Get Your Telescopes Ready: Neptune Is Coming
“Because of the periodic motions of the planets, Mars and Neptune had a close encounter just two years ago, but this year’s conjunction blows that one away in terms of proximity and viewing conditions. With a new Moon on December 7th, clear skies and the Geminid meteor shower growing towards its December 13th peak, it’s a great night to be outside for stargazing. Bring even a small telescope or a pair of binoculars with you, though, and the spectacular, blue sight of Neptune will be your reward.
For a few minutes of effort, you’ll see what no human prior to Galileo ever saw, except unlike Galileo, you won’t mistakenly record that you observed a fixed star. Instead, you’ll know you’re viewing the 8th and outermost planet in our Solar System, a planet that nobody knew existed a mere two centuries ago. This December 7th, we all have the opportunity to become astronomers. Make your chance count.”
On December 7th, 2018, a spectacular astronomical event will occur, but you won’t notice without binoculars or a telescope. Mars and Neptune will achieve an extremely close conjunction, separated by a mere 0.03 degrees at the moment of their closest approach. If you look at easily-identifiable Mars at that moment through binoculars or a telescope, you might see a faint, blue dot that appears to be a satellite companion of Mars. Only it’s not; it’s brilliant, blue Neptune, approximately 30 times as far away as our red neighbor! Galileo was the first to see Neptune, but he misidentified it for a fixed star. More than 200 years later, it remained undiscovered. But on December 7th, some 400 years later, you’ll have the opportunity of a lifetime that most humans will never get: the chance to see Neptune for yourself.
Next month, we’ll all have the chance to be astronomers, and to see a spectacular sight that generations of people never got. Make it count.
Physicists Used Einstein’s Relativity To Successfully Predict A Supernova Explosion
“When the lens and a background source align in a particular fashion, quadruple images will result. With slightly different light-travel paths, the brightness and arrival time of each image is unique. In November 2014, a quadruply-lensed supernova was observed, showcasing exactly this type of alignment. Although a single galaxy caused the quadruple image, that galaxy was part of a huge galaxy cluster, exhibiting its own strong lensing effects. Elsewhere in the cluster, two additional images of the same galaxy also appear.”
We normally think of light traveling in a straight line, but that’s only true if your space is flat. In the real Universe, mass and matter not only exist, but clump together into massive structures like galaxies, quasars, and galaxy clusters. When a background source of light passes through these foreground masses, the light can get bent and distorted into multiple images that are magnified and arrive at slightly different times. If an event occurs in one such image, we can predict, based on General Relativity, cluster dynamics, and dark matter, when that event will appear in the other images.
In November 2014, we discovered a multiply-lensed supernova, and predicted where and when it would appear in the other images. Einstein and dark matter both win again!
Ask Ethan: Are Quantum Fields Real?
“I would be very interested in a post about quantum fields. Are they generally/universally believed to be real and the most fundamental aspect of our universe or just a mathematical construct? I’ve read that there are 24 fundamental quantum fields: 12 fields for fermions and 12 for bosons. But I’ve also read about quantum fields for atoms, molecules, etc. How does that work? Does everything emerge from these 24 fields and their interactions?”
When you think about the Universe, you probably think about it in a very particular fashion. There’s spacetime: the backdrop upon which the matter in the Universe exists, and then there are particles and antiparticles, which make up everything we can conceive of in the cosmos. Only, the quantum nature of reality is very different from this intuitive picture, and quantum field theory goes a few steps farther than even the unintuitive pictures we have in our heads. What if Heisenberg uncertainty, the Pauli exclusion principle, wave-particle duality and more were all just manifestations of something very basic: quantum fields themselves?
Quantum fields, believe it or not, are the most real thing we know of in the Universe. Here’s the science of how they make up our Universe.
How Many Fundamental Constants Does It Take To Explain The Universe?
“Our Universe is an intricate, amazing place, and yet our greatest hopes of a unified theory — a theory of everything — seek to decrease the number of fundamental constants we need. In reality, though, the more we learn about the Universe, the more parameters we’re learning it takes to fully describe it. It’s important to recognize where we are and what it takes, today, to describe the entirety of what’s known.
But we still don’t know everything, and so it’s also important to keep searching for a more complete paradigm. If we’re successful, it will give us absolutely everything the Universe has in it, including solutions to our current mysteries. The hope of many, but not a requirement, is that the Universe will wind up being simpler than we currently know. Right now, unfortunately, anything simpler than what’s been put forth here is too simple to work. Our Universe may not be elegant, after all.”
Think about everything that exists in our Universe. We have the four fundamental forces: gravity, electromagnetism, and the strong and weak nuclear forces. We have all the particles and antiparticles of the Standard Model; we have the bosons; we have the ways that particle behavior changes dependent on energy. We have hundreds of known composite particles and the ways that they interact, couple and decay. For everything that’s known, there are at least 26 fundamental constants required to explain the Universe on top of the laws of physics themselves, and still, they don’t give us everything.
Could there be a deeper explanation? Or are things only going to get messier from here? Here are the constants to describe what’s known so far!
This Is Why Sputnik Crashed Back To Earth After Only 3 Months
“But for the 25,000+ other satellites in low-Earth orbit, there is no controlled re-entry coming. Earth’s atmosphere will take them down, extending far beyond the artificial edge of space, or Kármán line, that we typically draw. If we were to cease launching satellites today, then in under a century, there would be no remaining trace of humanity’s presence in low-Earth orbit.
Sputnik 1 was launched in 1957, and just three months later, it spontaneously de-orbited and fell back to Earth. The particles from our atmosphere rise far above any artificial line we’ve drawn, affecting all of our Earth-orbiting satellites. The farther your perihelion is, the longer you can remain up there, but the harder it becomes to send-and-receive signals from here on the surface. Until we have a fuel-free technology to passively boost our satellites to keep them in a more stable orbit, Earth’s atmosphere will continue to be the most destructive force to humanity’s presence in space.”
On October 4th, 1957, the world changed forever with the launch of Sputnik 1. One of the common questions that astronomers get asked is whether we can still see it or not. The answer surprises most people: not only can’t we see it, but it crashed back to Earth just 3 months after launch, before the United States even launched its first successful satellite: Explorer 1. Moreover, the reason this happened wasn’t due to any technical flaw or malfunction, but due to the simple physical fact that Earth’s atmosphere doesn’t end where we erroneously and arbitrarily define the “edge of space” to be. Instead, atmospheric drag affects all satellites in low-Earth orbit, and will eventually take down everything from the International Space Station to the Hubble Space Telescope.
Come find out how this works, and learn why over 95% of everything we’ve ever put in space is doomed to come back to Earth by the century’s end.
What Was It Like When Galaxies Formed The Greatest Number Of Stars?
“The star-formation rate declined slowly and steadily for a few billion years, corresponding to an epoch where the Universe was still matter-dominated, just consisting of more processed and aged material. There were fewer mergers by number, but this was partially compensated for by the fact that larger structures were merging, leading to larger regions where stars formed.
But right around 6-to-8 billion years of age, the effects of dark energy began to make their presence known on the star formation rate, causing it to plummet precipitously. If we want to see the largest bursts of star formation, we have no choice but to look far away. The ultra-distant Universe is where star formation was at its maximum, not locally.”
In a myriad of locations, throughout our galaxy and almost all the galaxies in the known Universe, new stars form wherever a cloud of gas is triggered into collapsing. From the Orion Nebula to dozens of others in our own galaxy, new stars form thousands-at-a-time in regions all throughout our local neighborhood. But as spectacular as these sights are, they’re much, much rarer than they were a long time ago. In fact, we formed stars at a rate that was 30 times faster than today back when the Universe was young. For the last 11 billion years, we’ve been forming fewer and fewer stars everywhere we look.
The Universe is changing even today, and fewer and fewer stars are being newly created as time goes on. There are many reasons why; come learn them today!
Who Really Discovered The Expanding Universe?
“Recently, what was known for generations as “Hubble’s Law” has now been renamed the Hubble-Lemaître law. But the point shouldn’t be to give credit to individuals who’ve been dead for generations, but rather for everyone to understand how we know the rules that govern the Universe, and what they are. I, for one, would be just as happy to drop all the names from all the physical laws out there, and simply to refer to them as what they are: the redshift-distance relation. It wasn’t the work of just one or two people that led to this breakthrough in discovering the expanding Universe, but of all the scientists I named here and many others as well. At the end of the day, it’s our fundamental knowledge of how the Universe works that matters, and that’s the ultimate legacy of scientific research. Everything else is just a testament to the all-too-human foible of vainly grasping at glory.”
In science, we have a tendency to name theories, laws, equations, or discoveries after the individual who made the greatest contribution towards its development. For generations, we credited Edwin Hubble for discovering the expanding Universe, as his contributions in the 1920s were absolutely tremendous. However, history has not only revealed that Georges
discovered the very law we had named after Hubble two years prior, but that many other people made essential contributions to that realization. The expanding Universe didn’t come about solely because of Hubble’s discoveries, and perhaps we can do better than crediting just a single person.
Here are a slew of advances that led to and supported the expanding Universe, showing that history and science relies on contributions far richer than that of a lone, genius scientist.
An Ultra-Short History Of The Entire Universe
“This hot, primordial soup expanded and cooled, creating a slight asymmetry between matter (slightly more) and antimatter (slightly less). The cooling continued, nuclei formed, and eventually, so did neutral atoms.
These atoms clumped together in gravitationally overdense regions, forming the first stars after tens of millions of years.”
In the beginning, before even the Big Bang, all that we had was space and time, expanding rapidly according to the rules of cosmological inflation. Today, we’ve got an observable Universe full of stars and galaxies, tens of billions of light years across, with at least one instance of intelligent life: on Earth.
The story of how we got to be here was a mystery to philosophers, theologists and poets for all of human history, but advances during the last century have brought that from the realm of the speculative to firm, scientific knowledge. We understand, at least in broad strokes, how the Universe began, evolved, and came to be the way it is today, from before the Big Bang to human intelligence here on Earth.
Want to see what that entire story looks like in a mere 200 words? Come get it today!
Ask Ethan: When Do Black Holes Become Unstable?
“Is there a critical size for black hole stability? [A] 1012 kg [black hole] is already stable for a couple of billion years. However, a [black hole] in the range of 105 kg, could explode in a second, thus, definitely not stable… I guess there is a critical mass for a [black hole] where the flow of gained matter will equal to the Hawking evaporation?”
Wherever you have a black hole in the Universe, you have two competing processes. On the one hand, anything that crosses the event horizon, whether it’s normal matter, dark matter, or even pure energy, can never escape. If you fall in, you just add to the overall mass of the black hole, and grow it in size, too. But on the other hand, all black holes radiate away energy in the form of Hawking radiation, and that subtracts mass over time, shrinking your black hole. For all realistic-mass black holes, the rate-of-growth far outstrips the rate of mass loss, meaning they’ll grow for a very long time before they start to shrink.
But eventually, they will shrink. And although we think they don’t exist, a low-enough mass black hole would start shrinking today. Find out when black holes become unstable today!
This Is How We Will Discover The Most Distant Galaxy Ever
“Sometime in the distant past, likely when the Universe was less than 2% its current age, the very first galaxy of all formed when massive star clusters merged together, resulting in an unprecedented burst of star formation. The high-energy light from these stars struggles to escape, but the longer-wavelength light can penetrate farther through neutral atoms. The expansion of the Universe redshifts all the light, stretching it far beyond anything Hubble could potentially observe, but next-generation infrared telescopes should be able to catch it. And if we observe the right part of the sky, with the right instruments, for a sufficiently long time to reveal the right details about these objects, we’ll push back the cosmic frontier of the first galaxies even farther.
Somewhere, the most distant, first galaxy of all is out there, waiting to be discovered. As the 2020s approach, we can feel confident that we’ll not only shatter the current cosmic record-holder, but we know exactly how we’ll do it.”
13.8 billion years ago, our Universe as-we-know-it began with the hot Big Bang. There were no stars or galaxies back then; there weren’t even bound structures of any type. Everything was too energetic, and would immediately be destroyed by the unfathomably high temperatures and energies that every particle possessed. Yet, with time, the Universe expanded and cooled. Protons, nuclei, and neutral atoms formed; overdense regions gravitationally pulled-in mass and matter; stars were born, lived, died, and new stars were born in their aftermath. At some point, the first large star clusters merged together, passing a critical threshold and forming the first galaxy in the Universe.
That’s what we want to find. We’ve gone back to when the Universe was just 3% its present age, but that’s not enough. We must go father. We must find the first one. Here’s how we’ll do it.