Space-time loops may explain black holes

Explaining black holes

Physics cannot describe what happens inside a black hole. There, current theories break down, and general relativity collides with quantum mechanics, creating what's called a singularity, or a point at which the equations spit out infinities.

But some advanced physics theories are trying to bridge the gap between general relativity and quantum mechanics, to understand what's truly going on inside the densest objects in the universe. Recently, scientists applied a theory called loop quantum gravity to the case of black holes, and found that inside these objects, space and time may be extremely curved, but that gravity there is not infinite, as general relativity predicts.

This was the first time scientists have applied the full loop quantum gravity theory to black holes, and the results were encouraging, researchers said.

"What they have done is a major step, because they have been able to provide a much more complete description of what really happens near the black hole singularity using loop quantum gravity," said Abhay Ashtekar, a physicist who studies loop quantum gravity at Pennsylvania State University, who was not involved in the new research."We still don't have a clear picture of the details of what happens. So it is opening a new door that other people will follow." 

A black hole is created when a huge star runs out of fuel for nuclear fusion and collapses under its own gravity. The star's outer layers are expelled, and its core falls in on itself, with the pull of gravity becoming ever stronger, until what's left is the core's mass condensed into an extremely small area. According to general relativity, this area is a single point of space-time, and the density there is infinitely large -- a singularity.

But most scientists think singularities don't really exist, that they're just a sign that equations have broken down and fail to adequately describe reality. Loop quantum gravity appears to be an improvement on general relativity in describing black holes because it doesn't produce a singularity.

The idea is based on the notion of "quantization," which breaks an entity up into discrete pieces.Whilequantum mechanics says atoms exist in quantized, discrete states, loop quantum gravity posits that space-time itself is made of quantized, discrete bits, in the form of tiny, one-dimensional loops.

"The loop means the fundamental excitations of space-time themselves are one-dimensional in nature," said Jorge Pullin, a physicist at Louisiana State University, who co-authored the new study with Rodolfo Gambini of the University of the Republic in Montevideo, Uruguay. "The fundamental building block is a loop, or network of loops. For a visual image, think of a mesh fabric."

This way of portraying space-time changes fundamental physics, especially in extreme settingssuch as black holes or the Big Bang -- which is thought to have birthed the universe. The Big Bang, like black holes, is indescribable under general relativity, understood only as a singularity.

"The subject really took off in 2005 when it was realized loop quantum gravity can naturally resolve the Big Bang singularity and that quantum space-time is much larger than what Einstein envisioned," Ashtekar told SPACE.com.

Pullin and Gambini said their work is just a preliminary step, far from a full description of the true complexity of black holes.

"This model we've done is extremely simple," Pullin said. Under their simplified model,"the black hole exists forever and doesn't evolve. As a consequence I cannot tell you exactly what nature is going to do inside a black hole. It could be that the singularity gets replaced by a region that gets highly curved, but not infinitely curved. Or it could be that it just doesn't make sense -- you get a region which doesn't behave like classical space-time. It would interact with particles in different ways than we normally think."

Now that they've achieved this step, the researchers hope to advance their work by making the black holes in their model more dynamic and changeable.

"The black holes we studied were in empty space -- there was no matter in them. They were pure space-time," Pullin said."We're trying to add matter, because then it addsdynamics. We're in the middle of that now."

Top 10 Strangest Things In Space

Top 10 Strangest Things In Space

Let’s be honest: space is an absolutely crazy place. Most science fiction writers throw in a planet with two stars that looks vaguely like Southern California, and call it a day. But the cosmos is a lot stranger than we give it credit for:

10

Hypervelocity Stars

Everyone knows that shooting stars are just meteors entering the atmosphere, right? If you didn’t, congratulations—you just failed the fourth grade. What some people don’t know, however, is that real shooting stars exist as well; they’re called hypervelocity stars. These are big, fiery balls of gas rocketing through space at millions of miles per hour.

When a binary star system is gobbled down by the supermassive black hole (that’s the scientific term, by the way) at the center of a galaxy, one of the two partners is consumed, while the other is ejected at high speed. Just try to imagine a huge ball of gas, four times the size of our sun, hurtling out from our galaxy at millions of miles per hour.

9

The Planet From Hell

Gliese 581 c wants to kill you. Seriously. Scientists have determined that this hell of a planet is the most likely candidate for future colonization, despite the fact the entire planet’s out to get you.

This planet orbits a red dwarf star, many times smaller than our Sun, with a luminosity of only 1.3% of our sun. This means that the planet is far closer to its star than we are to ours. Because of this, it is stuck in a state of tidal locking, meaning that one side of the planet is always facing the star, and one side is always facing away—just like our moon’s relationship with Earth.

The tidal locking of the planet alone results in some pretty odd features. Stepping out onto the star-side of the planet would immediately melt your face off, whereas standing on the opposite side of the planet, where there is no sun, would freeze you instantly. However, in between these two extremes is a small belt where life could theoretically exist.

Living on Gliese 581 c would have its challenges, though. The star it orbits is a Red Dwarf, which means that it is at the lower frequency end of our visible spectrum, bathing the entire sky of Gliese 581 c in a hellish red color. Another side effect of this is the fact that photosynthesizing plants would have to adapt to the constant bombardment of infrared radiation, rendering them a deep black color. That Greek salad wouldn’t seem so appetizing any more…

8

The Castor System

As if one or two giant, fiery balls of gas weren’t enough, here we have theCastor System. As one of the two bright stars from the Gemini constellation in our night sky, it has some serious luminosity. This is because the Castor System isn’t one, or two, but six stars, all orbiting around a common central mass.

Three binary star systems orbit each other here, with two hot and bright A-Type stars being stuck in the system, as well as four M-type red dwarves. All together, though, these six stars put out roughly 52.4 times more luminositythan that of our sun.

7

Space Raspberries and Rum

For the last few years, scientists have been studying a dust cloud near the center of our Milky Way galaxy. If there’s a God out there, it seems that he decided to get creative—this dust cloud, named Sagittarius B2, smells of rum and tastes like raspberries.

The gas cloud in question consists largely of ethyl formate, which is known to give raspberries their taste, and rum its distinctive smell. This large cloud is said to contain a billion, billion, billion liters of the stuff—which would be great, if it wasn’t rendered undrinkable by pesky particles like propyl cyanide.

The creation and distribution of these more complex molecules is still a mystery to scientists, however, so we won’t be opening up an intergalactic pub anytime soon.

6

A Planet of Burning Ice

Do you remember Gliese? That hell-hole of a star that we visited earlier? We’re heading back to the same solar system for this one. As if one murderous planet wasn’t enough, Gliese supports a planet made almost entirely out of ice—at 439 degrees Celsius.

Gliese 436 b is, quite simply, a burning ice cube. Imagine Hoth from Star Wars—except that it’s on fire. The only reason this ice stays solid is because of the huge amount of water present on the planet; the gravity pulls it all in towards the core, keeping the water molecules so densely packed that they cannot evaporate.

5

The Diamond Planet

Finally: a planet fit for Oprah, or perhaps even Bill Gates. 55 Cancri e—madeentirely out of crystallized diamond—would be priced at 26.9 nonillion dollars. That’s the kind of stuff that even the Sultan of Brunei dreams about at night.

The huge diamond planet was once a star in a binary system, until its partner began to cannibalize it. However, the star was not able to pull its carbon core away, and carbon is just a ton of heat and pressure away from being a diamond—so at a surface temperature of 1648 degrees Celsius, the conditions are almost perfect.

One third of the mass of the planet is said to be pure diamond, and whereas Earth is covered in water and abundant in oxygen, this planet is made mainly of graphite, diamond, and a few other silicates.

The huge gemstone is two times the size of Earth, and has eight times the mass, making it a “Super-Earth.”

4

The Himiko Cloud

If there has ever been any object that has shown us the origins of a primordial galaxy, this is it. The Himiko Cloud is the most massive object ever found in the early universe, and it dates to only 800 million years after the Big Bang. The Himiko Cloud astounds scientists with its sheer size, roughly half that of our Milky Way Galaxy.

Himiko belongs to what is known as the “reionization epoch,” or the period from around 200 million to one billion years after the Big Bang—and it’s the first glimpse scientists have managed to get of the early formation of galaxies. To make it even cooler, it has been introduced as the “Giant Mystery Blob Discovered Near the Dawn of Time” by Space.com.

3

The Universe’s Largest Water Reservoir

Twelve billion light years away, the universe’s largest water reservoir resides in the heart of a quasar. Containing 140 trillion times the amount of water in Earth’s oceans, and found near the colossal black hole at the center of the quasar, the water unfortunately manifests itself in the form of a massive cloud of gas, several hundred light years in diameter—our dreams of the universe’s most kick-ass water slide have been destroyed!

But the kicker is that this black hole, twenty billion times the size of our sun, is constantly spewing out huge amounts of energy—equivalent to what would be produced by 1000 trillion suns.

2

The Universe’s Largest Electrical Current

Only a few years ago, scientists stumbled upon an electrical current of cosmic proportions: 10^18 amps, or roughly one trillion lightning bolts. With that kind of power, you could even use that pesky seven-blade electric razor you have lying around!

The lightning is thought to originate from an enormous black hole in the center of the galaxy, which has a core that is supposedly a “huge cosmic jet.” Apparently, the black hole’s huge magnetic field allows it to fire up this lightning bolt through gas and dust to a distance of over one hundred and fifty thousand light years away. And we thought that our galaxy was big—this single lightning bolt is one and a half times the size of it.

1

The LQG

So yeah, the Himiko Cloud is pretty big—like, half the size of our galaxy. Big whoop, right? Well, what about a structure in space so enormous that it breaks the conventional laws for modern astronomy? This structure, my friends, is the LQG—the Large Quasar Group.

Our galaxy, the Milky Way, is only one hundred thousand light years across. Think about that for a moment; if something happens on the far side of the galaxy, it would take a hundred thousand years for the light to reach the opposite end. That means that when we watch an event take place at the other end of our galaxy, it actually occurred when the human species was just beginning to form.

Now, take that length of time, and multiply it by forty thousand. That’s right—the Large Quasar Group is four billion light years across. The cluster of seventy-four quasars actually breaks the rules of standard astrophysics, since the maximum size of any cosmic structure should be only 1.2 billion light years across.

Scientists have absolutely no idea how this huge structure formed, since they had previously only been aware of other clusters of perhaps several hundred million light years across. The gargantuan structure absolutely spits on a certain physical law, which states that when viewed from a distance, the universe would look relatively uniform. This is exactly the type of condescending cosmic structure that looks over at our galaxy and, with a smirk, says “cute.”

Warp Drive & Transporters: How 'Star Trek' Technology Works (Infographic)

The original "Star Trek" television series featured technology that had first appeared decades earlier in science fiction stories. Pulp heroes had been wielding ray guns, flying faster than light and teleporting from place to place since the 1930s. But perhaps the true inspiration of Star Trek’s superscience is the revolutionary physics discoveries of the early 20th century. Relativity, discovered by Albert Einstein and quantum physics, pioneered by Max Planck  revealed a universe far different than ordinary human experience might suggest.

Although Einstein’s theory forbids matter to accelerate past the speed of light, the demands of sci-fi storytelling require that people be able to travel between the stars in a reasonable amount of time, usually hours, or at most, days. Enter the space warp drive, or as it was called in "Star Trek’s" pilot episode, "hyperdrive."

Warp drive in Star Trek works by annihilating matter (in the form of deuterium, a kind of hydrogen gas) and antimatter in a fusion reaction mediated by dilithium crystals. This produces the enormous power required to warp space-time and drive the ship faster than light.

The Evolution of 'Star Trek' (Infographic)

The crew of the Enterprise measures velocity in warp factors. Warp factor 8 equals the cube of 8 (8 times 8 times 8), or 512 times light speed.

Even this velocity is too slow to allow starships to travel as quickly as they appear to on TV. In reality, the script writers arbitrarily allowed the Enterprise to get to wherever it was going, as fast as was convenient for storytelling. By the era of "Star Trek: The Next Generation," the warp speed scale was recalibrated. Under the new scale, a starship could get from Earth to Alpha Centauri in about 37 hours at warp factor 8.

USS Enterprise Evolution in Photos (Gallery)

Science fiction author E.E. "Doc" Smith describes a spaceship traveling at a speed "thousands of times greater than that of light" in his novel "Skylark of Space," written between 1915 and 1921 and serialized in "Amazing Stories" magazine in 1928.

The technology and style of "Star Trek" was influenced by the 1955 film "Forbidden Planet." United Planets Cruiser C-57D (above) used its quanto-gravitic hyperdrive to greatly surpass the speed of light. The cruiser travels to the star Altair, 16.7 light-years from Earth, in 378 days.

In 1994, Miguel Alcubierre proposed moving not a spaceship, but space itself, faster than light. All that would be required is to distort the fabric of space-time into a bubble surrounding a spaceship. Enormous energy would be required, but once created, the bubble would move independently of the rest of the universe, even faster than light.

The bubble moves by compressing the space-time in front of it and expanding the space-time behind it.

The Top 10 Star Trek Technologies

NASA scientist Harold "Sunny" White believes as-yet-undiscovered "negative energy" could be used to create the space-warp bubble, using a smaller amount of total energy than Alcubierre thought possible.

A plausible alternative to traveling across space is the wormhole, a shortcut between two widely separated points in space-time. Scientists Albert Einstein and Nathan Rosen first proposed the wormhole, or "Einstein-Rosen Bridge," in 1935. Wormholes have not yet been observed in nature, but they are not forbidden by our current understanding of physics.

If they exist, wormholes would permit travel faster than light and backward through time (at least to the time when the wormhole was created).

In "Star Trek's" Transporter device, normal matter is converted temporarily into energy, then beamed to a target point for restoration to its original pattern and structure. The Transporter has a range of about 16,000 miles (25,750 kilometers).

The "Vibra-Transmitter" described in Frank K. Kelley’s 1933 story "Into the Meteorite Orbit" functions similarly to Star Trek’s Transporter. The human body is "reduced to vibration traveling on a wave-channel" and then reintegrated into matter in a receiving chamber.

In real-world science, subatomic particles can be quantum teleported, but this only transmits a quantum state between a pair of entangled particles, not the particles themselves. The human body contains an immense number of atoms, about 10^27 (one followed by 27 zeroes). Recording the quantum states of all these atoms would require an unrealistic amount of data storage. Even worse, quantum physics prevents the precise measurement of the individual atoms.

Deflector shields (or "screens") are an invisible force-field barrier activated automatically by the ship's computer when needed. Screens can be maintained continually for 20 hours before the ship’s power is exhausted. Transporters cannot be used when the screens are enveloping the ship.

Navigational deflector beams sweep the space ahead of the ship to shove aside obstacles such as small asteroids. Anything too large to be deflected triggers the ship’s computer to change course to avoid collision.

In earlier sci-fi, deflectors for diverting meteoroids out of a spaceship’s path show up in "The Ethical Equations” by Murray Leinster, published in "Astounding Science Fiction" in 1945. 

Lawrence Krauss, in his book "The Physics of Star Trek," supposes that to bend light (or phaser beams), deflector shields would have to warp space-time around the starship. But if warp drive is possible, deflector shields that work this way are perhaps also possible.

Tractor beams are a form of reverse deflector beam, pulling instead of pushing. The tractor beam has a range of about 100,000 miles (160,930 km).

E.E. "Doc" Smith uses the exact term "tractor beam" to describe force beams for grabbing objects in space in his 1931 story "Spacehounds of IPC," published in "Amazing Stories."

In real-world science, microscopic particles of matter have been manipulated in the laboratory with laser beams. Starships are much more massive. Tractor beams that work on an electromagnetic principle might be plausible in theory. However, Newton’s laws require that if the Enterprise pulls on another object with its tractor beam, the Enterprise itself will be moved toward the object. The Enterprise must fire thrusters to remain in place during the operation.

A phaser is an energy beam that can be "phased" to interfere with the wave pattern of any material object. Settings include dematerialize (converts matter to energy), disrupt (breaks down molecular cohesion), heat (increases molecular velocity) and stun (impacts the nervous system of a living target). Phasers can also be adjusted for use as cutting torch or welder.  A phaser set to overload creates a powerful explosion. The ship's main phaser batteries can destroy matter over vast distances and are powered directly by the warp engines. 

The Martian heat ray in H.G. Wells’ 1898 novel "The War of the Worlds" is very much like a ray gun or death beam. In the 1920s and 1930s, some scientists, including Nikola Tesla, believed that a death ray capable of killing at a distance was feasible. Toy Buck Rogers guns began appearing in the 1930s, one of which was called a “disintegrator pistol.”

Weapons exist today that are capable of stunning the human nervous system (the taser, for example). However, tasers require physical contact to deliver their charge. Due to the inverse square law by which energy decreases as distance increases, to disintegrate matter at a distance a phaser weapon would have to generate an incredible amount of energy. Military research continues into developing directed energy weapons capable of shooting down missiles.

A photon torpedo is an energy pod of matter and antimatter separated by a magno-photon force field. They can be fired directly as torpedoes, laid in a mine field or scattered in an enemy’s path like modern-day depth charges. Electrochemical, proximity and other fuses are available. 

Photon torpedoes require a quantity of antimatter. Generating even a few atoms of antimatter uses up an enormous amount of energy. The starship’s warp drive, powered by antimatter, also has this problem.

In theory, the explosive yield of one gram (0.04 ounces) of antimatter and an equal quantity of matter is about 43 kilotons (possibly lower in actual practice). Background material for the Next Generation series says that photon torpedoes carry 1.5 kilograms 3.3 pounds) of antimatter. 

Things you don't know about the Milky Way Galaxy

Things you don't know about the Milky Way Galaxy 

So you’ve lived here all your life — in fact, everyone has — but what do you really know about the Milky Way galaxy? Sure, you know it’s a spiral, and it’s 100,000 light years across. And of course, BABloggees are smarter, more well-read, and better looking than the average population, but be honest: do you know all ten of these things? Really?

Liar.

So let’s see if these really are Ten Things You Don’t Know About the Milky Way Galaxy.

1) It’s a barred spiral.

You might know that the Milky Way is a spiral galaxy, perhaps the most beautiful galaxy type. You’ve seen ‘em: majestic arms sweeping out from a central hub or bulge of glowing stars. That’s us. But a lot of spirals have a weird feature: a rectangular block of stars at the center instead of a sphere, and the arms radiate away from the ends of the block. Astronomers call this block a bar, and, you guessed it: we have one.

Is fact, ours is pretty big. At 27,000 light years end-to-end, it’s beefier than most bars. Of course, space is a rough neighborhood. Who wouldn’t want a huge bar located right downtown?

2) There’s a supermassive black hole at its heart.

At the very center of the Galaxy, right at its very core, lies a monster: a supermassive black hole.

We know it’s there due to the effect of its gravity. Stars very near the center — some only a few dozen billion kilometers out — orbit the center at fantastic speeds. They scream around their orbits at thousands of kilometers per second, and their phenomenal speed betrays the mass of the object to which they’re enthralled. Applying some fairly basic math, it’s possible to determine that the mass needed to accelerate the stars to those speeds must tip the cosmic scales at four million times the mass of the Sun! Yet in the images, nothing can be seen. So what can be as massive as 4,000,000 Suns and yet not emit any light?

Right. A black hole.

Even though it’s huge, bear in mind that the Galaxy itself is something like 200 billion solar masses strong, so in reality the black hole at the center is only a tiny fraction of the total mass of the Galaxy. And we’re in no danger of plunging into it: after all, it’s 250,000,000,000,000,000 kilometers away.

It’s thought now that a supermassive black hole in the center of a galaxy forms along with the galaxy itself, and in facts winds blown outward as material falls in affects the formation of stars in the galaxy. So black holes may be dangerous, but it’s entirely possible the Sun’s eventual birth — and the Earth’s along with it — may have been lent a hand by the four million solar mass killer so far away.

3) It’s a cannibal.

Galaxies are big, and have lots of mass. If another, smaller galaxy passes too close by, the bigger galaxy can rip it to shreds and ingest its stars and gas. 

The Milky Way is pretty, but it’s savage, too. It’s currently eating several other galaxies. They’ve been ripped into long, curving arcs of stars that orbit the center of the Milky Way. Eventually they’ll merge completely with us, and we’ll be a slightly larger galaxy. Ironically though, the galaxies add their mass to ours, making it more likely we’ll feed again. Eating only makes galaxies hungrier.

4) We live in a nice neighborhood…

The Milky Way is not alone in space. We’re part of a small group of nearby galaxies called — get ready to be shocked — the Local Group. We’re the heaviest guy on the block, and the Andromeda galaxy is maybe a bit less massive, though it’s actually spread out more. The Triangulum galaxy is also a spiral, but not terribly big, and there are other assorted galaxies dotted here and there in the Group. All together, there are something like three dozen galaxies in the Local Group, with most being dinky dwarf galaxies that are incredibly faint and difficult to detect.

5) … and we’re in the suburbs.

The Local Group is small and cozy, and everyone makes sure their lawns are mowed and houses painted nicely. That’s because if you take the long view, we live in the suburbs. The big city in this picture is the Virgo Cluster, a huge collection of about 2000 galaxies, many of which are as large or larger than the Milky Way. It’s the nearest big cluster; the center of it is about 60 million light years away. We appear to be gravitationally bound to it; in other words, we’re a part of it, just far-flung. The total mass of the cluster may be as high as a quadrillion times the mass of the Sun.

6) You can only see 0.000003% percent of it.

When you got out on a dark night, you can see thousands of stars. But the Milky Way has two hundred billion stars in it. You’re only seeing a tiny tiny fraction of the number of stars tooling around the galaxy. In fact, with only a handful of exceptions, the most distant stars you can readily see are 1000 light years away. Worse, most stars are so faint that they are invisible much closer than that; the Sun is too dim to see from farther than about 60 light years away… and the Sun is pretty bright compared to most stars. So the little bubble of stars we can see around us is just a drop in the ocean of the Milky Way.

7) 90% of it is invisible.

When you look at the motions of the stars in our galaxy, you can apply some math and physics and determine how much mass the galaxy has (more mass means more gravity, which means stars will move faster under its influence). You can also count up the number of stars in the galaxy and figure out how much mass they have. Problem is, the two numbers don’t match: stars (and other visible things like gas and dust) make up only 10% of the mass of the galaxy. Where’s the other 90%?

Whatever it is, it has mass, but doesn’t glow. So we call it Dark Matter, for lack of a better term (and it’s actually pretty accurate). We know it’s not black holes, dead stars, ejected planets, cold gas — those have all been searched for, and marked off the list — and the candidates that remain get pretty weird (like WIMPs). But we know it’s real, and we know it’s out there. We just don’t know what it is. Smart people are trying to figure that out, and given the findings in recent years, I bet we’re less than a decade from their success.

8) Spiral arms are an illusion.

Well, they’re not an illusion per se, but the number of stars in the spiral arms of our galaxy isn’t really very different than the number between the arms!The arms are like cosmic traffic jams, regions where the local density is enhanced. Like a traffic jam on a highway, cars enter and leave the jam, but the jam itself stays. The arms have stars entering and leaving, but the arms themselves persist (that’s why they don’t wind up like twine on a spindle).

Just like on highways, too, there are fender benders. Giant gas clouds can collide in the arms, which makes them collapse and form stars. The vast majority of these stars are faint, low mass, and very long-lived, so they eventually wander out of the arms. But some rare stars are very massive, hot, and bright, and they illuminate the surrounding gas. These stars don’t live very long, and they die (bang!) before they can move out of the arms. Since the gas clouds in the arms light up this way, it makes the spiral arms more obvious.

We see the arms because the light is better there, not because that’s where all the stars are.

9) It’s seriously warped.

The Milky Way is a flat disk roughly 100,000 light years across and a few thousand light years thick (depending on how you measure it). It has the same proportion as a stack of four DVDs, if that helps.

Have you ever left a DVD out in the Sun? It can warp as it heats up, getting twisted (old vinyl LPs used to be very prone to this). The Milky Way has a similar warp!

The disk is bent, warped, probably due to the gravitational influence of a pair of orbiting satellite galaxies. One side of the disk is bent up, if you will, and the other down. In a sense, it’s like a ripple in the plane of the Milky Way. It’s not hard to spot in other galaxies; grab an image of the Andromeda galaxy and take a look. At first it’s hard to see, but if you cover the inner part you’ll suddenly notice the disk is flared up on the left and down on the right. Andromeda has satellite galaxies too, and they warp its disk just like our satellite galaxies warp ours.

As far as I can tell, the warp doesn’t really affect us at all. It’s just a cool thing you may not know about the Milky Way. Hey, that would make a good blog entry!

10) We’re going to get to know the Andromeda galaxy a lot better.

Speaking of Andromeda, have you ever seen it in the sky? It’s visible to the naked eye on a clear, dark, moonless night (check your local listings). It’s faint, but big; it’s four or more degrees across, eight times the apparent size of the Moon on the sky.

If that doesn’t seem too big, then give it, oh, say, two billion years. Then you’ll have a much better view.

The Andromeda Galaxy and the Milky Way are approaching each other, two cosmic steam engines chugging down the tracks at each other at 200 kilometers per second. Remember when I said big galaxies eat small ones? Well, when two big galaxies smack into each other, you get real fireworks. Stars don’t physically collide; they’re way too small on this scale. But gas clouds can, and like I said before, when they do they form stars. So you get a burst of star formation, lighting up the two galaxies.

In the meantime, the mutual gravity of the two galaxies draw out long tendrils from the other, making weird, delicate arcs and filaments of stars and gas. It’s beautiful, really, but it indicates violence on an epic scale.