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Sweater Weather Streaming: 20 Classic Cozy Movies

As temperatures drop, curling up with a great movie is becoming more tempting. While a spooky movie or an action-packed thriller might add some excitement to your evening, a heartfelt movie is perfect for a cozy night. Sweater weather calls for classic tales of romance and poignant family dramas. Here are twenty that are perfect for chilly evenings at home.

The Holiday

Amanda Woods, a movie producer from Los Angeles, and Iris Simpkins, a columnist from London decide to trade homes for a short vacation. Once they switch places they develop unexpected relationships that just may change the course of their lives. Both women have been unlucky in love. But when Amanda meets a charming neighbor and Iris makes a new friend in LA, will their luck change?  The Holiday  is a delightfully sweet movie with a fantastic cast that’s a perfect option for dinner and a movie in the comfort of your home. 

Practical Magic 

Sally has vowed to never love again but when rushes to rescue her sister Gillian from a dark romance that’s turning deadly, a new person enters her life and makes her question everything. The Owens sisters have endured bullying for generations and have learned to stick together. As the pair finds themselves in over their heads, they struggle to find a way out of their mess and reimagine a future for their magical lineage. Sisterly love and second chances propel  Practical Magic , a 90s classic with an ethereal aesthetic and a compelling plot. 

Brown Sugar

Dre and Sidney fell in love with hip-hop together as children. But could they have a deeper connection? In  Brown Sugar,  we follow Dre and Sidney as they follow their love of hip-hop. Life takes them in different directions but their hearts keep pulling them together. Can they find a way to honor their passions and find a way forward together or do they need to go their separate ways?  Brown Sugar  showcases Black love against a backdrop of a rich musical landscape. It’s a must-see movie. 

The Photograph 

The Photograph  tells the story of a young woman, Mae who learns about her late mother, Christina’s, life by inheriting a box shortly after Christina’s passing. Through reading a letter left in the box for her, Mae uncovers her mother’s inner world and begins to establish a bond with her.  As Mae discovers more about her mother, who was once an iconic photographer, she is approached by Michael, a journalist who is writing about Mae’s mother. Micheal and Christina grow closer and come up against their histories and hang-ups to figure out how to move forward in love. 

B.A.P.S  starring Halle Berry and the late Natalie Ann Desselle-Reid is an outrageously adorable movie about two friends who fly to California to pursue their dreams. They are deflated quickly after an audition goes south, but their luck changes when they are approached by someone offering to pay them handsomely to pose as the distant family members of a wealthy man. This classic comedy is available on Hulu with the Showtime add-on. It’s an unforgettably funny journey with an ending as sweet as the relationships that develop along the way. 

Reign Over Me

After losing his wife and children in a tragic terrorist attack, Charlie Fineman is drifting through life as a shadow of himself until he reconnects with his old friend in  Reign Over Me,   streaming now with Hulu’s Showtime add-on. Charlie’s old friend, Alan Johnson, is a dentist who’s struggling to meet the challenges of maintaining a family and a business. Alan tries to support his friend while respecting his boundaries and what follows is a heart-wrenching and deeply bittersweet story about friendship and grief that will blow you away. 

The Lake House 

Sandra Bullock and Keanu Reeves play people who fall for each other while living two years apart in  The Lake House , a sleepy little classic based on a South Korean film called Il Mare. When Dr. Kate Forster sells her lakehouse in 2006 and writes a letter to the new owner, she wasn’t expecting that her letter would somehow travel back in time to 2004 and that an amazing new friend, Alex Wyler, would come across it. As they start sending letters back and forth and discover that they are in two different years they begin to explore how they can connect and defy their realities. Will they find a way to maintain their relationship across space and time? 

Stepmom 

Transitions in families can bring all sorts of issues to the surface and that is illuminated in the blended family at the center of this family drama.  Stepmom , available on Hulu, tells the story of a family transitioning after a divorce and the challenges around the children accepting their new stepmom Isabel, played by Julia Roberts. The kids, Anna and Ben, have a hard time adjusting and things become even more challenging when their assertive no-nonsense mother Jackie, played by Susan Sarandon, shares a devasting secret. What springs forth from these challenging circumstances is a story about love and forgiveness that will warm your heart. 

Notting Hill 

Notting Hill  is a sweet and odd classic romantic comedy. Although it’s over 20 years old the love story at the center of the movie is timeless. Julia Roberts is a charming movie star that has a chance encounter with Hugh Grant at his travel bookstore. From there they have a romance that endures the slings of the paparazzi, a series of unfortunate events, and eventually, they have to decide whether to let go of their pride and let love reign. 

Boomerang 

Infamous playboy Marcus Graham, played by Eddie Murphy, meets his match in  Boomerang , a hilarious and fast-paced classic romantic comedy. After a romantic encounter with his new boss, Jacqueline Boyer, his world turns upside down and he is forced to reconsider his entire way of life. What results is a delicious moment where the tables have turned and he learns that there may be a bit more to love and relationships than he originally thought. 

You’ve Got Mail 

Before smartphones and streaming services, Kathleen Kelly and Joe Fox connect over email in  You’ve Got Mail . Kathleen is a small bookstore owner and Joe is posed to take over her block and her business as the owner of a large corporate chain.  When they meet in real life, unaware of their virtual connection, they are at odds, until Joe uncovers the truth. When Joe gets closer to Kathleen he is faced with a choice, reveal his identity and profess his love or play it safe and maintain his friendship with a lie? You’ve Got Mail is a feel-good film, available on Hulu, starring Tom Hanks and Meg Ryan that may make you roll your eyes but will also warm your heart. 

The Proposal 

When austere businesswoman, Margaret Tate, enlists her employee Andrew Paxton, to pretend to be her fiancé to avoid deportation, she is forced to meet his family in Alaska. Their fake engagement sets off a wild ride chock full of hilarious moments. From midnight sing-alongs to gut-busting moments with the grandmother, and so much more this film will have you in stitches.  The Proposal  is a light-hearted romantic comedy that you should definitely add to your Hulu favorites. 

Sleepless in Seattle

A young boy calls into a radio show and attempts to find love for his grieving father, Sam Baldwin, a year after his mother’s death. Women nationwide are enamored by the father and looking to connect with him but he is not ready to move on. One of these women is Annie Reed, a reporter from Baltimore played by Meg Ryan, who just might be the one if they can ever meet long enough to have a conversation.  Sleepless in Seattle  is a slow burn with a satisfying ending and a story that will make you believe in love available on Paramount Plus. 

What if you were in an accident that wiped your memory and you forgot everything about your life? How would you deal with a loved one longing to be remembered? In  The Vow , Paige Collins, played by Rachel McAdams, is dealing with that exact situation. When Paige is injured in a terrible car crash, she forgets everything, including her loving husband Leo, played by Channing Tatum. Can she fall in love with him all over again?  The Vow  is based on a true story and explores how the relationship develops after the accident. It’s a heartwarming tale about the power of love. 

Maid in Manhattan

Maid in Manhattan , available on Hulu, follows Marisa Ventura, a level-headed working-class mother, hoping to move up the ranks at the prestigious Beresford Hotel in New York. When one spontaneous choice leads to Marisa crossing paths with handsome politician Christopher “Chris” Marshall, she poses as a wealthy guest. Will he lose interest when he finds out what she does for a living or will they ride off into the sunset together?  Maid in Manhattan  is a lovely light movie that is a great addition to a cozy season movie list. 

Last Holiday 

Georgia Byrd, played by Queen Latifah,  is a cautious sales associate at a struggling department store. When she learns that she only has a few weeks to live, she decides to go on a lavish vacation. While on vacation in Europe she makes a group of well-to-do friends, including the owner of the department store. As her vacation comes to an end and her new friends learn more about her,  Last Holiday , streaming now on Paramount Plus, tells a beautiful story about living life fully and cherishing each moment.

The Fundamentals of Caring 

Trevor is a young man in need of a caretaker, Ben is a writer in need of a job. What could go wrong? Trevor is a wisecracking yet sheltered kid looking for an adventure so when his new caretaker Ben, suggests a road trip he’s eager to go. The trip sets in motion a series of bizarre events that build their friendship, help Trevor to come into his own, and teach them both about vulnerability and courage.  The Fundamentals of Caring  is an endearing movie that will make you laugh as much as it makes you cry. 

Saving Face 

A pregnant widow is forced to move in with her lesbian daughter and their relationship is put to the test in this romantic comedy steeped in Chinese American culture.  Saving Face  is a witty and entertaining story that touches on the trials and tribulations of mother-daughter relationships and breaking with convention. 

The Water Man 

Eleven-year-old, Gunner Boone and his mother Mary, played by Rosario Dawson are trying to fit in after moving to a small Oregon town in  The Water Man.  Gunner’s father, Amos, struggles to connect with his son but can’t seem to bridge the gap between them. Between dealing with his mother’s leukemia diagnosis and feeling isolated from his father, Gunner is seeking out friendship and adventure when he comes across a town legend and a fast-talking friend, Jo. A mythical creature that threatens to destroy a small town leads a young man with a big imagination and his streetwise friend on an unforgettable adventure. The pair face challenges large and small as they gear up to go head to head with a dark force as they forge a powerful friendship. 

Where’d You Go, Bernadette? 

When Bernadette is confronted with an impossible choice she makes a decision that upends her family and sends her husband and daughter on a mad dash to find her.  Where’d You Go, Bernadette? , streaming now on Hulu, is a beautiful film that explores themes of loss, familial relationships, and the pursuit of seemingly impossible dreams. It’s a hopeful yet emotional story that is perfect for a night in. 

Have you seen any of these cozy classic movies? They are all available on streaming services and will take you on an emotional journey from laughter to tears and back again from the comfort of your carefully crafted blanket fort. Treat yourself to a bowl of something comforting and a movie marathon. You won’t regret it. 

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This is the story of all mothers

Published by jthreeNMe on April 25, 2021

This is the story of a woman who lives with doubt.

Who constantly questions her decisions, actions, and feelings.

This is the story of a woman who undervalues herself and the role she plays in her family's life.

Clinging to the falsehood that an unpaid job, like raising kids, ain't deserving of too many accolades or complacent contentment.

This is the story of a woman who complains.

Probably too much, but because doing so and being honest with herself and the world about her struggles enables her to get through them.

This is the story of a woman on her knees asking to be reminded of her inherent worth.

Knowing that His reminders of such are what give her the strength to relentlessly strive to raise children who don't doubt theirs.

This is the story of a woman who is sure she's not getting it 'right' all the time.

The story of a human struggling to navigate the ever-changing course that is motherhood, marriage, and being an overall good person.

The story of a woman who seeks balance, solace, joy, grace, and damn, what she wouldn't give if she could find them all and they could eternally live in harmony.

The story of a woman who prays because her faith in herself often needs a boost from the One in whom she puts hers.

The story of a woman who is blind to her beauty.

The kind of beauty you don't squeeze into a tight dress or put lipstick on.

The kind of pretty that radiates from the heart, allowing others to see the genuine nature of hers.

The story of a woman whose smile might deceive you. Not because she's not happy -- she is, incredibly -- but because she wears the weight of ensuring everyone around her is too, and that ish can get heavy.

This is the story of a woman who is undoubtedly capable of moving mountains and in a million small ways every day, that's exactly what she does, often without recognizing it. This is the story of a mother.

This is the story of all mothers.

And like the ones the before her, just as the ones that'll come after her, she will prevail. Because that's what mothers do.

This post comes from the TODAY Parenting Team community, where all members are welcome to post and discuss parenting solutions. Learn more and join us ! Because we're all in this together.

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Saturday, May 08, 2021

What did einstein mean by “spooky action at a distance”.

“I cannot seriously believe [in quantum mechanics] because the theory is incompatible with the requirement that physics should represent reality in space and time without spooky action at a distance...”

“For this reason I tend to believe that quantum mechanics is an incomplete and indirect description of reality which will later be replaced by a complete and direct one.”

Sorry, Einstein. Quantum Study Suggests ‘Spooky Action’ Is Real.

By John Markoff

• Oct. 21, 2015

In a landmark study, scientists at Delft University of Technology in the Netherlands reported that they had conducted an experiment that they say proved one of the most fundamental claims of quantum theory — that objects separated by great distance can instantaneously affect each other’s behavior.

The finding is another blow to one of the bedrock principles of standard physics known as “locality,” which states that an object is directly influenced only by its immediate surroundings. The Delft study , published Wednesday in the journal Nature, lends further credence to an idea that Einstein famously rejected. He said quantum theory necessitated “spooky action at a distance,” and he refused to accept the notion that the universe could behave in such a strange and apparently random fashion.

In particular, Einstein derided the idea that separate particles could be “entangled” so completely that measuring one particle would instantaneously influence the other, regardless of the distance separating them.

Einstein was deeply unhappy with the uncertainty introduced by quantum theory and described its implications as akin to God’s playing dice.

But since the 1970s, a series of precise experiments by physicists are increasingly erasing doubt — alternative explanations that are referred to as loopholes — that two previously entangled particles, even if separated by the width of the universe, could instantly interact.

The new experiment, conducted by a group led by Ronald Hanson, a physicist at the Dutch university’s Kavli Institute of Nanoscience , and joined by scientists from Spain and England, is the strongest evidence yet to support the most fundamental claims of the theory of quantum mechanics about the existence of an odd world formed by a fabric of subatomic particles, where matter does not take form until it is observed and time runs backward as well as forward.

The researchers describe their experiment as a “loophole-free Bell test” in a reference to an experiment proposed in 1964 by the physicist John Stewart Bell as a way of proving that “spooky action at a distance” is real.

“These tests have been done since the late ’70s but always in the way that additional assumptions were needed,” Dr. Hanson said. “Now we have confirmed that there is spooky action at distance.”

According to the scientists, they have now ruled out all possible so-called hidden variables that would offer explanations of long-distance entanglement based on the laws of classical physics.

The Delft researchers were able to entangle two electrons separated by a distance of 1.3 kilometers, slightly less than a mile, and then share information between them. Physicists use the term “entanglement” to refer to pairs of particles that are generated in such a way that they cannot be described independently. The scientists placed two diamonds on opposite sides of the Delft University campus, 1.3 kilometers apart.

Each diamond contained a tiny trap for single electrons, which have a magnetic property called a “spin.” Pulses of microwave and laser energy are then used to entangle and measure the “spin” of the electrons.

The distance — with detectors set on opposite sides of the campus — ensured that information could not be exchanged by conventional means within the time it takes to do the measurement.

“I think this is a beautiful and ingenious experiment and it will help to push the entire field forward,” said David Kaiser, a physicist at M.I.T., who was not involved in the study. However, Dr. Kaiser, who is with another group of physicists who are preparing to perform an even more ambitious experiment next year that will soon measure light captured at the far edges of the universe, also said he did not think every scintilla of doubt had been erased by the Dutch experiment.

The tests take place in a mind-bending and peculiar world. According to quantum mechanics, particles do not take on formal properties until they are measured or observed in some way. Until then, they can exist simultaneously in two or more places. Once measured, however, they snap into a more classical reality, existing in only one place.

Beyond the immediate result, physicists noted that the experiment represented an advance in the understanding of a Lilliputian world that was once largely the province of theory. Quantum mechanics has already had a huge impact on modern technology and industry. For example, it is the foundation for modern computers and lasers.

“What I do find interesting is that the experimenters are learning how to manipulate quantum systems, and do experiments that are far beyond what was possible when I was starting in physics,” said Leonard Susskind, a theoretical physicist at Stanford. “Things which were at best ‘thought experiments’ become possible, then routine. That is incredibly impressive.”

Indeed, the experiment is not merely a vindication for the exotic theory of quantum mechanics, it is a step toward a practical application known as a “quantum Internet.” Currently, the security of the Internet and the electronic commerce infrastructure is fraying in the face of powerful computers that pose a challenge to encryption technologies based on the ability to factor large numbers and other related strategies.

Researchers like Dr. Hanson envision a quantum communications network formed from a chain of entangled particles girdling the entire globe. Such a network would make it possible to securely share encryption keys, and know of eavesdropping attempts with absolute certainty.

For some physicists, even though the new experiment claims to be “loophole free,” the matter is not completely closed.

“The experiment has closed two of the three major loopholes beautifully, but two out of three isn’t three,” Dr. Kaiser said. “I believe in my bones that quantum mechanics is the correct description of nature. But to make the strongest statement, frankly we’re not there.”

A potential weakness of the experiment, he suggested, is that an electronic system the researchers used to add randomness to their measurement may in fact be predetermined in some subtle way that is not easily detectable, meaning that the outcome might still be predetermined as Einstein believed.

To attempt to overcome this weakness and close what they believe is a final loophole, the National Science Foundation has financed a group of physicists led by Dr. Kaiser and Alan H. Guth, also at M.I.T., to attempt an experiment that will have a better chance of ensuring the complete independence of the measurement detectors by gathering light from distant objects on different sides of the galaxy next year, and then going a step further by capturing the light from objects known as quasars near the edge of the universe in 2017 and 2018.

Because of an editing error, an earlier version of a picture caption with this article misstated the given name of a scientist involved in the experiment. As the article correctly noted, he is Ronald Hanson, not Robert.

How we handle corrections

600-Year-Old Starlight Bolsters Einstein's 'Spooky Action at a Distance'

A group of scientists has used starlight to test a feature of quantum mechanics that gave Albert Einstein the creeps.

Entanglement is what Einstein referred to as "spooky action at a distance." It's a phenomenon by which one particle can effectively "know" something about another particle instantaneously, even if those two particles are separated by a great distance. It appears to go against the idea that nothing, not even information, can travel faster than the speed of light.

Scientists who study this phenomenon want to be sure that nothing in their experimental setup is somehow creating the illusion of entanglement, perhaps via some physical mechanism or phenomenon that scientists don't yet know about. In an effort to close a possible loophole in entanglement experiments, a group of researchers used starlight as part of their experiment.  The researchers say the results of their work provide further support for this "spooky" phenomenon. [ Quantum Entanglement: Love on a Subatomic Scale ]

Universal speed limit

If humans were to discover an intelligent species living on a planet 10 light-years away, it would take 10 years to send them a message that said "hello," and 10 more years for their reply to come back to Earth. If we discovered a civilization on an even more distant planet, it could take many human lifetimes just to start a conversation.

That's the law, according to Einstein: nothing can travel faster than the speed of light, so communications conducted over vast cosmic distances come with an inherent delay.

And yet, there is a feature of quantum mechanics that seems to violate that principle. Quantum mechanics is an area of physics that deals with subatomic particles. In this seriously small realm, things behave in a way that can seem totally contradictory to what we experience in the macroscopic world. One quantum phenomenon called entanglement postulates that pairs of entangled particles can effectively exchange information instantaneously. In theory, these particles could communicate instantly over vast cosmic distances.

This idea rattled Einstein; he never fully accepted it . And even today, scientists are working to make sure this strange phenomenon is real.

Entanglement

One of the more famous fables in quantum mechanics is about poor Schrödinger's cat , who got stuck in an uncertain state: the feline was neither alive nor dead until someone opened the box to find out. Uncertainty is another one of the truly freaky features of quantum mechanics. In the real world, something can either be alive or dead; in the quantum world, there's a third option in which the object's state hasn't yet been determined. To break the uncertainty, someone has to measure it (open the box) and force the object (cat) into one state (alive/dead).

Entangled particles also exist, initially, in an uncertain state. Particles can't be alive or dead, so instead think heads and tails. If you flip a coin 100 times, odds are it will come up heads close to 50 times and tails close to 50 times. If I then flip my own coin 100 times, there's a high probability the split will also be close to 50/50. But if our coins are entangled, then the outcome of your flip determines the outcome of my flip — perhaps our entanglement is such that every time you flip heads I flip tails. If we flip our coins enough times, our entanglement will begin to become obvious, because my outcome of my flip is no longer random, but determined by your flip, and the odds of my flipping tails every time you flip heads get lower and lower the more we flip.

That's sort of how scientists can measure entanglement. Instead of flipping a pair of coins over and over again, researchers measure the properties in many, many of pairs of entangled particles (entanglement can only be measured in a pair of particles once). But the scientists have to be sure that what they're seeing isn't just random chance.

A statement from the Massachusetts Institute of Technology (MIT) poses the question, "What if there were some other factors or hidden variables correlated with the experimental setup, making the results appear to be quantumly entangled, when in fact they were the result of some nonquantum mechanism?"

In other words, how can scientists be sure there's not some unseen factor affecting their experiments, and making it seem as though the examined particles are entangled, when in fact they are not?

A physicist named John Bell showed that if entanglement exists, then there must be a minimum degree of correlation between entangled particles when scientists measure them; this is known as Bell's inequality or Bell's theorem.

In some entanglement experiments , the detector measures a property of light particles called polarity; the detector must be oriented in one of two directions, and only photons polarized in the same direction (one of two possibilities) can pass through. In order to make sure that the detector is not somehow influenced by one of those mysterious forces that could corrupt the experiment, researchers will use random-number generators to determine the direction of the detector.

That random choice is made "in the split second between when the photon leaves the source and arrives at the detector," according to the MIT statement. "But there is a chance, however slight, that hidden variables, or nonquantum influences, may affect a random number generator before it relays its split-second decision to the photon detector,” the statement said.

This particular "loophole" in an experiment testing Bell's inequality is known as the "freedom-of-choice loophole." In 2014, a couple of scientists got together and came up with a new idea for how to avoid those possible influences, using starlight as the thing that randomly determines the direction of the detector. Now, those researchers have put their idea to the test. [ How Quantum Entanglement Works (Infographic) ]

"At the heart of quantum entanglement is the high degree of correlations in the outcomes of measurements on these pairs [of particles]," David Kaiser, professor of physics at MIT and co-author on the study, said in the statement. "But what if a skeptic or critic insisted these correlations weren't due to these particles acting in a fully quantum mechanical way? We want to address whether there is any other way that those correlations could have snuck in without our having noticed."

Measuring starlight

Every photon of starlight that reaches a telescope has a particular wavelength . In the new study, which was conducted in Vienna, Austria, the researchers set up a couple of telescopes and started collecting photons (the telescopes and detectors were placed on rooftops at the university, as well as the roof of the Austrian National Bank). They selected a reference wavelength, and each photon that hit the telescope would either have a longer or shorter wavelength than that reference point. A photon with a longer wavelength switched the detector to one orientation, and a shorter wavelength switched it to the other orientation.

"With bright stars like these, the number of photons coming in can be like a firehose," Andrew Friedman, an MIT research associate and co-author on the new study, said in the statement. "So we have these very fast detectors that can register detections of cosmic photons on subnanosecond timescales."

The researchers measured about 100,000 pairs of entangled photons with this method, and their results suggested that the particles were truly entangled.

The most distant stars used in the experiment are about 600 light-years away, which means the photons were emitted 600 years ago . If those photons were somehow tied to the state of the entangled photons, that connection would have to have been established 600 years ago, according to the statement.

"This experiment pushes back the latest time at which the conspiracy could have started," Alan Guth, a professor of physics at MIT and another co-author on the new study, said in the statement. "We're saying, in order for some crazy mechanism to simulate quantum mechanics in our experiment, that mechanism had to have been in place 600 years ago to plan for our doing the experiment here today, and to have sent photons of just the right messages to end up reproducing the results of quantum mechanics. So it's very far-fetched."

The study doesn't fully eliminate the possibility of some mysterious force acting on the experiment, but it certainly puts tighter restrictions on how and when such a thing could happen.

"The real estate left over for the skeptics of quantum mechanics has shrunk considerably," Kaiser said. "We haven't gotten rid of it, but we've shrunk it down by 16 orders of magnitude."

Follow Calla Cofield   @callacofield . Follow us   @Spacedotcom ,   Facebook  and   Google+ . Original article on   Space.com .

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Calla Cofield joined Space.com's crew in October 2014. She enjoys writing about black holes, exploding stars, ripples in space-time, science in comic books, and all the mysteries of the cosmos. Prior to joining Space.com Calla worked as a freelance writer, with her work appearing in APS News, Symmetry magazine, Scientific American, Nature News, Physics World, and others. From 2010 to 2014 she was a producer for The Physics Central Podcast. Previously, Calla worked at the American Museum of Natural History in New York City (hands down the best office building ever) and SLAC National Accelerator Laboratory in California. Calla studied physics at the University of Massachusetts, Amherst and is originally from Sandy, Utah. In 2018, Calla left Space.com to join NASA's Jet Propulsion Laboratory media team where she oversees astronomy, physics, exoplanets and the Cold Atom Lab mission. She has been underground at three of the largest particle accelerators in the world and would really like to know what the heck dark matter is. Contact Calla via: E-Mail – Twitter

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China Shatters “Spooky Action at a Distance” Record, Preps for Quantum Internet

Results from the Micius satellite test quantum entanglement, pointing the way toward hackproof global communications

• By Lee Billings  on  June 15, 2017

In a landmark study, a team of Chinese scientists using an experimental satellite tested quantum entanglement over unprecedented distances, beaming entangled pairs of photons to three ground stations across China—each separated by more than 1,200 kilometers. The test verifies a mysterious and long-held tenet of quantum theory and firmly establishes China as the front-runner in a burgeoning “quantum space race” to create a secure, quantum-based global communications network—that is, a potentially unhackable “quantum Internet” that would be of immense geopolitical importance. The findings were published in 2017 in Science .

“China has taken the leadership in quantum communication,” says Nicolas Gisin, a physicist at the University of Geneva, who was not involved in the study. “This demonstrates that global quantum communication is possible and will be achieved in the near future.”

The concept of quantum communications is considered the gold standard for security, in part because any compromising surveillance leaves its imprint on the transmission. Conventional encrypted messages require secret keys to decrypt, but those keys are vulnerable to eavesdropping as they are sent out into the ether. In quantum communications, however, these keys can be encoded in various quantum states of entangled photons—such as their polarization—and these states will be unavoidably altered if a message is intercepted by eavesdroppers. Ground-based quantum communications typically send entangled photon pairs via fiber-optic cables or open air. But collisions with ordinary atoms along the way disrupt the photons’ delicate quantum states, limiting transmission distances to a few hundred kilometers. Sophisticated devices called quantum repeaters—equipped with “quantum memory” modules—could in principle be daisy-chained together to receive, store and retransmit the quantum keys across longer distances, but this task is so complex and difficult that such systems remain largely theoretical.

“A quantum repeater has to receive photons from two different places, then store them in quantum memory, then interfere them directly with each other” before sending further signals along a network, says Paul Kwiat, a physicist at the University of Illinois at Urbana-Champaign, who is unaffiliated with the Chinese team. “But in order to do all that, you have to know you’ve stored them without actually measuring them.” The situation, Kwiat says, is a bit like knowing what you have received in the mail without looking in your mailbox or opening the package inside. “You can shake the package—but that’s difficult to do if what you’re receiving is just photons. You want to make sure you’ve received them, but you don’t want to absorb them. In principle, it’s possible—no question—but it’s very hard to do.”

To form a globe-girdling secure quantum communications network, then, the only available solution is to beam quantum keys through the vacuum of space, then distribute them across tens to hundreds of kilometers using ground-based nodes. Launched into low Earth orbit in 2016 and named after an ancient Chinese philosopher, the 600-kilogram Micius satellite is China’s premiere effort to do just that, as part of the nation’s $100-million Quantum Experiments at Space Scale (QUESS) program.

Micius carries in its heart an assemblage of crystals and lasers that generates entangled photon pairs, then splits and transmits them on separate beams to ground stations in its line of sight on Earth. For the latest test, the three receiving stations were located in the cities of Delingha and Ürümqi—both on the Tibetan Plateau—as well as in the city of Lijiang in China’s far southwest. At 1,203 kilometers, the geographical distance between Delingha and Lijiang was the record-setting stretch over which the entangled photon pairs were transmitted.

For now the system remains mostly a proof of concept because the current reported data-transmission rate between Micius and its receiving stations is too low to sustain practical quantum communications. Of the roughly six million entangled pairs that Micius’s crystalline core produced during each second of transmission, only about one pair per second reached the ground-based detectors after the beams weakened as they passed through Earth’s atmosphere and each receiving station’s light-gathering telescopes. Team leader Jian-Wei Pan—a physicist at the University of Science and Technology of China in Hefei who had pushed and planned for the experiment since 2003—compares the feat with detecting a single photon from a lone match struck by someone standing on the moon. Even so, he says, Micius’s transmission of entangled photon pairs is “a trillion times more efficient than using the best telecommunication fibers.... We have done something that was absolutely impossible without the satellite.” Soon, Pan says, QUESS will launch more practical quantum communications satellites.

Although Pan and his team later used Micius to distribute quantum keys between ground stations in China and Austria in 2017, enabling secure intercontinental communications, their initial demonstration instead aimed to achieve a simpler task: proving Albert Einstein wrong.

Einstein famously derided as “spooky action at a distance” one of the most bizarre elements of quantum theory—the way that measuring one member of an entangled pair of particles seems to instantaneously change the state of its counterpart, even if that counterpart particle is on the other side of the galaxy. This was abhorrent to Einstein because it suggests information might be transmitted between the particles faster than light, breaking the universal speed limit set by his theory of special relativity. Instead, he and others posited, perhaps the entangled particles somehow shared “hidden variables” that are inaccessible to experiment but would determine the particles’ subsequent behavior when measured. In 1964 physicist John Bell devised a way to test Einstein’s idea, calculating a limit that physicists could statistically measure for how much hidden variables could possibly correlate with the behavior of entangled particles. If experiments showed this limit to be exceeded, then Einstein’s idea of hidden variables would be incorrect.

Ever since the 1970s “Bell tests” by physicists across ever larger swaths of spacetime have shown that Einstein was indeed mistaken and that entangled particles do in fact surpass Bell’s strict limits. One definitive test occurred in the Netherlands in 2015, when a team at Delft University of Technology closed several potential “loopholes” that had plagued past experiments and offered slim but significant opportunities for the influence of hidden variables to slip through. That test, though, involved separating entangled particles by scarcely more than a kilometer. With Micius’s transmission of entangled photons between widely separated ground stations, Pan’s team performed a Bell test at distances 1,000 times greater. Just as before, their results confirm that Einstein was wrong. The quantum realm remains a spooky place—although no one yet understands why.

“Of course, no one who accepts quantum mechanics could possibly doubt that entanglement can be created over that distance—or over any distance—but it’s still nice to see it made concrete,” says Scott Aaronson, a physicist at the University of Texas at Austin. “Nothing we knew suggested this goal was unachievable. The significance of this news is not that it was unexpected or that it overturns anything previously believed but simply that it’s a satisfying culmination of years of hard work.”

That work largely began in the 1990s, when Pan, leader of the Chinese team, was a graduate student in the laboratory of physicist Anton Zeilinger when he was at the University of Innsbruck in Austria. Zeilinger was Pan’s Ph.D. adviser, and they collaborated closely to test and further develop ideas for quantum communication. Pan returned to China to start his own lab in 2001, and Zeilinger started one as well at the Austrian Academy of Sciences in Vienna. For the next seven years they would compete fiercely to break records for transmitting entangled photon pairs across ever wider gaps, and in ever more extreme conditions, in ground-based experiments. All the while each man lobbied his respective nation’s space agency to green-light a satellite that could be used to test the technique from space. But Zeilinger’s proposals perished in a bureaucratic swamp at the European Space Agency, whereas Pan’s were quickly embraced by the China National Space Administration. Ultimately Zeilinger chose to collaborate again with his old pupil rather than compete against him; today the Austrian Academy of Sciences is a crucial partner in the QUESS program.

“I am happy that the Micius works so well,” Zeilinger says. “But one has to realize that it is a missed opportunity for Europe and others, too.”

For years now other researchers and institutions have been scrambling to catch up, pushing governments for more funding for further experiments on the ground and in space—and many of them see Micius’s success as the catalytic event they have been waiting for. “This is a major milestone because if we are ever to have a quantum Internet in the future, we will need to send entanglement over these sorts of long distances,” says Thomas Jennewein, a physicist at the University of Waterloo in Ontario, who was not involved with the study. “This research is groundbreaking for all of us in the community—everyone can point to it and say, ‘See, it does work!’”

Jennewein and his collaborators are pursuing a space-based approach from the ground up, partnering with the Canadian Space Agency to plan a smaller, simpler satellite that could eventually act as a “universal receiver” and redistribute entangled photons beamed up from ground stations. At the National University of Singapore, an international collaboration led by physicist Alexander Ling has already launched cheap shoebox-size CubeSats to create, study and perhaps even transmit photon pairs that are “correlated”—a situation just shy of full entanglement. And in the U.S., Kwiat is using nasa funding to develop a device that could someday test quantum communications using “hyperentanglement” (the simultaneous entanglement of photon pairs in multiple ways) onboard the International Space Station.

Perhaps most significantly, a team led by Gerd Leuchs and Christoph Marquardt of the Max Planck Institute for the Science of Light in Erlangen, Germany, is developing quantum communications protocols for commercially available laser systems already in space onboard the European Copernicus and SpaceDataHighway satellites. Using one of these systems, the team successfully encoded and sent simple quantum states to ground stations using photons beamed from a satellite in geostationary orbit, some 38,000 kilometers above Earth. This approach, Marquardt explains, does not rely on entanglement and is very different from that of QUESS—but it could, with minimal upgrades, nonetheless be used to distribute quantum keys for secure communications. Their results appeared in Optica .

“Our purpose is really to find a shortcut into making things like quantum-key distribution with satellites economically viable and employable, pretty fast and soon,” Marquardt says. “[Engineers] invested 20 years of hard work making these systems, so it’s easier to upgrade them than to design everything from scratch.... It is a very good advantage if you can rely on something that is already qualified in space because space qualification is very complicated. It usually takes five to 10 years just to develop that.”

Marquardt and others suspect, however, that this field could be much further advanced than has been publicly acknowledged, with developments possibly hidden behind veils of official secrecy in the U.S. and elsewhere. It may be that the era of quantum communication is already upon us. “Some colleague of mine made the joke that ‘the silence of the U.S. is very loud,’” Marquardt says. “They had some very good groups concerning free-space satellites and quantum-key distribution at Los Alamos [National Laboratory] and other places, and suddenly they stopped publishing. So we always say there are two reasons that they stopped publishing: either it didn’t work, or it worked really well!”

MORE TO EXPLORE

Chinese Satellite Is 1 Giant Step for the Quantum Internet. Elizabeth Gibney, ScientificAmerican.com; July 27, 2016.

Quantum-Limited Measurements of Optical Signals from a Geostationary Satellite. Kevin Günthner et al. in Optica, Vol. 4, No. 6, pages 611–616; June 2017.

Satellite-Based Entanglement Distribution over 1200 Kilometers. Juan Yin et al. in Science , Vol. 356, pages 1140–1144; June 16, 2017.

ABOUT THE AUTHOR(S)

Lee Billings is a science journalist specializing in astronomy, physics, planetary science, and spaceflight, and is a senior editor at Scientific American . He is the author of a critically acclaimed book, Five Billion Years of Solitude: the Search for Life Among the Stars , which in 2014 won a Science Communication Award from the American Institute of Physics. In addition to his work for Scientific American , Billings's writing has appeared in the New York Times , the Wall Street Journal , the Boston Globe , Wired , New Scientist , Popular Science , and many other publications. A dynamic public speaker, Billings has given invited talks for NASA's Jet Propulsion Laboratory and Google, and has served as M.C. for events held by National Geographic , the Breakthrough Prize Foundation, Pioneer Works, and various other organizations. Billings joined Scientific American in 2014, and previously worked as a staff editor at SEED magazine. He holds a B.A. in journalism from the University of Minnesota.  Follow Lee Billings on Twitter  Credit: Nick Higgins

Recent Articles by Lee Billings

• Here's What 'Oppenheimer' Gets Right--And Wrong--About Nuclear History
• The Universe Is Abuzz with Giant Gravitational Waves, and Scientists Just Heard Them (Maybe)
• We Live in the Rarest Type of Planetary System

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Quantum Physics

Title: testing spooky action at a distance.

Abstract: In science, one observes correlations and invents theoretical models that describe them. In all sciences, besides quantum physics, all correlations are described by either of two mechanisms. Either a first event influences a second one by sending some information encoded in bosons or molecules or other physical carriers, depending on the particular science. Or the correlated events have some common causes in their common past. Interestingly, quantum physics predicts an entirely different kind of cause for some correlations, named entanglement. This new kind of cause reveals itself, e.g., in correlations that violate Bell inequalities (hence cannot be described by common causes) between space-like separated events (hence cannot be described by classical communication). Einstein branded it as spooky action at a distance. A real spooky action at a distance would require a faster than light influence defined in some hypothetical universally privileged reference frame. Here we put stringent experimental bounds on the speed of all such hypothetical influences. We performed a Bell test during more than 24 hours between two villages separated by 18 km and approximately east-west oriented, with the source located precisely in the middle. We continuously observed 2-photon interferences well above the Bell inequality threshold. Taking advantage of the Earth's rotation, the configuration of our experiment allowed us to determine, for any hypothetically privileged frame, a lower bound for the speed of this spooky influence. For instance, if such a privileged reference frame exists and is such that the Earth's speed in this frame is less than 10^-3 that of the speed of light, then the speed of this spooky influence would have to exceed that of light by at least 4 orders of magnitude.

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