Tag: physics

Astronomers Might Have Finally Detected Where Mysterious, Extra-Galactic Neutrinos Are Coming From

Just over three years ago, physicists working in Antarctica announced they’d detected the first evidence of mysterious subatomic particles, known as neutrinos, coming from outside our galaxy.

It was a huge moment for astrophysics, but since then, no one’s quite been able to figure out where those particles are coming from, and what’s sending them hurtling our way.

Until now, that is – a team of astronomers has just identified the possible source of one these extragalactic visitors, and it appears that it started its journey to us nearly 10 billion years ago, when a massive explosion erupted in a galaxy far, far away.

Let’s step back for a second here though and explain why this is a big deal. Neutrinos are arguably the weirdest of the fundamental subatomic particles.

They don’t have any mass, they’re incredibly fast, and they’re pretty much invisible, because they hardly ever interact with matter.




Like tiny ghosts, billions of neutrinos per second are constantly flowing through us, and we never even know about it.

In order to detect them, researchers have step up extravagant labs, like the IceCube Neutrino Observatory at the South Pole, where they wait patiently to capture glimpses of neutrinos streaking through the planet, and measure how energetic they are, to try to work out where they came from.

Usually that source is radioactive decay here on Earth or inside the Sun, or maybe from the black hole at the centre of our galaxy.

But in 2013, the IceCube researchers announced they’d detected a couple of neutrinos so unimaginably energetic, they knew they must have come from outside our galaxy.

These neutrinos were named ‘Bert’ and ‘Ernie‘ (seriously) and they were the first evidence of extragalactic neutrinos.

Their discovery was followed by the detection of a couple of dozen more, slightly less energetic, extragalactic neutrinos over the coming months.

Then at the end of 2012, they spotted ‘Big Bird‘.

At the time it was the most energetic neutrino ever detected, with energy exceeding 2 quadrillion electron volts – that’s more than a million million times greater than the energy of a dental X-ray.

Not bad for a massless ghost particle.

Since then, teams across the world have been working to figure out where the hell this anomaly had come from. And now we might finally have a suspect.

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Pass it on: Popular Science

The Mystery Of How Easter Island Statues Got Their Colossal Hats Might Finally Be Solved

It’s a towering problem, one to stump the most determined of milliners. You’ve carved almost 1,000 immense statues standing up to 10 metres (33 ft) tall. And now you want to put their hats on.

There’s just one problem. The hats, like the graven colossi themselves, are hewn out of solid rock, and weigh several tonnes a piece. How on Earth could you ever lift and fit this hulking headwear?

This ancient puzzle is just one of many posed by the strange stone legacy of Easter Island, whose unflinching moai statues maintain their silent vigil long centuries after the mysterious collapse of the Polynesian Rapa Nui society that erected them.

Of the many questions that surround the island’s past, two tend to stand out,” explains anthropologist Carl Lipo from Binghamton University.

How did people of the past move such massive statues, and how did they place such massive stone hats (pukao) on top of their heads?




Researchers already solved the first part of the puzzle. For decades, archaeologists have experimented with various methods of ‘walking’ the moai – rocking replica statues from side to side along prepared paths, ever slowly inching the towering figures forward.

It’s kind of like shuffling a fridge into a new kitchen (although decidedly more epic).

But what about the world’s heaviest hats?

In a new study, Lipo and his team suggest that the cylindrical pukao – with diameters up to 2 metres (6.5 feet) and weighing 12 tonnes – may have been rolled across the island from the red scoria quarries they were cut from.

A diagram of how the pukao might have been placed.

That’s how they were transported to the moai, but to lift them onto the statues’ elevated heads, props – and a little physics trickery – would be needed, with a ramp-and-ropes technique called parbuckling.

The solution may seem simple in hindsight, but to show that the hypothetical rig would have been workable for Rapa Nui islanders required building detailed 3D models of 50 pukao and 13 red scoria cylinders found on the island, and calculating how the huge hats may have been pulled up the inclined ahu platforms.

“Transport equations based on Newtonian physics, human strength estimates, and estimates of moai height and pukao mass at four different ahu verify that pukao transport by rolling up a ramp is physically feasible with 15 or fewer people,” the researchers write, “even in the case of the most massive pukao (about 12 metric tonnes).”

This technique means it wouldn’t have required huge number of peoples or resources to construct and assemble the moai and pukao, which helps discredit the view that the Rapa Nui may somehow have helped destroy their own civilisation through overpopulation taxing the island’s natural resources.

And yet, for all that ingenuity and coordinated effort, most of the pukao are sadly no longer affixed to the moai heads.

Centuries of weather, erosion, and animal activity have seen the majority of these rock hats fall back to Earth, where they rest crumbled and damaged around the island surface – which is one of the reasons you rarely see this monumental headwear in photos of the iconic statues.

Something to think about next time your hat blows off on a windy day.

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Pass it on: Popular Science

Do Black Holes Die?

There are some things in the universe that you simply can’t escape. Death. Taxes. Black holes. If you time it right, you can even experience all three at once.

Black holes are made out to be uncompromising monsters, roaming the galaxies, voraciously consuming anything in their path.

And their name is rightly deserved: once you fall in, once you cross the terminator line of the event horizon, you don’t come out. Not even light can escape their clutches.

But in movies, the scary monster has a weakness, and if black holes are the galactic monsters, then surely they have a vulnerability. Right?

In the 1970s, theoretical physicist Stephen Hawking made a remarkable discovery buried under the complex mathematical intersection of gravity and quantum mechanics: Black holes glow, ever so slightly, and, given enough time, they eventually dissolve.




Wow! Fantastic news! The monster can be slain! But how? How does this so-called Hawking Radiation work?

Well, general relativity is a super-complicated mathematical theory. Quantum mechanics is just as complicated.

It’s a little unsatisfying to respond to “How?” with “A bunch of math,” so here’s the standard explanation: the vacuum of space is filled with virtual particles, little effervescent pairs of particles that pop into and out of existence, stealing some energy from the vacuum to exist for the briefest of moments, only to collide with each other and return to nothingness.

Every once in a while, a pair of these particles pops into existence near an event horizon, with one partner falling in and the other free to escape.

Unable to collide and evaporate, the escapee goes on its merry way as a normal non-virtual particle.

Here’s the thing: I don’t find that answer especially satisfying, either.

For one, it has absolutely nothing to do with Hawking’s original 1974 paper, and for another, it’s just a bunch of jargon words that fill up a couple of paragraphs but don’t really go a long way to explaining this behavior.

It’s not necessarily wrong, just…incomplete.

One way or the other, as far as we can tell, black holes do dissolve. I emphasize the “as far as we can tell” bit because, like I said at the beginning, generality is all sorts of hard, and quantum field theory is a beast.

Put the two together and there’s bound to be some mathematical misunderstanding.

But with that caveat, we can still look at the numbers, and those numbers tell us we don’t have to worry about black holes dying anytime soon.

A black hole with the mass of the sun will last a wizened 10^67 years. Considering that the current age of our universe is a paltry 13.8 times 10^9 years, that’s a good amount of time.

But if you happened to turn the Eiffel Tower into a black hole, it would evaporate in only about a day. I don’t know why you would, but there you go.

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Pass it on: Popular Science

Elon Musk Says We’re Probably Characters In Some Advanced Civilization’s Video Game

I don’t want to freak you out here, but there’s a chance you’re not the only ‘you’ in existence.

I’m not talking about the possibility that you might actually have two different brains, which means it’s virtually impossible to tell which one is ‘you’.

I’m talking about the fact that there could well be countless parallel universes, and each one contains a slightly different version of you.

Within that parallel universe construct, our own reality might not be as ‘real’ as you think. Are some of the most massive objects in our Universe nothing but holograms?

Is our Universe itself a hologram? Is this whole thing one giant simulation and we’re just characters in the most advanced video game ever? I swear I’m not high.




Everything I just mentioned is part of actual thought experiments that have been devised and debated over by the world’s best thinkers for years now, because one way or another, we have to make sense of this very strange and incredibly unlikely reality we’ve found ourselves in.

At Recode’s annual Code Conference this week in California, billionaire tech genius Elon Musk was asked about the possibility of us humans being unwitting participants in a giant simulation built by some alien civilization that’s far more advanced than our own.

His argument is pretty simple, if we look at our own history of video games. Forty years ago, video games meant stuff like Pong and Space Invaders.

Now we have photorealistic, three-dimensional stuff that looks like this, and we could have millions, potentially even billions, of people all playing the same game online at the same time.

Sure, there’s a certain ‘uncanny valley‘ quality to our video game counterparts right now, but think of what things are going to look like in another 40, or even 20 years’ time, with virtual and augmented reality already trying to inch its way into our living rooms.

Musk explains:

“If you assume any rate of improvement at all, then the games will become indistinguishable from reality, even if that rate of advancement drops by a thousand from what it is now. Then you just say, okay, let’s imagine it’s 10,000 years in the future, which is nothing on the evolutionary scale.

So given that we’re clearly on a trajectory to have games that are indistinguishable from reality, and those games could be played on any set-top box or on a PC or whatever, and there would probably be billions of such computers or set-top boxes, it would seem to follow that the odds that we’re in base reality is one in billions.”

It might not be the most comforting thing in the world to think about – our reality isn’t at all what we think it is – but Musk says all of this being one big video game is about the best option we could hope for, given the alternatives.

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Pass it on: Popular Science

What Came Before The Big Bang?

It is difficult enough to imagine a time, roughly 13.7 billion years ago, when the entire universe existed as a singularity.

According to the big bang theory, one of the main contenders vying to explain how the universe came to be, all the matter in the cosmos – all of space itself – existed in a form smaller than a subatomic particle.

Once you think about that, an even more difficult question arises: What existed just before the big bang occurred?

The question itself predates modern cosmology by at least 1,600 years. Fourth-century theologian St. Augustine wrestled with the nature of God before the creation of the universe.




His answer? Time was part of God’s creation, and there simply was no “before” that a deity could call home.

Armed with the best physics of the 20th century, Albert Einstein came to very similar conclusions with his theory of relativity.

Just consider the effect of mass on time. A planet’s hefty mass warps time — making time run a tiny bit slower for a human on Earth’s surface than a satellite in orbit.

The difference is too small to notice, but time even runs more slowly for someone standing next to a large boulder than it does for a person standing alone in a field.

The pre-big bang singularity possessed all the mass in the universe, effectively bringing time to a standstill.

Following this line of logic, the title of this article is fundamentally flawed.

According to Einstein’s theory of relativity, time only came into being as that primordial singularity expanded toward its current size and shape.

Case closed? Far from it. This is one cosmological quandary that won’t stay dead.

In the decades following Einstein’s death, the advent of quantum physics and a host of new theories resurrected questions about the pre-big bang universe. Keep reading to learn about some of them.

Here’s a thought: What if our universe is but the offspring of another, older universe? Some astrophysicists speculate that this story is written in the relic radiation left over from the big bang: the cosmic microwave background (CMB).

Astronomers first observed the CMB in 1965, and it quickly created problems for the big bang theory — problems that were subsequently addressed (for a while) in 1981 with the inflation theory.

This theory entails an extremely rapid expansion of the universe in the first few moments of its existence.

It also accounts for temperature and density fluctuations in the CMB, but dictates that those fluctuations should be uniform.

In chaotic inflation theory, this concept goes even deeper: an endless progression of inflationary bubbles, each becoming a universe, and each of these birthing even more inflationary bubbles in an immeasurable multiverse.

Other scientists place the formation of the singularity inside a cycle called the big bounce in which our expanding universe will eventually collapse back in on itself in an event called the big crunch.

A singularity once more, the universe will then expand in another big bang.

This process would be eternal and, as such, every big bang and big crunch the universe ever experiences would be nothing but a rebirth into another phase of existence.

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Pass it on: Popular Science

How Physics Can Help You Achieve The Perfect Egg Crack

cracked egg

What’s the best way to crack an egg?

Physicists explain that we’re predisposed to hit the egg against a hard surface where the egg is flattest, or, its center, where its oblong shape widens; that’s the point at which an egg is weakest.




The egg puts up more of a fight at its round, arched ends. This curvature creates an even distribution of pressure, which may explain why it’s all but impossible to crack an egg when it’s held lengthwise between your fingers.

To game this correctly, then, you should create an initial crack in the center of your egg that opens a cavity small enough to fit your thumb through.

egg

What comes next requires quick, careful precision: You expand this ripple ever so slightly with your hands so that the egg’s yolk tumbles out. Go too fast and the shell will collapse in your hands.

So, there you go. Now you’ve got some new vocabulary, borrowed from the wild world of fracture mechanics, to apply to a deceptively simple cooking act. If this registers as completely useless information, consider that egg-cracking is a difficult art to master for the less dexterous among us.

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The Physics Of Hitting A Baseball

Hitting the “sweet spot” is something that baseball players strive for. This is the location of the bat that is generally regarded as the best spot for hitting the ball.

It minimizes vibration of the bat and results in the maximum energy delivered to the ball, meaning it travels the farthest.

The “sweet spot” is a special point on the bat which minimizes stinging of the hands when the ball strikes there. Baseball players say that hitting the ball in this location “feels” the best, and results in the most solid hit.

If the baseball strikes outside of the sweet spot a painful stinging sensation is felt in the hands, due to bat vibration. In addition, this undesirable vibration reduces the energy that is delivered to the ball, so it doesn’t travel as far.




Here we are using physics to confirm what baseball players already know from experience.

It’s not easy to hit the sweet spot. For best results, contact with the ball must be made within 1/8″ of this special point. It is the main “good hit” criterion of players.

But it is one of the biggest challenges in Major League sports, where a round ball traveling at 90 mph has to hit a round bat swinging at 80 mph, at precisely this location.

The result is the ball flying off the bat at 110 mph, enough for a home run.

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Astrophysicists Spotted A ‘Galaxy Without Dark Matter’

An unusual galaxy far, far away is stumping astronomers not because of what’s there, but because of what’s missing.

About 65 million light-years away, the galaxy called NGC1052-DF2 is dim and diffuse, coming in at about one two-hundredths the mass of our Milky Way.

Normally, not all of a galaxy’s mass is visible. In addition to a mix of ordinary matter—like stars and planets and manatees—galaxies are expected to contain dark matter, an invisible substance that makes up most of the mass in the universe.

Although we can’t directly observe it, we know dark matter is there because we can see how its gravity affects ordinary matter.

Based on the ratio in other galaxies, an isolated galaxy like NGC1052-DF2 should have about a hundred times more dark matter than ordinary matter. But this one appears to have … almost none, scientists report today in Nature.




How did scientists figure that out?

Using a cluster of lenses called the Dragonfly Telephoto Array, a team led by Yale University’s Pieter van Dokkum took a really close look at NGC1052-DF2.

By tracking the motion of 10 embedded star clusters, the team could determine how much mass is tucked into the galaxy. And surprisingly, it’s about the same amount of mass they’d expect to see from the galaxy’s stars alone.

We really thought dark matter was not just an optional component of galaxies,” van Dokkum says, noting that the team has found several other similarly perplexing galaxies to scrutinize.

Why is this observation important?

One strange observation doesn’t necessarily break a theory. But finding a galaxy that’s more or less devoid of dark matter certainly suggests a few tantalizing things. First, it really challenges ideas about how galaxies form.

In modern galaxy formation theory, our understanding is that galaxies form in a dark matter halo,” says Stanford University’s Risa Wechsler.

There’s a pretty tight relationship between the amount of stars that formed and the dark matter there, at least when the galaxy formed.

In other words, no dark matter, no galaxy.

In theories proposing alternatives to dark matter, such as modifications to our understanding of gravity, whatever is mimicking the dark matter signature is not something that can be turned on or off—it should always be there.

So, van Dokkum says, “by not detecting the dark matter, we actually prove it’s real.”

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Pass it on: New Scientist

Astronomers Found Evidence For A ‘Dark’ Gravitational Force That Might Fix Einstein’s Most Famous Theory

Albert Einstein’s general theory of relativity predicts so much about the universe at large, including the existence of gravitational lenses or “Einstein rings.”

And yet his famous equations struggle to fully explain such objects.

While general relativity says a strong source of gravity — like the sun— will warp the fabric of space, bend light from a distant object, and magnify it to an observer, very big objects like galaxies and galaxy clusters make gravitational lenses that are theoretically too strong.




General relativity also can’t fully explain the spinning motions of galaxies and their stars.

That’s why most physicists think as much as 80% of the mass in the universe is dark matter: invisible mass that hangs out at the edges of galaxies.

Dark matter might be made of hard-to-detect particles, or perhaps an unfathomable number of tiny black holes. But we have yet to find smoking-gun evidence of either.

However, a contentious theory by Erik Verlinde at the University of Amsterdam suggests dark matter may not be matter at all.

What’s more, astronomers say his idea “is remarkable” in its ability to explain the behavior of more than 33,000 galaxies that they studied.

This does not mean we can completely exclude dark matter, because there are still many observations that Verlinde’s theory cannot yet explain,” study leader and physicist Margot Brouwer said in a YouTube video about the research.

However it is a very exciting and promising first step.”

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Pass it on: New Scientist

The Big Bang Wasn’t The Beginning, After All

A Universe that expands and cools today, like ours does, must have been hotter and denser in the past. Initially, the Big Bang was regarded as the singularity from which this ultimate, hot, dense state emerged. But we know better today.

The Universe began not with a whimper, but with a bang! At least, that’s what you’re commonly told: the Universe and everything in it came into existence at the moment of the Big Bang.

Space, time, and all the matter and energy within began from a singular point, and then expanded and cooled, giving rise over billions of years to the atoms, stars, galaxies, and clusters of galaxies spread out across the billions of light years that make up our observable Universe.

It’s a compelling, beautiful picture that explains so much of what we see, from the present large-scale structure of the Universe’s two trillion galaxies to the leftover glow of radiation permeating all of existence.

Unfortunately, it’s also wrong, and scientists have known this for almost 40 years.

The idea of the Big Bang first came about back in the 1920s and 1930s. When we looked out at distant galaxies, we discovered something peculiar: the farther away from us they were, the faster they appeared to be receding from us.




According to the predictions of Einstein’s General Relativity, a static Universe would be gravitationally unstable; everything needed to either be moving away from one another or collapsing towards one another if the fabric of space obeyed his laws.

The observation of this apparent recession taught us that the Universe was expanding today, and if things are getting farther apart as time goes on, it means they were closer together in the distant past.

An expanding Universe doesn’t just mean that things get farther apart as time goes on, it also means that the light existing in the Universe stretches in wavelength as we travel forward in time.

Since wavelength determines energy (shorter is more energetic), that means the Universe cools as we age, and hence things were hotter in the past.

It’s tempting, therefore, to keep extrapolating backwards in time, to when the Universe was even hotter, denser, and more compact.

First noted by Vesto Slipher, the more distant a galaxy is, on average, the faster it’s observed to recede away from us. For years, this defied explanation, until Hubble’s observations allowed us to put the pieces together: the Universe was expanding.

Theorists thinking about these problems started thinking of alternatives to a “singularity” to the Big Bang, and rather of what could recreate that hot, dense, expanding, cooling state while avoiding these problems.

The conclusion was inescapable: the hot Big Bang definitely happened, but doesn’t extend to go all the way back to an arbitrarily hot and dense state.

Instead, the very early Universe underwent a period of time where all of the energy that would go into the matter and radiation present today was instead bound up in the fabric of space itself.

That period, known as cosmic inflation, came to an end and gave rise to the hot Big Bang, but never created an arbitrarily hot, dense state, nor did it create a singularity.

What happened prior to inflation — or whether inflation was eternal to the past — is still an open question, but one thing is for certain: the Big Bang is not the beginning of the Universe!

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Pass it on: New Scientist