The cutest character from the new "Star Wars" film has a little mystery to it.

Unbeknownst to many, BB-8 wasn't computer generated for "Star Wars: The Force Awakens." It's a fully functioning robot, as seen when it debuted at Star Wars Celebration 2015 in April.

Unlike BB-8's predecessor, R2-D2, BB-8 is spherical with a floating head that stays in place as the body rotates to move. So how exactly does it work?

No, unfortunately, it's not like this:

 But rather, more likely like this:

 In fact, there's a whole website dedicated to piecing together how BB-8 works. The website's authors, Carlos Sánchez and Emilio Gelardo, think the mechanisms in the spherical part work much like the Sphero ball, a robotic ball that uses a gyroscope to figure out which was is up. The Sphero ball technology is what's being used in the BB-8 toys.

The gif above, taken from Sánchez and Gelardo's website, shows a bit more complex set-up than the two-wheeled Sphero. There's also a curved bar, which looks like it would aid the movement of the BB-8's head. And that's truly the coolest part. 

As the BB-8 skims across the sandy surface of desert planets, (yes, that would cause a traction problem), its head manages to stay put or adjust depending on the direction it's facing.

Sánchez and Gelardo think they have that figured out too. They came across a patent Disney owns that looks curiously like the BB-8 droid. That's where they came up with the curved bar (they call it a dynamic mast), which holds on to the magnets inside the sphere that can connect with the roller magnets in the head. Voila, a floating head that can stay in the right position even as the body spins and spins.

"This, if you think about it, makes the whole mechanism behave like a miniature Segway,"they wrote. "The arm can rotate and, according to the patent, magnetically interact with an external element."

Though they don't know for sure, this theory seems like a pretty good bet for how the BB-8 works. If the confirmed mechanisms ever leak, we'll be sure to keep you posted. 

CHECK OUT: Neil deGrasse Tyson just pointed out a huge problem with the BB-8 droid from 'Star Wars'

NEXT: 8 burning questions everyone has about 'Star Wars: The Force Awakens' and the most logical answers

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Is one human year equal to seven dog years? Can you kill someone by throwing a penny off of the Empire State Building? Do Twinkies last forever? We answer the important questions.

Produced by Christine Nguyen. Original reporting by Jessica Orwig, Jennifer Welsh and Robert Ferris.

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Why does life exist?

Popular hypotheses credit a primordial soup, a bolt of lightning, and a colossal stroke of luck.

But if a provocative new theory is correct, luck may have little to do with it. Instead, according to the physicist proposing the idea, the origin and subsequent evolution of life follow from the fundamental laws of nature and “should be as unsurprising as rocks rolling downhill.”

From the standpoint of physics, there is one essential difference between living things and inanimate clumps of carbon atoms: The former tend to be much better at capturing energy from their environment and dissipating that energy as heat.

Jeremy England, an assistant professor at the Massachusetts Institute of Technology, has derived a mathematical formula that he believes explains this capacity.

The formula, based on established physics, indicates that when a group of atoms is driven by an external source of energy (like the sun or chemical fuel) and surrounded by a heat bath (like the ocean or atmosphere), it will often gradually restructure itself in order to dissipate increasingly more energy. This could mean that, under certain conditions, matter inexorably acquires the key physical attribute associated with life.

“You start with a random clump of atoms, and if you shine light on it for long enough, it should not be so surprising that you get a plant,” England said.

England’s theory is meant to underlie, rather than replace, Darwin’s theory of evolution by natural selection, which provides a powerful description of life at the level of genes and populations. “I am certainly not saying that Darwinian ideas are wrong,” he explained. “On the contrary, I am just saying that from the perspective of the physics, you might call Darwinian evolution a special case of a more general phenomenon.”

His idea, detailed in a paper and further elaborated in a talk he delivered at universities around the world, has sparked controversy among his colleagues, who see it as either tenuous or a potential breakthrough, or both.

England has taken “a very brave and very important step,” said Alexander Grosberg, a professor of physics at New York University who has followed England’s work since its early stages. The “big hope” is that he has identified the underlying physical principle driving the origin and evolution of life, Grosberg said.

“Jeremy is just about the brightest young scientist I ever came across,” said Attila Szabo, a biophysicist in the Laboratory of Chemical Physics at the National Institutes of Health who corresponded with England about his theory after meeting him at a conference. “I was struck by the originality of the ideas.”

Others, such as Eugene Shakhnovich, a professor of chemistry, chemical biology and biophysics at Harvard University, are not convinced. “Jeremy’s ideas are interesting and potentially promising, but at this point are extremely speculative, especially as applied to life phenomena,” Shakhnovich said.

England’s theoretical results are generally considered valid. It is his interpretation — that his formula represents the driving force behind a class of phenomena in nature that includes life — that remains unproven. But already, there are ideas about how to test that interpretation in the lab.

“He’s trying something radically different,” said Mara Prentiss, a professor of physics at Harvard who is contemplating such an experiment after learning about England’s work. “As an organizing lens, I think he has a fabulous idea. Right or wrong, it’s going to be very much worth the investigation.”

At the heart of England’s idea is the second law of thermodynamics, also known as the law of increasing entropy or the “arrow of time.”

Hot things cool down, gas diffuses through air, eggs scramble but never spontaneously unscramble; in short, energy tends to disperse or spread out as time progresses.

Entropy is a measure of this tendency, quantifying how dispersed the energy is among the particles in a system, and how diffuse those particles are throughout space. It increases as a simple matter of probability: There are more ways for energy to be spread out than for it to be concentrated.

Thus, as particles in a system move around and interact, they will, through sheer chance, tend to adopt configurations in which the energy is spread out.

Eventually, the system arrives at a state of maximum entropy called “thermodynamic equilibrium,” in which energy is uniformly distributed. A cup of coffee and the room it sits in become the same temperature, for example.

As long as the cup and the room are left alone, this process is irreversible. The coffee never spontaneously heats up again because the odds are overwhelmingly stacked against so much of the room’s energy randomly concentrating in its atoms.

Although entropy must increase over time in an isolated or “closed” system, an “open” system can keep its entropy low — that is, divide energy unevenly among its atoms — by greatly increasing the entropy of its surroundings. In his influential 1944 monograph “What Is Life?” the eminent quantum physicist Erwin Schrödinger argued that this is what living things must do. A plant, for example, absorbs extremely energetic sunlight, uses it to build sugars, and ejects infrared light, a much less concentrated form of energy. The overall entropy of the universe increases during photosynthesis as the sunlight dissipates, even as the plant prevents itself from decaying by maintaining an orderly internal structure.

Life does not violate the second law of thermodynamics, but until recently, physicists were unable to use thermodynamics to explain why it should arise in the first place. In Schrödinger’s day, they could solve the equations of thermodynamics only for closed systems in equilibrium. In the 1960s, the Belgian physicist Ilya Prigogine made progress on predicting the behavior of open systems weakly driven by external energy sources (for which he won the 1977 Nobel Prize in chemistry). But the behavior of systems that are far from equilibrium, which are connected to the outside environment and strongly driven by external sources of energy, could not be predicted.

This situation changed in the late 1990s, due primarily to the work of Chris Jarzynski, now at the University of Maryland, and Gavin Crooks, now at Lawrence Berkeley National Laboratory. Jarzynski and Crooks showed that the entropy produced by a thermodynamic process, such as the cooling of a cup of coffee, corresponds to a simple ratio: the probability that the atoms will undergo that process divided by their probability of undergoing the reverse process (that is, spontaneously interacting in such a way that the coffee warms up). As entropy production increases, so does this ratio: A system’s behavior becomes more and more “irreversible.” The simple yet rigorous formula could in principle be applied to any thermodynamic process, no matter how fast or far from equilibrium. “Our understanding of far-from-equilibrium statistical mechanics greatly improved,” Grosberg said. England, who is trained in both biochemistry and physics, started his own lab at MIT two years ago and decided to apply the new knowledge of statistical physics to biology.

Using Jarzynski and Crooks’ formulation, he derived a generalization of the second law of thermodynamics that holds for systems of particles with certain characteristics: The systems are strongly driven by an external energy source such as an electromagnetic wave, and they can dump heat into a surrounding bath. This class of systems includes all living things. England then determined how such systems tend to evolve over time as they increase their irreversibility. “We can show very simply from the formula that the more likely evolutionary outcomes are going to be the ones that absorbed and dissipated more energy from the environment’s external drives on the way to getting there,” he said. The finding makes intuitive sense: Particles tend to dissipate more energy when they resonate with a driving force, or move in the direction it is pushing them, and they are more likely to move in that direction than any other at any given moment.

“This means clumps of atoms surrounded by a bath at some temperature, like the atmosphere or the ocean, should tend over time to arrange themselves to resonate better and better with the sources of mechanical, electromagnetic or chemical work in their environments,” England explained.

Self-replication (or reproduction, in biological terms), the process that drives the evolution of life on Earth, is one such mechanism by which a system might dissipate an increasing amount of energy over time.

As England put it, “A great way of dissipating more is to make more copies of yourself.”

In a paper in the Journal of Chemical Physics, he reported the theoretical minimum amount of dissipation that can occur during the self-replication of RNA molecules and bacterial cells, and showed that it is very close to the actual amounts these systems dissipate when replicating.

He also showed that RNA, the nucleic acid that many scientists believe served as the precursor to DNA-based life, is a particularly cheap building material. Once RNA arose, he argues, its “Darwinian takeover” was perhaps not surprising.

The chemistry of the primordial soup, random mutations, geography, catastrophic events and countless other factors have contributed to the fine details of Earth’s diverse flora and fauna. But according to England’s theory, the underlying principle driving the whole process is dissipation-driven adaptation of matter.

This principle would apply to inanimate matter as well. “It is very tempting to speculate about what phenomena in nature we can now fit under this big tent of dissipation-driven adaptive organization,” England said. “Many examples could just be right under our nose, but because we haven’t been looking for them we haven’t noticed them.”

Scientists have already observed self-replication in nonliving systems. According to new research led by Philip Marcus of the University of California, Berkeley, and reported in Physical Review Letters in August, vortices in turbulent fluids spontaneously replicate themselves by drawing energy from shear in the surrounding fluid. And in a paper in Proceedings of the National Academy of Sciences, Michael Brenner, a professor of applied mathematics and physics at Harvard, and his collaborators present theoretical models and simulations of microstructures that self-replicate. These clusters of specially coated microspheres dissipate energy by roping nearby spheres into forming identical clusters. “This connects very much to what Jeremy is saying,” Brenner said.

Besides self-replication, greater structural organization is another means by which strongly driven systems ramp up their ability to dissipate energy. A plant, for example, is much better at capturing and routing solar energy through itself than an unstructured heap of carbon atoms. Thus, England argues that under certain conditions, matter will spontaneously self-organize. This tendency could account for the internal order of living things and of many inanimate structures as well. “Snowflakes, sand dunes and turbulent vortices all have in common that they are strikingly patterned structures that emerge in many-particle systems driven by some dissipative process,” he said. Condensation, wind and viscous drag are the relevant processes in these particular cases.

“He is making me think that the distinction between living and nonliving matter is not sharp,” said Carl Franck, a biological physicist at Cornell University, in an email. “I’m particularly impressed by this notion when one considers systems as small as chemical circuits involving a few biomolecules.”

England’s bold idea will likely face close scrutiny in the coming years.

He is currently running computer simulations to test his theory that systems of particles adapt their structures to become better at dissipating energy. The next step will be to run experiments on living systems.

Prentiss, who runs an experimental biophysics lab at Harvard, says England’s theory could be tested by comparing cells with different mutations and looking for a correlation between the amount of energy the cells dissipate and their replication rates.

“One has to be careful because any mutation might do many things,” she said. “But if one kept doing many of these experiments on different systems and if [dissipation and replication success] are indeed correlated, that would suggest this is the correct organizing principle.”

Brenner said he hopes to connect England’s theory to his own microsphere constructions and determine whether the theory correctly predicts which self-replication and self-assembly processes can occur — “a fundamental question in science,” he said.

Having an overarching principle of life and evolution would give researchers a broader perspective on the emergence of structure and function in living things, many of the researchers said. “Natural selection doesn’t explain certain characteristics,” said Ard Louis, a biophysicist at Oxford University, in an email. These characteristics include a heritable change to gene expression called methylation, increases in complexity in the absence of natural selection, and certain molecular changes Louis has recently studied.

If England’s approach stands up to more testing, it could further liberate biologists from seeking a Darwinian explanation for every adaptation and allow them to think more generally in terms of dissipation-driven organization. They might find, for example, that “the reason that an organism shows characteristic X rather than Y may not be because X is more fit than Y, but because physical constraints make it easier for X to evolve than for Y to evolve,” Louis said.

“People often get stuck in thinking about individual problems,” Prentiss said.  Whether or not England’s ideas turn out to be exactly right, she said, “thinking more broadly is where many scientific breakthroughs are made.”

Emily Singer contributed reporting.

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For the first time, astronomers have observed bursts of visible light being released by a black hole as it swallows matter from nearby stars.

These flashes of light, which lasted between several minutes to a few hours, were seen coming from a black hole in the Cygnus constellation, located about 7,800 light-years away from Earth. Incredibly, some of the flashes were so bright, the team says amateur astronomers could see them with a modest 20-cm telescope.

"We find that activity in the vicinity of a black hole can be observed in optical light at low luminosity for the first time," astronomer and lead researcher, Mariko Kimura from Kyoto University in Japan, told Charles Q. Choi at Space.com.

"These findings suggest that we can study physical phenomena that occur in the vicinity of the black hole using moderate optical telescopes without high-spec X-ray or gamma-ray telescopes."

Nothing - including light - can escape a black hole once it’s fallen in, but the process of swallowing gas, dust, or ripping apart whole stars can cause the formation of an accretion disk near the event horizon. These disks can thrust streams of plasma called relativistic jets across the entire length of a galaxy, while hitting temperatures of 10 million degrees Celsius (18 million degrees Fahrenheit) or more.

This insane heat can cause a black hole accretion disk to give off an incredibly bright glow, which is what Kimura and her team observed when they focused in on V404 Cygni - an active black hole in the Cygnus constellation that reactivated on 15 June 2015 after 26 years of dormancy.

First detected by NASA's Swift space telescope, the event was then tracked by the Japanese researchers, who called on scientists from 26 locations around the world to point their optical telescopes at V404 Cygni.

For two weeks, the astronomers were able to observe flashes of light being released by the newly active V404 Cygni, which is one of the closest known black holes to Earth. It was woken up when the gravitational pull of its partner star pulled the two in too close, causing the black hole to strip away the surface matter of the star, before the whole thing fell in to release an incredible burst of radiation.

For the first time, astronomers have witnessed the light produced by this event using an optical telescope.

Publishing in Nature today, the team hypothesizes that the light originates from X-rays produced in the centre of the accretion disk, and these X-rays irradiate and heat up the outer region of the disk, which causes it to emit optical rays.

While more research is needed to confirm this, it’s beyond exciting to think of how much more we stand to learn about black holes now that we have a new way of observing them - and it’s something anyone can help with if they have a good telescope at home.

"We're very pleased that our international observation network was able to come together to document this rare event,"said co-author, Daisuku Nogami.

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The shapes of the paper snowflakes you may have cut out as a kid actually exist in nature. 

If a snowstorm comes under just the right conditions, giant, picture-perfect snowflakes can form.

Kenneth Libbrecht, a physics professor at Caltech, has studied snow crystal formation for years.

Since he can't see many snowflakes in Southern California, Libbrecht travels to ideal locations like Northern Ontario to photograph them in the wild. He even grows his own in the lab. 

Libbrecht has compiled a guide to different snowflake shapes, of which there are over 120. 

Giant, gorgeous snowflakes, Libbrecht told Tech Insider, are most often classified as "stellar dentrites." The ideal conditions to see these are when it's particularly cold out: around 5 degrees Fahrenheit. 

"I'm always looking for these conditions where the clouds are really low, almost like fog, and the crystals are forming very close to the ground — that's when you get the really nice ones," he said. "And you want a light snowfall; wind is not very good. Cold, calm and low clouds — that’s the recipe. And you don't get that very often."

If you're lucky enough to get the perfect snowfall this winter, head outside with a magnifying glass. You'd be amazed what nature can make. 

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Physicists have searched for ripples in the fabric of spacetime for nearly 100 years, ever since Albert Einstein's 1915 theory of relativity predicted they exist.

These ripples, called gravitational waves, happen when a massive celestial object suddenly moves, like when a star explodes, or when two massive objects collide, like the merging of two black holes.

These cataclysmic disturbances create ripples through space and time — the same way a rain drop can make ripples when it falls on the surface of a lake.

The Laser Interferometer Gravitational-Wave Observatory (LIGO) has been searching for these gravitational waves since 2002 with no luck. But a more powerful, advanced LIGO — about three times more sensitive than the original detector — started operating in September 2015.

And now a rumor is circulating that physicists at the new and improved LIGO have finally detected the elusive waves. If it's true, it will be one of the most important discoveries in physics in the last century.

The rumor first cropped up just a few weeks after the advanced LIGO started operating. Cosmologist Lawrence Krauss tweeted that LIGO may have found the elusive waves at last:

As promised, Krauss followed up today (January 11), and it seems the rumor has held true:

But the official word from LIGO is that there's no news to report yet.

"We will share results when ready but have nothing yet — it takes months to analyze the data, interpret results and review them," Gabriela Gonzalez, physicist and spokesperson for LIGO, told Tech Insider in an email.

Some have speculated that the rumor might be the result of a drill — a false positive signal stuck into the LIGO data as a kind of training exercise for the scientists analyzing it.

Whoever Krauss' source is says that's not the case though:

Others have taken to Twitter to express their frustration that the rumor exists at all.

As Jennifer Ouellette reported in Gizmodo, Loyola University physicist Robert McNees tweeted that he doubts the rumor came from scientists at LIGO:

The discovery of gravity waves would further confirm the theory of inflation — the idea that in the first few moments the universe existed, it underwent a rapid and mind-bogglingly huge expansion. That kind of rapid expansion would almost certainly leave behind ripples through spacetime.

But the most important part is that inflation is an idea that falls under quantum physics (the laws that govern tiny subatomic particles), while gravity waves are part of classical physics (the laws that govern larger objects). The discovery of gravity waves could establish a link between quantum physics and classical physics and get us one step closer to a grand "theory of everything" in physics.

Tech Insider has reached out to Krauss and other scientists at LIGO and we'll update this post if we hear back.

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On Monday, theoretical physicist Laurence Krauss sent the scientific community on Twitter reeling when he suggested that researchers may have detected, for the first time, an astrophysical phenomenon called gravitational waves.

Right now, the rumor is just that. The scientists to which the rumor refers work at the Laser Interferometer Gravitational-Wave Observatory (LIGO) and told Business Insider that there is no basis for such a claim, yet.

"We are still taking data, and we won't finish analyzing and reviewing results until at least a month or two later," Gabriela Gonzalez, LIGO spokesperson and Louisiana State University physics and astronomy professor, told Business Insider.

She added: "The instruments are working great, but ... I don't have any news with analysis results to share, yet."

But what if the rumor turns out to be real? Well, the prospect of what that would mean for science is what earned Krauss's Tweet 4,250% more retweets than his usual 40 or so — overnight.

What are gravitational waves and why do they matter?

Albert Einstein first predicted the existence of gravitational waves in 1916.

According to his theory of general relativity, a number of incredibly powerful cosmic systems across the universe will generate measurable ripples in the fabric of space-time called gravitational waves.

One example is two black holes orbiting one another that are eventually destined to collide.

When a smaller black hole meets a larger one, the two attract one another through tremendous gravitational forces. As the smaller black hole inches toward its inevitable doom, is accelerates through space at an ever-increasing rate toward the larger black hole, and, in so doing, generates gravitational waves.

Over 30 years ago, a pair of scientists using the radio telescope in Puerto Rico made the first indirect detection of gravitational waves by observing the behavior of a distant pulsar binary — a pair of rapidly rotating neutron stars (the densest objects in the universe next to black holes). This indirect detection gave fuel for larger projects, like LIGO and the BICEP2 telescope.

In 2014, the BICEP2 team reported the discovery of gravitational waves, but the discovery was later disproved.

To this day, scientists have yet to confirm the existence of gravitational waves with direct, observational evidence, which is why projects like LIGO are so important.

"The detection of gravitational waves would be a game changer for astronomers in the field,"Clifford Will, a distinguished profess of physics at the University of Florida who studied under famed astrophysicist Kip Thorne told Business Insider in 2015. "We would be able to test aspects of general relativity that have not been tested."

Not only that, the ability to observe gravitational waves would open a whole new frontier of astronomy. The same way that astronomers today use light waves to study the universe, they could also use gravitational waves to see cosmic objects — such as colliding black holes — like never before.

How to snag a gravitational wave

LIGO first began sniffing for gravitational waves in 2002. And between 2002 and 2010, the $620 million experiment came up empty handed.

To better the odds, engineers began upgrading LIGO to make it eventually 10 times more sensitive to gravitational waves.

Last September, scientists turned the new-and-improved machine on and began taking data with, what is now called Advanced LIGO.

The way Advanced LIGO works is that it consists of two identical machines that are located 1,865 miles apart — one is in Livingston, Louisiana and the other is in Hanford, Washington.

At each detector, there are two equally-long tunnels with a mirror at the end (one of the mirrors is shown in the image above). Scientists split a laser beam in two and then fire each half down one of the two tunnels. When the beams reflects off the mirror, the two beams should return at the same time, since they're both traveling at the speed of light.

However, if a gravitational wave passes through the detector the same time the laser is traveling through the two tunnels, scientists expect to see a slight difference in time between when the first and second halves of the beam return.

Compared to the length of light waves we see with our eyes, which are micrometers in size (about the width of a human hair), gravitational waves are huge. This is why the distance between each LIGO detector is over 1800 miles, because that's about how long LIGO scientists think the gravitational waves they're searching for should be.

Therefore, if one detector observes a gravitational wave, it should mean the other detector should measure the same signal, offering immediate confirmation that the observation at the first detector isn't a fluke.

Scientists at LIGO aren't taking any chances with this experiment — they don't want another BICEP2 incident. Before they announce a discovery, the data will have been fully vetted twice-over by their expert peers.

But if they do succeed, it will revolutionize astronomy as we know it.

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Rumors are swirling around that scientists working at the Laser Interferometer Gravitational-Wave Observatory (LIGO) in the US have detected gravitational waves, which are ripples in space-time. Is it possible?

After all, in 2014, scientists behind the BICEP2 (Background Imaging of Cosmic Extragalactic Polarization) telescope, made an extraordinary claim that they had detected them.

Initially hailed as the most groundbreaking discovery of the century, it later proved a false alarm: the signal was merely galactic dust.

So are we likely to ever find gravitational waves? And would they really provide irrefutable evidence for the Big Bang? Here are five common myths and misconceptions about gravitational waves.

1. Setbacks are just due to teething problems

It may seem like the search for gravitational waves has only just begun, but it has actually been going on for decades without success.

Gravitational waves are pulsating perturbations, or “ripples” produced in the fabric of space-time as a massive object moves through it. As they propagate, they stretch and squash objects, albeit on subatomic scale. Scientists have therefore been trying to demonstrate the existence of gravitational waves by looking at how nearby objects are affected.

In 1968, American physicist Joseph Weber claimed he had detected gravitational waves in this way using his esoteric detector made up of enormous aluminum cylinders. This was sadly later disproved.

These days, scientists prefer using laser interferometry to search for gravitational waves. It works by splitting a laser beam in two perpendicular directions and sending each down a long vacuum tunnel. The two paths are then reflected back by mirrors to the point they started, where a detector is placed. If the waves are disturbed by gravitational waves on their way, the recombined beams would be different from the original.

Ground-based interferometers, like the Laser Interferometer Gravitational-Wave Observatory (LIGO), have arms that are about four kilometers long. Future space-based interferometers like the Deci-hertz Interferometer Gravitational Wave Observatory (DECIGO) and the Evolved Laser Interferometer Space Antenna (eLISA) will use laser arms spanning up to a million kilometres. These experiments are expected to launch within the next decade.

2. The waves come from the early universe

The strongest sources of gravitational waves are in fact astrophysical processes, which are happening all the time.

The most dominant of these sources is the rotation of pairs of white dwarfs or black holes (so-called “binary systems”). Such pairs are thought to gradually lose energy by emitting gravitational waves. This was demonstrated by the discovery of the famous Hulse-Taylor pulsar in 1974. The pulsar provided indirect evidence of gravitational waves as it was losing energy at a rate which had been predicted by the general theory of relativity (the waves themselves were not seen).

However, scientists are also looking for gravitational waves created shortly after the universe was born, called primordial gravitational waves, which are much more elusive.

3. BICEP2 could one day ‘see’ gravitational waves

One of BICEP2’s goals was try to detect the signature of primordial gravitational waves imprinted in the temperature of the Cosmic Microwave Background (CMB). This radiation contains light that first emerged from the soup of elementary particles when the universe was just 300,000 years old, long before the first stars were born.

When light waves vibrate in a certain direction, we say that it has a specific polarization. If gravitational waves were present at the time when the CMB was born, they should leave behind a unique swirly pattern – a curling in the polarisation of the light – dubbed “B modes”.

Therefore, the B modes are only indirect evidence for gravitational waves. This is an important point: Experiments like BICEP2 will never be able to observe gravitational waves themselves, only the fingerprints they left behind.

Even dusting for these fingerprints is not easy. B-modes are typically masked by much stronger signals from dust emission and an effect called gravitational lensing, which mixes different types of polarisation patterns. Eliminating these and many other contaminants is a most delicate task, often relying on results from other experiments.

This complex challenge will be tackled by the next generation of BICEP-like experiments such as the Atacama Cosmology Telescope (ACT) and its planned successor AdvACT. They will be able to measure CMB to scales beyond the reach of Planck, and would have learned valuable lessons from BICEP in the modeling of dust and other contaminants. The prospects for detecting B-mode within the decade look very promising.

Some have even speculated that space interferometers might be able to detect primordial waves, perhaps by subtracting the waves detected from known astrophysical processes.

4. Gravitational waves would ‘prove’ the Big Bang

The earliest source of gravitational waves is not the Big Bang, but rather cosmological inflation: a period during which the universe underwent a brief flash of exponential expansion just after the Big Bang.

The gravitational waves that BICEP2 claimed to have detected are the by-product of this burst of accelerating expansion of the universe. This is in accordance with general relativity, which predicts that an accelerating body emits gravitational waves (similar to the way an accelerating charge emits electromagnetic waves).

Inflation is currently regarded as the leading model of the early universe. While many key predictions of inflation have been verified, the predicted existence of primordial gravitational waves remains elusive. If they are observed, they will tell us directly about the energy scale at which inflation occurred, bringing us closer to understanding the Big Bang. But they would not prove the Big Bang, which is a mathematical singularity that we are yet to understand.

5. We just need one experiment to detect them

Strong statistical evidence for gravitational waves will certainly require more than one experiment. Like light waves, gravitational waves come in a spectrum of frequencies. The two detection techniques (B-modes and laser interferometry) are searching for waves at different frequencies – 15 orders of magnitude apart.

The simplest theory of inflation predicts a background of primordial gravitational waves with a particular frequency spectrum, in other words we know what the amplitude should be in each frequency. So, if scientists could detect gravitational waves on two of these very different frequencies, it would be strong evidence for inflation that is difficult to refute even by the most hardline skeptic.

So is the search worth it?

It is highly unlikely that the first generation of space interferometers would achieve the sensitivity required to detect primordial gravitational waves. Exactly what such a signal would look like is unknown and could, in principle, be forever out of reach by any future interferometers.

Nevertheless, if we could detect astrophysical gravitational waves directly, this would open up new ways to test the validity of Einstein’s theory of general relativity, which is used to describe gravitation in modern physics. The theory, which has been questioned in recent years), predicts the existence of gravitational waves.

It would also provide new insights into the evolution of stars, galaxies and black holes that we could never get any other way.

Read other articles in our cosmology series here. This article was originally published on September 4, 2015. It was updated on January 12, 2016 to reflect latest developments.

This article was originally published on The Conversation. Read the original article.

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There's a rumor circulating that physicists may have finally discovered ripples in the fabric of spacetime known as "gravitational waves."

Scientists at the Laser Interferometer Gravitational-Wave Observatory (LIGO)— a lab in California that is hunting these waves — have not announced or confirmed anything, though.

"We will share results when ready but have nothing yet — it takes months to analyze the data, interpret results and review them," Gabriela Gonzalez, physicist and spokesperson for LIGO, told Tech Insider in an email.

But the possibility has many scientists thrilled.

Here's why the discovery of gravitational waves would be one of the biggest breakthroughs in physics we've seen in 100 years.

What are gravitational waves?

We know from Albert Einstein's theory of general relativity, published in 1915, that really massive objects can curve the fabric of spacetime around them.

In some ways, it's similar to a bowling ball sinking into and deforming a taut sheet.

So we know spacetime can be warped, and this has some crazy implications.

When a big object suddenly accelerates, for example, it should create ripples through spacetime, called gravitational waves, that are similar to the ripples raindrops create on the surface of a lake.

Physicists think we should be able to spot these ripples when a star explodes, or when two massive objects collide, like when two black holes merge.

How do we detect them?

Physicists have used increasingly complex instruments in hopes of finding them.

LIGO — a huge, L-shaped, laser-powered detector — has been looking for gravitational waves since it opened in 2002, to no avail:

However, a more powerful, advanced LIGO went online in September 2015.

If gravitational ripples are passing by Earth, these instruments should detect disturbances in a very sensitive laser beam setup. (But it's not easy. Even a truck driving by or a farmer plowing a field can disturb the laser beams.)

Where are we looking for them?

Scientists at LIGO are searching around exploding stars, merging black holes, and neutron stars to detect signs of gravitational waves.

Other physicists, like those with the BICEP2 experiment, are searching for signs of gravitational waves from the Big Bang at the edge of the observable universe.

According to the theory of inflation, the universe expanded during the Big Bang at around 100 trillion trillion times in a fraction of a second in its first moments of existence. That kind of cataclysmic disturbance should have created gravitational waves through spacetime.

When the universe began to cool after its rapid inflation, it left behind a faint pattern of temperature fluctuations on the edge of the observable universe. We call it the cosmic microwave background (CMB).

Some physicists think we should be able to spot gravitational waves hiding in the CMB.

What would it mean to find them?

If the new-and-improved LIGO found evidence of gravitational waves, it would be more confirmation that Einstein's theory of relativity is correct.

It would also mean that astronomers finally have a way to track all the objects in the universe that don't emit any kind of visible light, like black holes and neutron stars — and perhaps objects that physicists haven't yet dreamed up or discovered.

And if we find gravitational waves at the edge of the observable universe, it would lend a lot of support to the theory of inflation. It would also give us a better picture of how the universe came to be.

Gravitational waves might also bridge quantum physics (the physics of the very small) with classical physics (the physics of the very large) and get us closer to one unified "theory of everything."

Right now those two branches of science don't get along; physicists can't figure out how the two ideas are supposed to fit together. But if gravitational waves (classical physics) are linked to inflation (quantum physics), we'll know that the two theories can and do work together.

The revelation could usher in a whole new era of physics, astronomical observatories, and perhaps some practical applications, too.

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There's a rumor circulating that physicists have finally detected ripples in the fabric of spacetime — a discovery that could change physics as we know it.

These ripples are called gravitational waves and they emanate from calamitous cosmic events like when a star explodes or when two black holes bump into each other.

Albert Einstein first predicted their existence 100 years ago, and physicists have been hunting for them ever since. Now, some physicists are saying they're hearing whispers that scientists at the Laser Interferometer Gravitational-Wave Observatory (LIGO) have finally detected the waves out in space.

LIGO has not confirmed the rumor is true, and many have their doubts about its veracity since a false alarm has happened before.

But here's how we'd know if LIGO really detected gravitational waves or not, according to an animation created by the lab.

How to detect gravitational waves

LIGO is a huge L-shaped detector that's been hunting gravitational waves since 2002. It relies on a laser to search for them.

The instrument shoots out a laser beam which gets split in two and sent down two 2.5-mile long tubes.

The beams both bounce off mirrors and converge back near the beam splitter. The light waves return at equal length, and line up in such a way that they cancel each other out.

As a result, the light detector part of the instrument doesn't see any light.

But should a gravitational wave come through, it would warp spacetime, and actually make one tube longer and the other shorter. This rhythmic stretching and squeezing would continue until the wave passes.

When this kind of interference happens, the two waves aren't equal lengths when they return, so they don't line up as neatly and no longer cancel each other out.

That means the detector would actually record some flashes of light. So a physicist measuring those changes in brightness would actually be measuring and observing gravitational waves.

LIGO scientists have told reporters that there is a lot of data to comb through and that they'll announce a discovery if and when they detect these signals.

They've made no announcement yet, but at least we know what they're searching for.

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Everything that we see around us — planets, stars, nebulas, and so on — only makes up about 15% of the matter in the universe.

The other 85% of matter is missing. Scientists call this invisible stuff "dark matter" because we can't see it and, so far, no one has directly detected it.

We know dark matter exists only because all the matter that we actually can see can't explain the motion of stars and galaxies in the universe. Not even close.

It's become one of the biggest mysteries in physics. There are a lot of differing theories about what dark matter is made of, and how we might actually find it.

From deep underground caverns to laboratories in space, here are five of the coolest dark matter experiments that are attempting to solve this cosmic mystery.

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No one knows what dark matter is or how to detect it. The race is on to find it.

One lab in South Dakota is hot on the trail. It's called the Large Underground Xenon (LUX) experiment.

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LUX scientists are trying to detect dark matter by catching it bumping into visible matter.

Source

A deeply disturbing and controversial line of thinking has emerged within the physics community.

It's the idea that we are reaching the absolute limit of what we can understand about the world around us through science. 

"The next few years may tell us whether we'll be able to continue to increase our understanding of nature or whether maybe, for the first time in the history of science, we could be facing questions that we cannot answer," Harry Cliff, a particle physicist at the European Organization for Nuclear Research — better known as CERN — said during a recent TED talk in Geneva, Switzerland.

Equally frightening is the reason for this approaching limit, which Cliff says is "Because the laws of physics forbid it."

At the core of Cliff's argument are what he calls the two most dangerous numbers in the universe. These numbers are responsible for all the matter, structure, and life that we witness across the cosmos.

And if these two numbers were even slightly different, says Cliff, the universe would be an empty, lifeless place.

Dangerous Number 1: The strength of the Higgs field

The first dangerous number on Cliff's list is a value that represents the strength of what physicists call the Higgs field, an invisible energy field not entirely unlike other magnetic fields that permeates the cosmos.

As particles swim through the Higgs field, they gain mass to eventually become the protons, neutrons, and electrons comprising all of the atoms that make up you, me, and everything we see around us.

Without it, we wouldn't be here.

We know with near certainty that the Higgs field exists because of a groundbreaking discovery in 2012, when CERN physicists detected a new elementary particle called the Higgs boson. According to theory, you can't have a Higgs boson without a Higgs field.

But there's something mysterious about the Higgs field that continues to perturb physicists like Cliff.

According to Einstein's theory of general relativity and the theory of quantum mechanics — the two theories in physics that drive our understanding of the cosmos on incredibly large and extremely small scales — the Higgs field should be performing one of two tasks, says Cliff.

Either it should be turned off, meaning it would have a strength value of zero and wouldn't be working to give particles mass, or it should be turned on, and, as the theory goes, this "on value" is "absolutely enormous," Cliff says. But neither of those two scenarios are what physicists observe.

"In reality, the Higgs field is just slightly on," says Cliff. "It's not zero, but it's ten thousand trillion times weaker than its fully on value — a bit like a light switch that got stuck just before the 'off' position. And this value is crucial. If it were a tiny bit different, then there would be no physical structure in the universe."

Why the strength of the Higgs field is so ridiculously weak defies understanding. Physicists hope to find an answer to this question by detecting brand new particles at the newly-upgraded particle accelerator at CERN. So far, though, they're still hunting. 

Dangerous Number 2: The strength of dark energy

Cliff's second dangerous number doubles as what physicists have called "the worst theoretical prediction in the history of physics."

This perilous number deals in the depths of deep space and a mind-meltingly complex phenomenon called dark energy. Dark energy, a repulsive force that's responsible for the accelerating expansion of our universe, was first measured in 1998.

Still, "we don't know what dark energy is," Cliff admits. "But the best idea is that it's the energy of empty space itself — the energy of the vacuum."

If this is true, you should be able to sum up all the energy of empty space to get a value representing the strength of dark energy. And although theoretical physicists have done so, there's one gigantic problem with their answer:

"Dark energy should be 10¹²⁰ times stronger than the value we observe from astronomy," Cliff said. "This is a number so mind-boggling huge that it's impossible to get your head around ... this number is bigger than any number in astronomy — it's a thousand trillion trillion trillion times bigger than the number of atoms in the universe. That's a pretty bad prediction."

On the bright side, we're lucky that dark energy is smaller than theorists predict. If it followed our theoretical models, then the repulsive force of dark energy would be so huge that it would literally rip our universe apart. The fundamental forces that bind atoms together would be powerless against it and nothing could ever form — galaxies, stars, planets, and life as we know it would not exist.

On the other hand, it's extremely frustrating that we can't use our current theories of the universe to develop a better measurement of dark energy that agrees with existing observations. Even better than improving our theories would be to find a way that we can understand why the strength of dark energy and the Higgs field is what it is.  

Getting answers could be impossible

Cliff said there is one possible way to get some answers, but we might never have the ability to prove it. 

If we could somehow confirm that our universe is just one in a vast multiverse of billions of other universes, then "suddenly we can understand the weirdly fine tuned values of these two dangerous numbers [because] in most of the multiverse dark energy is so strong that the universe gets torn apart, or the Higgs field is so weak that no atoms can form," Cliff said.  

To prove this, physicists need to discover new particles that would uphold radical theories like string theory, which predicts the existence of a multiverse. Right now, there's only one place in the world that could possibly produce these particles, if they exist, and that's the Large Hadron Collider at CERN. 

And physicists only have two to three years before CERN shuts the LHC down for upgrades. If we haven't found anything by then, Cliff said, it could signal the beginning of the end. 

"We may be entering a new era in physics. An era where there are weird features in the universe that we cannot explain. An era where we have hints that we live in a multiverse that lies frustratingly beyond our reach. An era where we will never be able to answer the question why is there something rather than nothing."

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General Electric makes some ridiculously strong alloys that can withstand incredible pressures and temperatures — stuff you'd want to tool into an airplane engine.

To test how strong these alloys are, GE engineers put them in a heating-and-smashing device called a micro forge, which we first heard about from Digg.

The micro forge, located at GE's Global Research Center in Schenectady, New York, can heat up to the temperature of an active volcano and compresses objects with 100,000 lbs. of pressure.

The company's engineers decided to have a little fun and smash some everyday objects, too. It's pretty amazing to watch what cracks under pressure, and what survives.

This rubber ducky popped, but it was still technically intact.

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This tennis ball bounced right back, unfazed.

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This baseball, filled with cork, exploded.

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It might sound like science fiction, but time travel is completely possible.

Well, at least time travel in one direction.

Back in the early 1900s, Einstein completely changed our understanding of the universe by proposing that we treat space and time as one thing: spacetime. Time just becomes an extra fourth dimension, and one we can move through.

So everything in the universe exists at both a place and a time. But it's impossible to pin down the exact position and time of an object in spacetime because everything in the universe is constantly in motion. We can only measure something from one frame of reference at a moment.

For example, if you're walking 3 miles per hour on a boat, you would clock your speed at just 3 miles per hour. But someone standing on the shore would clock your speed at 3 miles per hour plus whatever speed the boat is going.

We already know how to travel to the future

Time works the same way. The amount of time that passes between two events depends on your point of reference.

The closer something moves to the speed of light, the slower time passes for it. It's a phenomenon called time dilation, and that's why the clock on the International Space Station hurtling around Earth at 17,150 mph, ticks a little slower than clocks on Earth.

If you launched yourself off the Earth in an incredibly high-speed rocket, pulled a U-turn, and came back, you'd be returning to a future Earth. Time will have passed faster for people on Earth than it did for you in your rocket.

Like speed, gravity also messes with the passage of time (another type of time dilation). A huge gravitational field — from something like a black hole, for instance — is so powerful that it bends the fabric of spacetime around it.

If you were able to hang out in that warped spacetime near a black hole, and then return to your spaceship, time will have passed much faster for those on board the ship than it did for you. You're returning to the ship's future.

If you've seen the movie "Interstellar," that exact scenario unfolds. The characters return to the main ship after spending less than a day on a planet near a black hole — but back at the ship, years have passed:

So traveling forward in time is completely compatible with the laws of physics. And it's already technically possible, even though it's only on a fraction of a second scale. 

So why can't we travel back in time?

Traveling to the past is a lot more complicated and would require a lot more energy than we're capable of harnessing.

Some physicists have proposed one could travel to the past through a spacetime tunnel called a wormhole.

Remember how massive objects can curve spacetime around them? It's theoretically possible to fold one of those curves back on itself, creating what's called a closed time-like curve (CTC). Time is on the y-axis and position is on the x-axis:

If you could somehow connect a bunch of those loops together, you could create a tunnel through spacetime that would allow you travel forward and backward in time. Some physicists have proposed this is how Doctor Who's time-traveling TARDIS works.

But in order to create a CTC, it appears that we'd need half of all the matter and energy in the universe, according to a paper published in the Physical Review Letters.

And even if we created a whole tunnel of CTCs, physicists say we'd need a ship that can travel faster than the speed of light to navigate it.

Still, scientists haven't given up hope. Some have devised crazy experiments to search for time travelers, including advertising for and then hosting a "time traveling convention" and hoping that some showed up. (None did.)

So for now, for those interested in revisiting the past, it looks like we're out of luck.

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One of the most persistent theories in the Star Wars universe may have some grounding in reality. We asked Astrophysicist Dave Minton about the 'Endor Holocaust', the fan theory that the exploding Death Star would have annihilated the moon forest of Endor at the end of 'Return of the Jedi'. It turns out to be far worse than anyone expected.

Produced by Corey Protin and Rob Ludacer

Original Reporting by Dave Mosher

Graphics by Skye Gould

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You’ve probably never given cutting a pizza much thought besides the fact that it is something you need to do before you can shove it into your face hole.

Some mathematicians, on the other hand, view the act of cutting a pizza as a geometric dance, a living embodiment of an equation that you can eat afterwards, which is exactly why two researchers from the University of Liverpool have recently published a study about how to cut pizza evenly in weird and overly complicated shapes.

The study, entitled Infinite Families of Monohedral Disk Tilings, explores one question, according to Phys.Org, which the researchers put as: “Can we construct monohedral tilings of the disk such that a neighbourhood of the origin has trivial intersection with at least one tile?”

If that sounds ultra confusing, it’s because it’s phrased in the most complicated way a person could ever phrase a sentence. Basically, in normal people speak, the team is looking for a way to evenly cut up a circle that doesn’t have one intersection in the middle.

In short, no more of this:

To make this topic interesting to everyone with taste buds, the team decided to focus on how to pull it off with a pizza. Since pizza is normally cut in half a bunch of times leaving one intersection of cuts in the middle and results in equal, triangular pieces like the image above, it’s actually the perfect medium to explore different forms of “disk tiling.”

After numerous calculations, the team came up with this:

As you can see, the pizza is now equally cut into curvy “shields” of equal area that has many more intersections than a traditional cut.

However, cutting that crazy design with a dull pizza cutter (they’re always dull) seems like an exercise in frustration that would ruin your dinner.

To pull it off, you cut three curved pieces across the pie. Then, you simply divide the sections in two, which sounds simple but would probably cause a profanity-filled outburst if tried in a group setting.

The real question is what the findings will help us solve on a practical level. After all, the old way of cutting pizza has worked just fine. Most of the time, discoveries like this help us in other aspects of life by solving some small problem that was halting a larger innovation.

This, apparently, isn’t the case here because one of the two researchers, Joel Anthony Haddley, told New Scientist: “I’ve no idea whether there are any applications at all to our work outside of pizza-cutting.” So there you have it, just a new way to cut a pizza.

You can read more about the new study in greater detail over at Phys.Org.

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There's a rumor circulating that physicists may have finally discovered ripples in the fabric of spacetime known as "gravitational waves."

Scientists at the Laser Interferometer Gravitational-Wave Observatory (LIGO)— a lab in California that is hunting these waves — have not announced or confirmed anything, though.

"We will share results when ready but have nothing yet — it takes months to analyze the data, interpret results and review them," Gabriela Gonzalez, physicist and spokesperson for LIGO, told Tech Insider in an email.

But the possibility has many scientists thrilled.

Here's why the discovery of gravitational waves would be one of the biggest breakthroughs in physics we've seen in 100 years.

What are gravitational waves?

We know from Albert Einstein's theory of general relativity, published in 1915, that really massive objects can curve the fabric of spacetime around them.

In some ways, it's similar to a bowling ball sinking into and deforming a taut sheet.

So we know spacetime can be warped, and this has some crazy implications.

When a big object suddenly accelerates, for example, it should create ripples through spacetime, called gravitational waves, that are similar to the ripples raindrops create on the surface of a lake.

Physicists think we should be able to spot these ripples when a star explodes, or when two massive objects collide, like when two black holes merge.

How do we detect them?

Physicists have used increasingly complex instruments in hopes of finding them.

LIGO — a huge, L-shaped, laser-powered detector — has been looking for gravitational waves since it opened in 2002, to no avail:

However, a more powerful, advanced LIGO went online in September 2015.

If gravitational ripples are passing by Earth, these instruments should detect disturbances in a very sensitive laser beam setup. (But it's not easy. Even a truck driving by or a farmer plowing a field can disturb the laser beams.)

Where are we looking for them?

Scientists at LIGO are searching around exploding stars, merging black holes, and neutron stars to detect signs of gravitational waves.

Other physicists, like those with the BICEP2 experiment, are searching for signs of gravitational waves from the Big Bang at the edge of the observable universe.

According to the theory of inflation, the universe expanded during the Big Bang at around 100 trillion trillion times in a fraction of a second in its first moments of existence. That kind of cataclysmic disturbance should have created gravitational waves through spacetime.

When the universe began to cool after its rapid inflation, it left behind a faint pattern of temperature fluctuations on the edge of the observable universe. We call it the cosmic microwave background (CMB).

Some physicists think we should be able to spot gravitational waves hiding in the CMB.

What would it mean to find them?

If the new-and-improved LIGO found evidence of gravitational waves, it would be more confirmation that Einstein's theory of relativity is correct.

It would also mean that astronomers finally have a way to track all the objects in the universe that don't emit any kind of visible light, like black holes and neutron stars — and perhaps objects that physicists haven't yet dreamed up or discovered.

And if we find gravitational waves at the edge of the observable universe, it would lend a lot of support to the theory of inflation. It would also give us a better picture of how the universe came to be.

Gravitational waves might also bridge quantum physics (the physics of the very small) with classical physics (the physics of the very large) and get us closer to one unified "theory of everything."

Right now those two branches of science don't get along; physicists can't figure out how the two ideas are supposed to fit together. But if gravitational waves (classical physics) are linked to inflation (quantum physics), we'll know that the two theories can and do work together.

The revelation could usher in a whole new era of physics, astronomical observatories, and perhaps some practical applications, too.

Join the conversation about this story »

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The shapes of the paper snowflakes you may have cut out as a kid actually exist in nature. 

If a snowstorm comes under just the right conditions, giant, picture-perfect snowflakes can form.

Kenneth Libbrecht, a physics professor at Caltech, has studied snow crystal formation for years.

Since he can't see many snowflakes in Southern California, Libbrecht travels to ideal locations like Northern Ontario to photograph them in the wild. He even grows his own in the lab. 

Libbrecht has compiled a guide to different snowflake shapes, of which there are over 120. 

Giant, gorgeous snowflakes, Libbrecht told Tech Insider, are most often classified as "stellar dentrites." The ideal conditions to see these are when it's particularly cold out: around 5 degrees Fahrenheit. 

"I'm always looking for these conditions where the clouds are really low, almost like fog, and the crystals are forming very close to the ground — that's when you get the really nice ones," he said. "And you want a light snowfall; wind is not very good. Cold, calm and low clouds — that’s the recipe. And you don't get that very often."

If you're lucky enough to get the perfect snowfall this winter, head outside with a magnifying glass. You'd be amazed what nature can make. 

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When Albert Einstein first predicted that light travels the same speed everywhere in our universe, he essentially stamped a speed limit on it: 670,616,629 miles per hour — fast enough to circle the entire Earth eight times every second.

But that's not the entire story. In fact, it's just the beginning.

Before Einstein, mass — the atoms that make up you, me, and everything we see — and energy were treated as separate entities. But in 1905, Einstein forever changed the way physicists view the universe.

Einstein's Special Theory of Relativity permanently tied mass and energy together in the simple yet fundamental equation E=mc². This little equation predicts that nothing with mass can move as fast as light, or faster.

The closest humankind has ever come to reaching the speed of light is inside of powerful particle accelerators like the Large Hadron Collider and the Tevatron.

These colossal machines accelerate subatomic particles to more than 99.99% the speed of light, but as Physics Nobel laureate David Gross explains, these particles will never reach the cosmic speed limit.

To do so would require an infinite amount of energy and, in the process, the object's mass would become infinite, which is impossible. (The reason particles of light, called photons, travel at light speeds is because they have no mass.)

Since Einstein, physicists have found that certain entities can reach superluminal (that means "faster-than-light") speeds and still follow the cosmic rules laid down by special relativity. While these do not disprove Einstein's theory, they give us insight into the peculiar behavior of light and the quantum realm.

The light equivalent of a sonic boom

When objects travel faster than the speed of sound, they generate a sonic boom. So, in theory, if something travels faster than the speed of light, it should produce something like a "luminal boom."

In fact, this light boom happens on a daily basis in facilities around the world — you can see it with your own eyes. It's called Cherenkov radiation, and it shows up as a blue glow inside of nuclear reactors, like in the Advanced Test Reactor at the Idaho National Laboratory in the image to the right.

Cherenkov radiation is named for Soviet scientist Pavel Alekseyevich Cherenkov, who first measured it in 1934 and was awarded the Nobel Physics Prize in 1958 for his discovery.

Cherenkov radiation glows because the core of the Advanced Test Reactor is submerged in water to keep it cool. In water, light travels at 75 % the speed it would in the vacuum of outer space, but the electrons created by the reaction inside of the core travel through the water faster than the light does.

Particles, like these electrons, that surpass the speed of light in water, or some other medium such as glass, create a shock wave similar to the shock wave from a sonic boom.

When a rocket, for example, travels through air, it generates pressure waves in front that move away from it at the speed of sound, and the closer the rocket reaches that sound barrier, the less time the waves have to move out of the object's path. Once it reaches the speed of sound, the waves bunch up creating a shock front that forms a loud sonic boom.

Similarly, when electrons travel through water at speeds faster than light speed in water, they generate a shock wave of light that sometimes shines as blue light, but can also shine in ultraviolet.

While these particles are traveling faster than light does in water, they're not actually breaking the cosmic speed limit of 670,616,629 miles per hour.

When the rules don't apply

Keep in mind that Einstein's Special Theory of Relativity states that nothing with mass can go faster than the speed of light, and as far as physicists can tell, the universe abides by that rule. But what about something without mass?

Photons, by their very nature, cannot exceed the speed of light, but particles of light are not the only massless entity in the universe. Empty space contains no material substance and therefore, by definition, has no mass.

"Since nothing is just empty space or vacuum, it can expand faster than light speed since no material object is breaking the light barrier," said theoretical astrophysicist Michio Kaku on Big Think. "Therefore, empty space can certainly expand faster than light."

This is exactly what physicists think happened immediately after the Big Bang during the epoch called inflation, which was first hypothesized by physicists Alan Guth and Andrei Linde in the 1980s. Within a trillionth of a trillionth of a second, the universe repeatedly doubled in size and as a result, the outer edge of the universe expanded very quickly, much faster than the speed of light.

Quantum entanglement makes the cut

Quantum entanglement sounds complex and intimidating but at a rudimentary level entanglement is just the way subatomic particles communicate with each other.

"If I have two electrons close together, they can vibrate in unison, according to the quantum theory," Kaku explains on Big Think. Now, separate those two electrons so that they're hundreds or even thousands of light years apart, and they will keep this instant communication bridge open.

"If I jiggle one electron, the other electron 'senses' this vibration instantly, faster than the speed of light. Einstein thought that this therefore disproved the quantum theory, since nothing can go faster than light," Kaku wrote.

In fact, in 1935, Einstein, Boris Podolsky and Nathan Rosen, attempted to disprove quantum theory with a thought experiment on what Einstein referred to as "spooky actions at a distance."

Ironically, their paper laid the foundation for what today is called the EPR (Einstein-Podolsky-Rosen) paradox, a paradox that describes this instantaneous communication of quantum entanglement — an integral part of some of the world's most cutting-edge technologies, like quantum cryptography.

Dreaming of wormholes

Since nothing with mass can travel faster than light, you can kiss interstellar travel goodbye — at least, in the classical sense of rocketships and flying.

Although Einstein trampled over our aspirations of deep-space roadtrips with his Theory of Special Relativity, he gave us a new hope for interstellar travel with his General Theory of Relativity in 1915.

While Special Relativity wed mass and energy, General Relativity wove space and time together.

"The only viable way of breaking the light barrier may be through General Relativity and the warping of space time," Kaku writes. This warping is what we colloquially call a "wormhole," which theoretically would let something travel vast distances instantaneously, essentially enabling us to break the cosmic speed limit by traveling great distances in a very short amount of time.

In 1988, theoretical physicist Kip Thorne — the science consultant and executive producer for the recent film "Interstellar"— used Einstein's equations of General Relativity to predict the possibility of wormholes that would forever be open for space travel.

But in order to be traversable, these wormholes need some strange, exotic matter holding them open.

"Now it is an amazing fact that exotic matter can exist, thanks to weirdnesses in the laws of quantum physics," Thorne writes in his book "The Science of Interstellar."

And this exotic matter has even been made in laboratories here on Earth, but in very tiny amounts. When Thorne proposed his theory of stable wormholes in 1988 he called upon the physics community to help him determine if enough exotic matter could exist in the universe to support the possibility of a wormhole.

"This triggered a lot of research by a lot of physicists; but today, nearly thirty years later, the answer is still unknown." Thorne writes. At the moment, it's not looking good, "But we are still far from a final answer," he concludes.

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Everything that we see around us — planets, stars, nebulas, and so on — only makes up about 15% of the matter in the universe.

The other 85% of matter is missing. Scientists call this invisible stuff "dark matter" because we can't see it and, so far, no one has directly detected it.

We know dark matter exists only because all the matter that we actually can see can't explain the motion of stars and galaxies in the universe. Not even close.

It's become one of the biggest mysteries in physics. There are a lot of differing theories about what dark matter is made of, and how we might actually find it.

From deep underground caverns to laboratories in space, here are five of the coolest dark matter experiments that are attempting to solve this cosmic mystery.

No one knows what dark matter is or how to detect it. The race is on to find it.

One lab in South Dakota is hot on the trail. It's called the Large Underground Xenon (LUX) experiment.

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LUX scientists are trying to detect dark matter by catching it bumping into visible matter.

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