that were 750 miles apart, all without losing the particles’ strange linkage. It is the first time anyone has ever generated entangled particles in space, and represents a 10-fold increase in the distance over which entanglement has been maintained.

“It’s a really stunning achievement, and I think it’s going to be the first of possibly many such interesting and exciting studies that this particular satellite will open up,” said Shohini Ghose, a physicist at Wilfrid Laurier University in Canada. “Who knows, maybe there’ll be a space entanglement race?”

There’s good a reason world governments may soon race to test out quantum theory in orbit, and it’s not just so they can claim the title of “spookiest.” Entangled particles could one day be used for “quantum communication” — a means of sending super secure messages that doesn’t rely on cables, wireless signals, or code. Because any interference with an entangled particle, even the mere act of observing it, automatically affects its partner, these missives can’t be hacked. To hear quantum physicists tell it, entangled particles could help build a “quantum internet,” give rise to new kinds of coding, and allow for faster-than-light communication — possibilities that have powerful appeal in an era where hospitals, credit card companies, government agencies, even election systems are falling victim to cyber attacks.

But until Pan and his colleagues started their experiments in space, quantum communication faced a serious limitation. Entangled photons don’t need wires or cables to link them, but on Earth it is necessary to use a fiber optic cable to transmit one of the particles to its desired location. But fibers absorb light as the photon travels through, so the quantum connection weakens with every mile the particle is transmitted. The previous distance record for what’s known as quantum teleportation, or sending information via entangled particles, was about 140 kilometers, or 86 miles.

But no light gets absorbed in space, because there’s nothing to do the absorbing. Space is empty. This means that entangled particles can be transmitted long distances across the vacuum and not lose information. Recognizing this, Pan proposed that entangled particles sent through space could vastly extend the distance across which entangled particles communicate.

On board the Chinese satellite Micius, which launched last year, a high energy laser was fired through a special kind of crystal, generating entangled photon pairs. This in itself was a feat: the process is sensitive to turbulence, and before the experiment launched scientists weren’t completely sure it would work. These photons were transmitted to ground stations in Delingha, a city on the Tibetan Plateau, and Lijiang, in China’s far southwest. The cities are about 750 miles apart — a bit farther than New York and Chicago. For comparison, the fiber optic method for quantum teleportation couldn’t get a New York photon much farther than Trenton, N.J.

Multiple tests on the ground confirmed that the particles from the Micius satellite were indeed still entangled. Now Pan wants to try even more ambitious experiments: sending quantum particles from the ground to the satellite; setting up a distribution channel that will allow for transmission of tens of thousands of entangled pairs per second. ”

“Then the satellite can really be used for quantum communication,” he said.

The Micius satellite can also be used to probe more fundamental questions, Pan added. The behavior of entangled particles in space and across vast distances offers insight into the nature of space-time and the validity of Einstein’s theory of general relativity. Plus there’s the whole issue of what is going on with these bizarre linked photons in the first place.

“Mathematically we know exactly how to describe what happens,” Ghose said. “We know how to connect, physically, these particles in the lab, and we know what to expect when we generate and manipulate and transmit them.”

But as for how it all happens, how entangled photons know what their partner is doing, “that is not part of the equation,” she continued. “That’s what makes it so mysterious and interesting.”

By Leah Crane

HIDDEN dimensions could cause ripples through reality by modifying gravitational waves – and spotting such signatures of extra dimensions could help solve some of the biggest mysteries of the universe.

Physicists have long wondered why gravity is so weak compared with the other fundamental forces. This may be because some of it is leaking away into extra dimensions beyond the three spatial dimensions we experience.

Some theories that seek to explain how gravity and quantum effects mesh together, including string theory, require extra dimensions, often with gravity propagating through them. Finding evidence of such exotic dimensions could therefore help to characterise gravity, or find a way to unite gravity and quantum mechanics – it could also hint at an explanation for why the universe’s expansion is accelerating.

But detecting extra dimensions is a challenge. Any that exist would have to be very small in order to avoid obvious effects on our everyday lives. Hopes were high (and still are) that they would show up at the Large Hadron Collider, but it has yet to see any sign of physics beyond our four dimensions.

In the last two years, though, a new hope has emerged. Gravitational waves, ripples in space-time caused by the motion of massive objects, were detected for the first time in 2015. Since gravity is likely to occupy all the dimensions that exist, its waves are an especially promising way to detect any dimensions beyond the ones we know.

“If there are extra dimensions in the universe, then gravitational waves can walk along any dimension, even the extra dimensions,” says Gustavo Lucena Gómez at the Max Planck Institute for Gravitational Physics in Potsdam, Germany.

Lucena Gómez and his colleague David Andriot set out to calculate how potential extra dimensions would affect the gravitational waves that we are able to observe. They found two peculiar effects: extra waves at high frequencies, and a modification of how gravitational waves stretch space.

As gravitational waves propagate through a tiny extra dimension, the team found, they should generate a “tower” of extra gravitational waves with high frequencies following a regular distribution.

But current observatories cannot detect frequencies that high, and most of the planned observatories also focus on lower frequencies. So while these extra waves may be everywhere, they will be hard to spot.

The second effect of extra dimensions might be more detectable, since it modifies the “normal” gravitational waves that we observe rather than adding an extra signal.

“If extra dimensions are in our universe, this would stretch or shrink space-time in a different way that standard gravitational waves would never do,” says Lucena Gómez.

As gravitational waves ripple through the universe, they stretch and squish space in a very specific way. It’s like pulling on a rubber band: the ellipse formed by the band gets longer in one direction and shorter in the other, and then goes back to its original shape when you release it.

But extra dimensions add another way for gravitational waves to make space shape-shift, called a breathing mode. Like your lungs as you breathe, space expands and contracts as gravitational waves pass through, in addition to stretching and squishing.

“With more detectors we will be able to see whether this breathing mode is happening,” says Lucena Gómez.

“Extra dimensions have been discussed for a long time from different points of view,” says Emilian Dudas at the École Polytechnique in France. “Gravitational waves could be a new twist on looking for extra dimensions.”

But there is a trade-off: while detecting a tower of high-frequency gravitational waves would point fairly conclusively to extra dimensions, a breathing mode could be explained by a number of other non-standard theories of gravity.

“It’s probably not a unique signature,” says Dudas. “But it would be a very exciting thing.”

One of Nasa’s partners has said that he is “absolutely convinced” aliens exist – and that they are living on Earth right now.

Robert Bigelow, an entrepreneur who is working closely with Nasa on future space missions, has suggested that he knows that our planet has an alien presence that is “right under our noses”.

Mr Bigelow made the announcement during an episode of the show 60 Minutes that focused on his work with the space agency.

His company, Bigelow Aerospace, is developing an expendable craft for humans that can inflate and might provide the space habitats of the future.

They have already been tested out in journeys to the International Space Station. And the two organisations are working on further co-operation.

But during that episode Mr Bigelow began to talk about his belief in aliens – and his claim that UFOs have come to Earth and extraterrestrials have an “existing presence” here.

“I’m absolutely convinced [that aliens exist],” he told reporter Lara Logan. “That’s all there is to it.”

Asked by Ms Logan whether he also thought that UFOs had come to Earth, he said he did.

“There has been and is an existing presence, an ET presence,” Mr Bigelow said. “And I spent millions and millions and millions – I probably spent more as an individual than anybody else in the United States has ever spent on this subject.”

Ms Logan then asked if Mr Bigelow thought it was “risky” to say that he believes such things. He said that he doesn’t care what people think because it wouldn’t “change the reality of what I know”.

Mr Bigelow didn’t give any details about whether the research and private space travel that he is funding had revealed anything about aliens to him.

But he said that the hugely expensive work his company and Nasa are doing won’t be required to meet them – he said that people “don’t have to go anywhere”, because the aliens are “right under people’s noses”.

Thanks to Kebmodee for bringing this to the It’s Interesting community.

A new deep-space study by NASA shows the vast void beyond our home is dotted not only with countless galaxies and stars, but also a stunning number of supermassive black holes.

Using data collected over 80 days of observations by NASA’s Chandra X-ray Observatory spacecraft, the agency released an image that shows the largest concentration of black holes ever seen. According to scientists, the density as viewed from Earth would be equivalent to about 5,000 objects that would fit into the area of the sky covered by the full moon.

“With this one amazing picture, we can explore the earliest days of black holes in the Universe and see how they change over billions of years,” study leader Niel Brandt of Pennsylvania State University in University Park, said in a statement.

The image above shows black holes emitting x-ray energy at a variety of intensities. Red indicates low energy, medium is green, and the highest-energy x-rays observed by Chandra are blue. About 70 percent of the objects in the image are supermassive black holes, with masses estimated to range anywhere from 100,000 to 10 billion times the mass of our sun. Many date back billions of years, forming just after the Big Bang.

While invisible to the naked eye, black holes emit x-rays due to captured matter heating up as it spins faster and faster towards the object’s all-consuming center or event horizon.

By James Griffiths

Astronomers engaged in the search for extraterrestrial intelligence (SETI) are training their instruments on a star around 94 light years from Earth after a very strong signal was detected by a Russian telescope.

An international team of researchers is now examining the radio signal and its star, HD 164595 — described in a paper by Italian astronomer Claudio Maccone and others as a “strong candidate for SETI” — in the hopes of determining its origin.

“The signal from HD 164595 is intriguing, because it comes from the vicinity of a sun-like star, and if it’s artificial, its strength is great enough that it was clearly made by a civilization with capabilities beyond those of humankind,” astronomer Douglas Vakoch, president of METI International, which searches for life beyond Earth, tells CNN.

Whenever a strong signal is detected, “it’s a good possibility for some nearby civilization to be detected,” Maccone tells CNN.

Paul Gilster of the Tau Zero Foundation, which conducts interstellar research, said that if the signal was artificial, its strength suggested it would have to come from a civilization more advanced than our own.

Such a civilization would likely be Type II on the Kardashev scale, an attempt by the Soviet astronomer of the same name to categorize various technological stages of civilizations.

“The Kardashev scale is based basically on the energy that that civilization might be able to funnel for its own use,” says Maccone.

At present, our own species is somewhere near Type I on the scale, whereby a civilization is able to harness all the energy available to it on its own planet, including solar, wind, earthquakes, and other fuels.

A Type II civilization would be able to harness the entirety of the energy emitted by its star, billions of billions of watts.

Doing so would require a colossal undertaking, likely the construction of some kind of superstructure, such as a giant sphere or swarm of super-advanced solar panels popularized by astronomer Freeman Dyson that could catch and store all radiation put out by the sun.

Scientists believe superstructures are probably our best chance of detecting alien life unless they are actively trying to communicate with us.

A Dyson sphere was one of the solutions suggested to the peculiar light fluctuations detected around Tabby’s Star, which caused great excitement when they were detected last year.

Maccone is working on developing an alternative mathematical measure of how advanced civilizations are, based on the amount of knowledge and information available to them, that “might help us in the future classify alien civilizations” that we detect.

What’s happening at HD 164595?

In a statement, Seth Shostak, a senior astronomer with the SETI Institute, said that “it’s hard to understand why anyone would want to target our solar system with a strong signal.”

“This star system is so far away they won’t have yet picked up on any TV or radar that would tell them that we’re here,” he added.

METI International will be observing the star from the Boquete Optical SETI Observatory in Panama, Vakoch says, “searching for any brief laser pulses that might be sent as a beacon from advanced extraterrestrials.”

He stressed the importance of all of the SETI community following up on a signal detected by any single member.

“Without corroboration from an independent observatory, a putative signal from extraterrestrials doesn’t have a lot of credibility.”

The SETI Institute is also examining HD 164595, using the Allen Telescope Array in California.

So far, the team has not found any signals to match those originally detected by the Russian telescope, but Shostak notes that “we have not yet covered the full range of frequencies in which the signal could be located.”

“A detection, of course, would immediately spur the SETI and radio astronomy communities to do more follow-up observations.”

According to Vakoch, “if this were really a signal from extraterrestrials, we’d want to survey the target star across as much of the electromagnetic spectrum as we could.”

So is it aliens?

Probably not, says Vakoch, pointing to potential technological interference or amplification through gravitational lensing, where a signal behind a planet or other large object appears to be far stronger than it actually is, as potential causes.

Maccone says gravitational lensing is “an important possibility that should be taken into account for future SETI research.”

“We should learn how to discriminate that against real extraterrestrial signals,” he added.

Vakoch says “the greatest limitation of the May 2015 signal is that it hasn’t been replicated. Before we can give any credence to a signal as coming from extraterrestrials, we need to see it repeatedly to make sure it wasn’t just a transient phenomenon.”

“It deserves at least a few hours of observing time by SETI researchers at other locations to make sure we don’t miss an opportunity to make first contact, however remote.”

If it does prove to be transient and unexplained, HD 164595 could become another “Wow! signal,” frustratingly tantalizing and mysterious in equal measures.

Shostak writes that “of course (it’s) possible” the signal could be from an extraterrestrial civilization, but without confirmation, “we can only say that it’s ‘interesting’.”

By Aviva Rutkin

Nicknamed Earth’s evil twin, Venus seems like everything our planet is not: scorching hot, dried out and covered in toxic clouds.

But a mere one or two billion years ago, these two wayward siblings might have been more alike. New computer simulations suggest that early Venus might have looked a lot like our home planet – and it might even have been habitable.

“It’s one of the big mysteries about Venus. How did it get so different from Earth when it seems likely to have started so similarly?” says David Grinspoon at the Planetary Science Institute in Tucson, Arizona. “The question becomes richer when you consider astrobiology, the possibility that Venus and Earth were very similar during the time of the origin of life on Earth.”

Grinspoon and his colleagues aren’t the first to imagine that Venus was once hospitable. It’s similar to Earth in size and density, and the fact that the two planets formed so close together suggests that they’re made of the same bulk materials. Venus also has an unusually high ratio of deuterium to hydrogen atoms, a sign that it once housed a substantial amount of water, mysteriously lost over time.

Venus, but snowy
To simulate early Venus, the researchers turned to a model of environmental conditions often used to study climate change here on Earth. They created four versions for Venus, each varying slightly in details such as the amount of energy the planet received from the sun, or the length of a Venusian day. Where information was scant about Venus’s climate, the team filled in educated guesses. They also added a shallow ocean, 10 per cent the volume of Earth’s ocean, covering about 60 per cent of the planet’s surface.

Looking at how each version might have evolved over time, the researchers say they were encouraged to believe that the planet might have looked much like an early Earth, and remained habitable for a substantial portion of its lifetime. The most promising of the four Venuses enjoyed moderate temperatures, thick cloud cover and even the occasional light snowfall.

Could life have emerged on this early Venus? If it did, it’s certainly no more, thanks to the oceans later boiling away and volcanoes drastically reshaping the landscape around 715 million years ago. But the team is not ruling it out.

“There’s great uncertainties in understanding Earth, not only its climate history but the history of how life began,” says Michael Way at the NASA Goddard Institute for Space Studies in New York City. If it began in oceans on Earth – a theory we’ve yet to confirm – the same could be true on a waterlogged Venus. “There’s no reason that life on this world would not have existed in these oceans. But that’s about all you can say.”

Alternative histories
“Both planets probably enjoyed warm liquid water oceans in contact with rock and with organic molecules undergoing chemical evolution in those oceans,” says Grinspoon. “As far as we understand at present, those are the requirements for the origin of life.”

To bolster their findings, the team suggests a future mission to Venus should look out for signs of water-related erosion near the equator, which would provide evidence for the oceans detailed in their simulation. Such signs have already been detected by missions at Mars. NASA is currently weighing up two potential Venus projects, although neither has been confirmed. One mission would drop a probe through the clouds down to the surface, while another would orbit around the planet and image its surface.

The researchers would also like to run simulations of further alternative pasts for Venus – perhaps one where it was a desert world, or submerged in as much water as Earth, to find out which scenario is most likely to lead to the Venus we see today.

The study could also aid astronomers in their search for exoplanets, says James Kasting at Pennsylvania State University. If Venus might have once been habitable, then it suggests that other planets close to their stars might be, too. “If you make the habitable zone really wide, that raises the probability of finding an Earth.”