Big Bang Archives

November 17, 2014December 23, 2015 by Brian Koberlein

Where’s All The Antimatter?

Protons, neutrons, electrons - particles in an atom.

One of the biggest mysteries in the Universe is the fact there there’s matter, and not antimatter. Where did it all go?

When we look around, everything we can see is made of matter. For every type of matter from electrons, protons and quarks there is a similar type of matter known as antimatter. So why aren’t there piles of antimatter rocks, cars and chocolate bars just lying around? Why does Scotty always have a little extra kicking around in his liquor cabinet? And where do I get mine?

The primary difference between matter and antimatter is that they have opposite electric charge. Which seems pretty mundane. The negatively charged electron has an antiparticle known as the positron, which has a positive electric charge.

Anti-protons have a negative charge, and are just flat out grumpy. We’ve been able to create these particles in the lab, and have even been able to create small amounts of anti-hydrogen consisting of a positron bound to an antiproton, when examined closely there’s were shown to have a goatee and a little colorful sash or dagger.

When we create particles in accelerators such as the Large Hadron Collider, we seem to get equal amounts of matter and antimatter. This suggests that when particles were formed soon after the big bang, there should have been equal amounts of matter and antimatter.

Particle Collider — Large Hadron Collider (CERN/LHC/GridPP)

But the universe we observe is only made of matter, and… here’s the best part… we have no idea why. Why didn’t the matter and antimatter completely annihilate each other? How come we ended up with a little more matter? This delightful mystery is known as baryon asymmetry.

We do have a few ideas, and by we, I mean some giant brained crackerjacks have come up with a few plausible options. The most popular is that somehow antimatter behaves a little differently than matter. This could cause an imbalance between matter and antimatter. After particles collided in the early universe, there would still be matter left over, hence the matter we observe.

Another idea is that the observable universe just happens to be in a region dominated by matter. Other parts of the multiverse could have observable universes dominated by antimatter. Baryon asymmetry is one of the big mysteries of modern cosmology.

Zero Gravity Flight — Stephen Hawking, weightless (courtesy Zero Gravity Corporation)

There is an even crazier idea. Antimatter might have anti-gravity. In other words, an atom of anti-hydrogen would fall up instead of down. If that is the case, then matter and antimatter would repel each other, and you might have matter universes and antimatter universes that are forever separate.There have been some initial experiments to test this idea, but so far there have been no conclusive results.

What do you think? Where’s all our antimatter and how do we track it down? I’d sure love to bring some home and show my friends…

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November 13, 2014March 1, 2017 by Fraser Cain

What’s Causing The Universe To Expand?

We’ve all heard that the Universe is expanding, but why is it expanding? What’s the force pushing everything outwards?

If still you don’t know that we live in an expanding Universe, then I’m clearly not doing my job.

And so once more, with feeling… the Universe is expanding. But that certainly doesn’t answer all the questions that go along with the it.

Like what’s the Universe expanding into? Which we did in another video, which I’ll list at the end of this episode. You might also want to know why is the Universe expanding? What’s making this happen? Did it give up its gym membership? Did it sign up for the gallon of ice cream of the month club? Has it completely embraced the blerch?

Edwin Hubble, the astronomer made famous by being named after a space telescope, provided the definitive evidence that the Universe was expanding. Observing distant galaxies, he observed they were fleeing outwards, in fact he was able to come up with calculations to show just how fast they were moving away from us.

Or to be more precise, he was able to show how fast all the galaxies are moving away from each other. Which was your question! Just like a minute ago! See you’re just as smart as Hubble!

So up until about 15 years ago, the only answer was momentum. The idea was that the Universe received all the energy it needed for its expansion in the first few moments after the Big Bang.

Imagine the beginning of the Universe, BOOM, like an explosion from a gun. And all the rest of the expansion is the Universe coasting outwards. For the longest time, astronomers were trying to figure out what this momentum would mean for the future of the Universe.

Would the mutual gravity of all the objects in the Universe cause it to slow to a halt at some point in the distant future, or maybe even collapse in on itself, leading to a Big Crunch? Or just clump up in piles and stay on the couch all summer because it’s maybe a little lazy and isn’t ready to start going back to the gym yet?

In 1999, astronomers discovered something completely unexpected… dark energy. As they were doing their observations to figure out exactly how the Universe would coast to a stop, they discovered that it’s actually speeding up. It’s as if that bullet is actually a rocket and it’s accelerating.

Now it appears that the Universe will not only expand forever, but the speed of its expansion will continue to accelerate faster and faster. So what’s causing this expansion? Currently, we believe it’s mostly momentum left over from the Big Bang, and the force of dark energy will be accelerating this expansion. Forever.

How do you feel about a rapidly accelerating expanding Universe? Tell us in the comments below.

And if you like what you see, come check out our Patreon page and find out how you can get these videos early while helping us bring you more great content!

November 6, 2014March 1, 2017 by Fraser Cain

When Did the First Stars Form?

Shortly after the Big Bang, the Universe had cooled to the point that the first stars could form out of the primordial hydrogen. How long did it take, and what did these first stars like?

Hydrogen soup. Doesn’t that sound delicious? Perhaps not for humans, but certainly for the first stars!

Early in the Universe, in a spectacular show of stellar soupification, clouds of hydrogen atoms gathered together. They combined with one another. The collected mass got bigger and bigger, and after a time, ignition. The first stars were alive!

Well, alive in the sense that they were burning – not that they had feelings or knew what was going on, or had opinions, or were beginning to write would what would eventually become the first Onion article or anything.

But where did all that gas come from, and can we spot the evidence of those long-ago stars today? As you know, the Big Bang got our Universe off to a speedy start of expansion. It then took 400,000 years for us to see any light at all. Protons and electrons and other small particles were floating around, but it was far too hot for them to interact.

Once the power of the Big Bang finally faded, those protons and electrons paired up and created hydrogen. This is called, rather uninventively, “recombination”. I’d rather just call it hydrogen soup. We’ve got energy. But what is the secret ingredient that sparked these stars? It was just that soup clumping together over time.

A map of the faint microwave radiation left over after the big bang shows superclusters (red circles) and supervoids (blue circles). Credit: B. Granett, M. Neyrinck, I. Szapudi

We can’t say to the minute when the first stars formed, but we have a pretty good idea. The Wilkinson Microwave Anisotropy Probe, aka WMAP examined what happened when these clouds of hydrogen molecules got together, creating tiny temperature differences of only a millionth of a degree.

Over time, gravity began to yank matter from spots of lower density into the higher-density regions, making the clumps even bigger. Fantastically bigger. So big that about 200 million years after the clumps were formed, it was possible for these hydrogen molecules to ram into each other at very high speeds.

This process is called nuclear fusion. On Earth, it’s a way to produce energy. Same goes for a star. With enough nuclear reactions happening, the cloud of gas compresses and creates a glow. And these stars weren’t tiny – they were monsters! NASA says the first stars were 30 to 300 times as massive as the sun, shining millions of times brighter.

The supernova that produced the Crab Nebula was detected by naked-eye observers around the world in 1054 A.D. This composite image uses data from NASA’s Great Observatories, Chandra, Hubble, and Spitzer, to show that a superdense neutron star is energizing the expanding Nebula by spewing out magnetic fields and a blizzard of extremely high-energy particles. The Chandra X-ray image is shown in light blue, the Hubble Space Telescope optical images are in green and dark blue, and the Spitzer Space Telescope’s infrared image is in red. The size of the X-ray image is smaller than the others because ultrahigh-energy X-ray emitting electrons radiate away their energy more quickly than the lower-energy electrons emitting optical and infrared light. The neutron star is the bright white dot in the center of the image. — The supernova that produced the Crab Nebula was detected by naked-eye observers around the world in 1054 A.D. This composite image uses data from NASA’s Great Observatories, Chandra, Hubble, and Spitzer.

But this flashy behavior came at a price, because in only a few million years, the stars grew unstable and exploded into supernovae. These stars weren’t only exploding. They were also altering the soup around them. They were big emitters of ultraviolet light. It’s a very energetic wavelength, best known for causing skin cancer.

So, this UV light struck the hydrogen surrounding the stars. This split the atoms apart into electrons and protons again, leaving quite the mess in space. But it’s through this process that we can learn more about these earliest stars.The stars are long gone, but like a criminal fleeing the scene, they left a pile of evidence behind for their existence. Splitting these atoms was their evidence. This re-ionization is one key piece of understanding how these stars came to be.

So it was an action-packed time for the universe, with the Big Bang, then the emergence of soup and then the first stars. It’s quite an exciting start for our galactic history.

What do you think the first stars looked like?

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October 23, 2014March 1, 2017 by Fraser Cain

Why Can’t We See the Big Bang?

Since telescopes let us look back in time, shouldn’t we be able to see all the way back to the very beginning of time itself? To the moment of the Big Bang?

You’ve probably heard that looking out into space is like looking back in time. As it takes light 1 second to get from the Moon to us. Whenever we view it, we’re seeing it 1 second in the past. The Sun is 8 light minutes away, and the light we see from it is from 8 minutes into the past.

A better example might be Andromeda, it’s 2.5 million light years away… and you guessed it, we’re seeing it 2.5 million years in the past. Since the Big Bang happened 13.7 billion years ago, using this idea, shouldn’t we be able look all the way back to the beginning of time, even if we’ve misplaced the key to our Tardis?

At the very beginning of the Universe, seconds after the Big Bang, everything was mushed together. Energy and matter were the same thing. Dogs and cats lived together. There was no difference between light and radiation, it was all just one united force.

You couldn’t see it, because light didn’t actually exist. There were no such thing as photons.

However, if you’re still insisting there’s no such thing as photons, you might want to check yourself. After these things started to separate. Photons and particles became actual things. Electromagnetism and the weak nuclear force split off and formed new bands, but could never quite get the momentum of the original lineup.

By the end of the first second, neutrons and protons were around, and they were getting mashed by the intense heat and pressure into the first elements. But you still couldn’t see that because the whole Universe was like the inside of a star. Everything was opaque. It was Scarlett Johansson hot, and too crazy to form stable atoms with electrons as we see today.

Artist's conception of Planck, a space observatory operated by the European Space Agency, and the cosmic microwave background. Credit: ESA and the Planck Collaboration - D. Ducros — Artist’s conception of Planck, a space observatory operated by the European Space Agency, and the cosmic microwave background. Credit: ESA and the Planck Collaboration – D. Ducros

After the Universe was about 380,000 years old, it had cooled down to the point that proper atoms could form. This is the moment when light could finally move, and travel distances across the Universe to you and get caught up in your light buckets. In fact, this light is known as the cosmic microwave background radiation.

So, how come we don’t see all this freed light in all directions with our eyes? It’s because the region of space where it exists is so far away, and travelling away from us so quickly. The light’s wavelengths have been stretched out to the point that light has been turned into microwaves. It’s only with sensitive radio telescopes and space missions that astronomers can even detect it.

Unfortunately, we’ll never be able to see the Big Bang. Even though we’re looking back in time, right to the edge of the observable Universe, it’s just beyond our reach. If you could look at the Universe at any point in time, what would it be? Tell us in the comments below.

And if you like what you see, come check out our Patreon page and find out how you can get these videos early while helping us bring you more great content!

March 24, 2014December 23, 2015 by Jason Major

Cosmologists Cast Doubt on Inflation Evidence

Some physicists still have questions on the true origin of the BICEP2 findings...

It was just a week ago that the news blew through the scientific world like a storm: researchers from the BICEP2 project at the South Pole Telescope had detected unambiguous evidence of primordial gravitational waves in the cosmic microwave background, the residual rippling of space and time created by the sudden inflation of the Universe less than a billionth of a billionth of a second after the Big Bang. With whispers of Nobel nominations quickly rising in the science news wings, the team’s findings were hailed as the best direct evidence yet of cosmic inflation, possibly even supporting the existence of a multitude of other universes besides our own.

That is, if they really do indicate what they appear to. Some theorists are advising that we “put the champagne back in the fridge”… at least for now.

Theoretical physicists and cosmologists James Dent, Lawrence Krauss, and Harsh Mathur have submitted a brief paper (arXiv:1403.5166 [astro-ph.CO]) stating that, while groundbreaking, the BICEP2 Collaboration findings have yet to rule out all possible non-inflation sources of the observed B-mode polarization patterns and the “surprisingly large value of r, the ratio of power in tensor modes to scalar density perturbations.”

“However, while there is little doubt that inflation at the Grand Unified Scale is the best motivated source of such primordial waves, it is important to demonstrate that other possible sources cannot account for the current BICEP2 data before definitely claiming Inflation has been proved. “

– Dent, Krauss, and Mathur (arXiv:1403.5166 [astro-ph.CO])

The history of the universe starting the with the Big Bang. Image credit: grandunificationtheory.com

Inflation may very well be the cause — and Dent and company state right off the bat that “there is little doubt that inflation at the Grand Unified Scale is the best motivated source of such primordial waves” — but there’s also a possibility, however remote, that some other, later cosmic event is responsible for at least some if not all of the BICEP2 measurements. (Hence the name of the paper: “Killing the Straw Man: Does BICEP Prove Inflation?”)

Not intending to entirely rain out the celebration, Dent, Krauss, and Mathur do laud the BICEP2 findings as invaluable to physics, stating that they “will be very important for constraining physics beyond the standard model, whether or not inflation is responsible for the entire BICEP2 signal, even though existing data from cosmology is strongly suggestive that it does.”

Now I’m no physicist, cosmologist, or astronomer. Actually I barely passed high school algebra (and I have the transcripts to prove it) so if you want to get into the finer details of this particular argument I invite you to read the team’s paper for yourself here and check out a complementary article on The Physics arXiv Blog.

And so, for better or worse (just kidding — it’s definitely better) this is how science works and how science is supposed to work. A claim is presented, and, regardless of how attractive its implications may be, it must stand up to any other possibilities before deemed the decisive winner. It’s not a popularity contest, it’s not a beauty contest, and it’s not up for vote. What it is up for is scrutiny, and this is just an example of scientists behaving as they should.

Still, I’d keep that champagne nicely chilled.

Source: The Physics arXiv Blog

_________

Want to read more about the BICEP2 findings from actual physicists? Read more in an article by Peter Coles, see what Matthew Francis has to say in his article on arstechnica here, and watch a video by Sean Carroll on PBS News Hour.

March 17, 2014April 26, 2016 by Brian Koberlein

We’ve Discovered Inflation! Now What?

Polarization patterns imprinted in the CMB. Image Credit: CfA

Days like these make being an astrophysicist interesting. On the one hand, there is the annoucement of BICEP2 that the long-suspected theory of an inflationary big bang is actually true. It’s the type of discovery that makes you want to grab random people off the street and tell them what an amazing thing the Universe is. On the other hand, this is exactly the type of moment when we should be calm, and push back on the claims made by one research team. So let’s take a deep breath and look at what we know, and what we don’t.

Multiverse Theory — Inflation could mean our Universe is just one of many. Credit: Florida State University

First off, let’s dispel a few rumors. This latest research is not the first evidence of gravitational waves. The first indirect evidence for gravitational waves was found in the orbital decay of a binary pulsar by Russell Hulse and Joseph Taylor, for which they were awarded the Nobel prize in 1993. This new work is also not the first discovery of polarization within the cosmic microwave background, or even the first observation of B-mode polarization. This new work is exciting because it finds evidence of a specific form of B-mode polarization due to primordial gravitational waves. The type of gravitational waves that would only be caused by inflation during the earliest moments of the Universe.

It should also be noted that this new work hasn’t yet been peer reviewed. It will be, and it will most likely pass muster, but until it does we should be a bit cautious about the results. Even then these results will need to be verified by other experiments. For example, data from the Planck space telescope should be able to confirm these results assuming they’re valid.

That said, these new results are really, really interesting.

What the team did was to analyze what is known as B-mode polarization within the cosmic microwave background (CMB). Light waves oscillate perpendicular to their direction of motion, similar to the way water waves oscillate up and down while they travel along the surface of water. This means light can have an orientation. For light from the CMB, this orientation has two modes, known as E and B. The E-mode polarization is caused by temperature fluctuations in the CMB, and was first observed in 2002 by the DASI interferometer.

The B-mode polarization can occur in two ways. The first way is due to gravitational lensing. The first is due to gravitational lensing of the E-mode. The cosmic microwave background we see today has travelled for more than 13 billion years before reaching us. Along its journey some of it has passed close enough to galaxies and the like to be gravitationally lensed. This gravitational lensing twists the polarization a bit, giving some of it a B-mode polarization. This type was first observed in July of 2013. The second way is due to gravitational waves from the early inflationary period of the universe. As inflationary period occurred, then it produced gravitational waves on a cosmic scale. Just as the gravitational lensing produces B-mode polarization, these primordial gravitational waves produce a B-mode effect. The discovery of primordial wave B-mode polarization is what was announced today.

The effect of early inflation on the size of the universe. Credit: NASA/COBE

Inflation has been proposed as a reason for why the cosmic microwave background is as uniform as it is. We see small fluctuations in the CMB, but not large hot or cold spots. This means the early Universe must have been small enough for temperatures to even out. But the CMB is so uniform that the observable universe must have been much smaller than predicted by the big bang. However, if the Universe experienced a rapid increase in size during its early moments, then everything would work out. The only problem was we didn’t have any direct evidence of inflation.

Assuming these new results hold up, now we do. Not only that, we know that inflation was stronger than we anticipated. The strength of the gravitational waves is measured in a value known as r, where larger is stronger. It was found that r = 0.2, which is much higher than anticipated. Based upon earlier results from the Planck telescope, it was expected that r < 0.11. So there seems to be a bit of tension with earlier findings. There are ways in which this tension can be resolved, but just how is yet to be determined.

So this work still needs to be peer reviewed, and it needs to be confirmed by other experiments, and then the tension between this result and earlier results needs to be resolved. There is still much to do before we really understand inflation. But overall this is really big news, possibly even Nobel prize worthy. The results are so strong that it seems pretty clear we have direct evidence of cosmic inflation, which is a huge step forward. Before today we only had physical evidence back to when the universe was about a second old, at a time when nucleosynthesis occurred. With this new result we are now able to probe the Universe when it was less than 10 trillion trillion trillionths of a second old.

Which is pretty amazing when you think about it.

March 17, 2014April 26, 2016 by Shannon Hall

Landmark Discovery: New Results Provide Direct Evidence for Cosmic Inflation

The BICEP telescope located at the south pole. Image Credit: CfA / Harvard

Astronomers have announced Nobel Prize-worthy evidence of primordial gravitational waves — ripples in the fabric of spacetime — providing the first direct evidence the universe underwent a brief but stupendously accelerated expansion immediately following the big bang.

“The implications for this detection stagger the mind,” said co-leader Jamie Bock from Caltech. “We are measuring a signal that comes from the dawn of time.”

BICEP2 (Background Imaging of Cosmic Extragalactic Polarization) scans the sky from the south pole, looking for a subtle effect in the cosmic microwave background (CMB) — the radiation released 380,000 years after the Big Bang when the universe cooled enough to allow photons to travel freely across the cosmos.

The CMB fills every cubic centimeter of the observable universe with approximately 400 microwave photons. The so-called afterglow of the big bang is nearly uniform in all directions, but small residual variations (on the level of one in 100,000) in temperature show a specific pattern. These irregularities match what would be expected if minute quantum fluctuations had ballooned to the size of the observable universe today.

So astronomers dreamed up the theory of inflation — the epoch immediately following the big bang (10^-34 seconds later) when the universe expanded exponentially (by at least a factor of 10²⁵) — causing quantum fluctuations to magnify to cosmic size. Not only does inflation help explain why the universe is so smooth on such massive scales, but also why it’s flat when there’s an infinite number of other possible curvatures.

While inflation is a pillar of big bang cosmology, it has remained purely a theoretical framework. Many astronomers don’t buy it as we can’t explain what physical mechanism would have driven such a massive expansion, let alone stop it. The results announced today provide a strong case in support of inflation.

In Depth: We’ve Discovered Inflation! Now What?

The trick is in looking at the CMB where inflation’s signature is imprinted as incredibly faint patterns of polarized light — some of the light waves have a preferred plane of vibration. If a gravitational wave passes through the fabric of spacetime it will squeeze spacetime in one direction (making it hotter) and stretch it in another (making it cooler). Inflation will then amplify these quantum fluctuations into a detectable signal: the hotter and therefore more energetic photons will be visible in the CMB, leaving a slight polarization imprint.

This effect will create two distinct patterns: E-modes and B-modes, which are differentiated based on whether or not they have even or odd parity. In simpler terms: E-mode patterns will look the same when reflected in a mirror, whereas B-mode patterns will not.

E-modes have already been extensively detected and studied. While both are the result of primordial gravitational waves, E-modes can be produced through multiple mechanisms whereas B-modes can only be produced via primordial gravitational waves. Detecting the latter is a clean diagnostic — or as astronomers are putting it: “smoking gun evidence” — of inflation, which amplified gravitational waves in the early Universe.

“The swirly B-mode pattern is a unique signature of gravitational waves because of their handedness. This is the first direct image of gravitational waves across the primordial sky,” said co-leader Chao-Lin Kuo from Stanford University, designer of the BICEP2 detector.

The team analyzed sections of the sky spanning one to five degrees (two to 10 times the size of the full moon) for more than three years. They created a unique array of 512 detectors, which collectively operate at a frosty 0.25 Kelvin. This new technology enabled them to make detections at a speed 10 times faster than before.

The results are surprisingly robust, with a 5.9 sigma detection. For comparison, when particle physicists announced the discovery of the Higgs Boson in July, 2012 they had to reach at least a 5 sigma result, or a confidence level of 99.9999 percent. At this level, the chance that the result is erroneous due to random statistical fluctuations is only one in a million. Those are pretty good odds.

While the team was careful to rule out any errors, it will be crucial for another team to verify these results. The Planck spacecraft, which has been producing exquisite measurements of the CMB, will be reporting its own findings later this year. At least a dozen other teams have also been searching for this signature.

“This work offers new insights into some of our most basic questions: Why do we exist? How did the universe begin?” commented Harvard theorist Avi Loeb. “These results are not only a smoking gun for inflation, they also tell us when inflation took place and how powerful the process was.”

Not only does inflation succeed in explaining the origin of cosmic structure — how the cosmic web formed from the smooth aftermath of the big bang — but it makes wilder predictions as well. The model seems to produce not just one universe, but rather an ensemble of universes, otherwise known as a multiverse. This collection of universes has no end and no beginning, continuing to pop up eternally.

Today’s results provide a stronger case for “eternal inflation,” which gives a new perspective on our desolate place within the cosmos. Not only do we live on a small planet orbiting one star out of hundreds of billions, in one galaxy out of hundreds of billions, but our entire universe may just be one bubble out of a vast cosmic ocean of others.

The detailed paper may be found here.
The full set of papers are here.
An FAQ summarizing the data is here.

March 12, 2014March 8, 2017 by Fraser Cain

What Is The Cosmic Microwave Background Radiation?

The Cosmic Microwave Background Radiation is the afterglow of the Big Bang; one of the strongest lines of evidence we have that this event happened. UCLA’s Dr. Ned Wright explains.

“Ok, I’m Ned Wright, and I’m a professor of physics and astronomy at UCLA, and I work on infrared astronomy and cosmology.”

How useful is the cosmic microwave background radiation?

“Well, the most important information we get is from the cosmic microwave background radiation come from, at the lowest level, is it’s existence. When I started in astronomy, it wasn’t 100 percent certain that the Big Bang model was correct. And so with the prediction of a cosmic microwave background from the Big Bang and the prediction of no cosmic microwave background from the competing theory, the steady state, that was a very important step in our knowledge.”

“And then the second aspect of the cosmic microwave background that is very important, is that it’s spectrum is extremely similar to a black body. And so, by being a black body means that universe relatively smoothly transitioned from being opaque to being transparent, and then we actually see effectively an isothermal cavity when we look out, so it looks very close to a black body.”

“And the fact that we are moving through the universe can be measured very precisely by looking at what is called the dipole anisotropy of the microwave background. So one side of the sky is slightly hotter (about 3 millikelvin hotter) and one side of the sky – the opposite side of the sky – is slightly colder (about 3 millikelvin colder), so that means that we are moving at approximately a tenth of a percent of the speed of light. And in fact we now know very precisely what that value is – it’s about 370 kilometers per second. So that’s our motion, the solar system’s motion, through the universe.”

“An then the final piece of information we’re getting from the microwave background now, in fact the Planck satellite just gave us more information along these lines is measurement of the statistical pattern of the very small what I call anisotropies or little bumps and valleys in the temperature. So in addition to the 3 millikelvin difference, we actually have plus or minus 100 microkelvin difference in the temperature from different spots. And so, when you look at these spots, and look at their detailed pattern, you can actually see a very prominent feature, which is there’s about a one and a half degree preferred scale, and that’s what’s caused by the acoustic
waves that are set up by the density perturbations early in the history of the universe, and how far they could travel before the universe became transparent. And that’s a very strong indicator about the universe.”

What does it tell us about dark energy?

“The cosmic microwave background actually has this pattern on a half degree scale, and that gives you effectively a line of position, as you have with celestial navigation where you get a measurement of one star with a sextant, then you get a line on the map where you are. But you can look at the same pattern – the acoustic wave setup in the universe, and you see that in the galaxy’s distribution a lot more locally. We’re talking about galaxies, so it might be a billion light years away, but to cosmologists, that’s local. And these galaxies also show the same wave-like pattern, and you can measure that angle at scale locally and compare it to what you see in history and that gives you the crossing line of position. And that really tells us where we are in the universe, and how much stuff there is and it tells us that we have this dark energy which nobody really understands what it is, but we know what it’s doing. It’s making the universe accelerate in it’s expansion.”

March 6, 2014March 8, 2017 by Fraser Cain

Why Is This A Special Time For The Universe?

You might be surprised to know that you’re living in a very special time in the Universe. And in the far future, our descendant astronomers will wish they could live in such an exciting time Let’s find out why.

You might be interested to know that you are living in a unique important and special time in the age of the Universe. Our view of the night sky won’t be around forever, in fact, as we think about the vast time that lies ahead, our time in the Universe will sound very special.

Astronomers figure the Universe has been around for 13.8 billion years. Everything in the entire Universe was once collected together into a singularity of space and time. And then, in a flash, Big Bang. Within a fraction of a second, the fundamental forces of the Universe came into existence, followed by the earliest types of matter and energy. For a few minutes, the entire Universe was like a core of a star, fusing hydrogen into helium. Approximately 377,000 years after the Big Bang, the entire Universe had cooled to the point that it became transparent. We see this flash of released light as the Cosmic Microwave Background Radiation.

Over the next few billion years, the first stars and galaxies formed, leading to the large scale structures of the Universe. These new galaxies with their furious star formation would have been an amazing sight. It would have been a very special time in the Universe, but it’s not our time.

Over the next few billion years, the Universe continued to expand. And it was during this time that the mysterious force called dark energy crept in, further driving the expansion of the Universe. We don’t know what dark energy is, but we know it’s a constant pressure that’s accelerating the expansion of the Universe.

As the volume of the Universe increases, the rate of its expansion increases. And over vast periods of time, it’ll make the Universe unrecognizable from what we see today. The further we look out into space, the faster galaxies are moving away from us. There are galaxies moving away from us faster than the speed of light. In other words, the light from those galaxies will never reach us.

The Universe 1.9 billion years after the Big Bang. Credit: Alvaro Orsi, Institute for Computational Cosmology, Durham University.

As dark energy increases, more and more galaxies will cross this cosmic horizon, invisible to us forever. And so, we can imagine a time in the far future, where the Cosmic Microwave Background Radiation has been stretched away until it’s undetectable. And eventually there will be a time when there will be no other galaxies visible in the night sky. Future astronomers will see a Universe without a cosmological history. There will be no way to know that there was ever a Big Bang, that there was ever a large scale structure to the Universe.

So how long will this be? According to Dr. Lawrence Krauss and Robert J. Scherrer, in as soon as 100 billion years, there will be no way to see other galaxies and calculate their velocity away from us. That sounds like a long time, but there are red dwarf stars that could live for more than a trillion years. We will have lost our history forever.

Cherish and make the most of these next hundred billion years. Keep our history alive and remember to tell our great great grandchildren and their robotic companions the tales of a time when we knew about the Big Bang.

What about you? What would you go see if you could witness any astronomical event in the history of the universe?

February 15, 2014December 23, 2015 by Jason Major

NOvA Experiment Nabs Its First Neutrinos

The NUmI (Neutrinos from the Main Injector) horn at Fermilab, which fires protons that degrade into neutrinos. (Image: Caltech)

Neutrinos are some of the most abundant, curious, and elusive critters in particle physics. Incredibly lightweight — nigh massless, according to the Standard Model — as well as chargeless, they zip around the Universe at the speed of light and they don’t interact with any other particles. Some of them have been around since the Big Bang and, just as you’ve read this, trillions of them have passed through your body (and more are on the way.) But despite their ubiquitousness neutrinos are notoriously difficult to study precisely because they ignore pretty much everything made out of anything else. So it’s not surprising that weighing a neutrino isn’t as simple as politely asking one to step on a scale.

Thankfully particle physicists are a tenacious lot, including the ones at the U.S. Department of Energy’s Fermilab, and they aren’t giving up on their latest neutrino safari: the NuMI Off-Axis Electron Neutrino Appearance experiment, or NOvA. (Scientists represent neutrinos with the Greek letter nu, or v.) It’s a very small-game hunt to catch neutrinos on the fly, and it uses some very big equipment to do the job. And it’s already captured its first neutrinos — even before their setup is fully complete.

Created by smashing protons against graphite targets in Fermilab’s facility just outside Chicago, Illinois, resulting neutrinos are collected and shot out in a beam 500 miles northwest to the NOvA far detector in Ash River, Minnesota, located along the Canadian border. The very first beams were fired in Sept. 2013, while the Ash River facility was still under construction.

One of the first detections by NOvA of Fermilab-made neutrinos (Image courtesy of NOvA collaboration)

“That the first neutrinos have been detected even before the NOvA far detector installation is complete is a real tribute to everyone involved,” said University of Minnesota physicist Marvin Marshak, Ash River Laboratory director. “This early result suggests that the NOvA collaboration will make important contributions to our knowledge of these particles in the not so distant future.”

The 500-mile (800 km) path of the NOvA neutrino beam (Fermilab) — The 500-mile (800 km) subterranean path of the NOvA neutrino beam (Fermilab)

The beams from Fermilab are fired in two-second intervals, each sending billions of neutrinos directly toward the detectors. The near detector at Fermilab confirms the initial “flavor” of neutrinos in the beam, and the much larger far detector then determines if the neutrinos have changed during their three-millisecond underground interstate journey.

Again, because neutrinos don’t readily interact with ordinary particles, the beams can easily travel straight through the ground between the facilities — despite the curvature of the Earth. In fact the beam, which starts out 150 feet (45 meters) below ground near Chicago, eventually passes over 6 miles (10 km) deep during its trip.

According to a press release from Fermilab, neutrinos “come in three types, called flavors (electron, muon, or tau), and change between them as they travel. The two detectors of the NOvA experiment are placed so far apart to give the neutrinos the time to oscillate from one flavor to another while traveling at nearly the speed of light. Even though only a fraction of the experiment’s larger detector, called the far detector, is fully built, filled with scintillator and wired with electronics at this point, the experiment has already used it to record signals from its first neutrinos.”

The 50-foot (15 m) tall detector blocks are filled with a liquid scintillator that’s made of 95% mineral oil and 5% liquid hydrocarbon called pseudocumene, which is toxic but “imperative to the neutrino-detecting process.” The mixture magnifies any light that hits it, allowing the neutrino strikes to be more easily detected and measured. (Source)

“NOvA represents a new generation of neutrino experiments,” said Fermilab Director Nigel Lockyer. “We are proud to reach this important milestone on our way to learning more about these fundamental particles.”

One of NOvA's 28 detectors (Fermilab) — One of NOvA’s 28 far detector blocks (Fermilab)

After completion this summer NOvA’s near and far detectors will weigh 300 and 14,000 tons, respectively.

The goal of the NOvA experiment is to successfully capture and measure the masses of the different neutrino flavors and also determine if neutrinos are their own antiparticles (they could be the same, since they lack specific charge.) By comparing the oscillations (i.e., flavor changes) of muon neutrino beams vs. muon antineutrino beams fired from Fermilab, scientists hope to determine their mass hierarchy — and ultimately discover why the Universe currently contains much more matter than antimatter.

Once the experiment is fully operational scientists expect to catch a precious few neutrinos every day — about 5,000 total over the course of its six-year run. Until then, they at least now have their first few on the books.

“Seeing neutrinos in the first modules of the detector in Minnesota is a major milestone. Now we can start doing physics.”
– Rick Tesarek, Fermilab physicist

Learn more about the development and construction of the NoVA experiment below:

(Video credit: Fermilab)

Find out more about the NOvA research goals here.

Source: Fermilab press release

The NOvA collaboration is made up of 208 scientists from 38 institutions in the United States, Brazil, the Czech Republic, Greece, India, Russia and the United Kingdom. The experiment receives funding from the U.S. Department of Energy, the National Science Foundation and other funding agencies.