Ask Ethan: How Does Quantum Physics Make Levitation Possible?
“I am fascinated about superconductivity and its associated Meissner effect it creates. From what I understand, the Meissner effect (when the magnetic field is expelled and levitation occurs) is created when there is zero electrical resistance. […] Is zero electrical resistance free flowing electrons? […] What actually causes the expulsion of the magnetic field that creates levitation?”
Imagine the following science-fiction scenario: you hop into a vehicle and accelerate up to cruising speed. All of a sudden, you push a button and you lift up off the road, levitating over it. You take your foot off the gas and the steering wheel, and instead of slowing down or losing control, you remain moving at a constant speed, following all the twists-and-turns of the road effortlessly.
It sounds like a crazy scenario, but there’s a quantum phenomenon that allows you to do exactly this: superconductivity! With the right type of superconductor and a properly-configured magnetic track, we can already make this a reality at liquid nitrogen temperatures.
How does it happen, and what will it take to turn this science-fiction dream into a reality? Get the answer today!
This Is How Dark Energy’s Main Competitor Failed
“The reason is simple: with the addition of enough extra free parameters, caveats, behaviors, or modifications to your theory, you can literally salvage any idea. As long as you’re willing to tweak what you’ve come up with sufficiently, you can never rule anything out. If you wanted to concoct a dusty explanation that mimicked the effects of dark energy, you could do it. At some point, though, you lose all physical motivation, and you’re coming up with multi-parameter explanations to explain an observation that a single free parameter — dark energy — gave you before you started tinkering with your dust theory.”
When we look out at the ultra-distant Universe, Type Ia supernovae are our most distant standard candle to work with. From billions or even tens of billions of light years away, we think we know the intrinsic brightnesses of these objects. So measure the apparent brightness, and you know how far away they are, right?
Well, not so fast. What if there’s dust or some other light-blocking phenomenon intervening? Could that mean that these objects are closer than we think, and therefore there’s no need for dark energy? It’s a great idea, and one that we investigated for many years, until the data convincingly showed that no, dust cannot work.
Want to find out why dark energy is real, and this isn’t due to the effects of dust? Have a look today!
Scientists Can’t Agree On The Expanding Universe
“The question of how quickly the Universe is expanding is one that has troubled astronomers and astrophysicists since we first expansion was occurring at all. It’s an incredible achievement that multiple, independent methods yield answers that are consistent to within 10%, but they don’t agree with each other, and that’s troubling.
If there’s an error in parallax, Cepheids, or supernovae, the expansion rate may truly be on the low end: 67 km/s/Mpc. If so, the Universe will fall into line when we identify our mistake. But if the Cosmic Microwave Background group is mistaken, and the expansion rate is closer to 73 km/s/Mpc, it foretells a crisis in modern cosmology. The Universe cannot have the dark matter density and initial fluctuations 73 km/s/Mpc would imply.
Either one team has made an unidentified mistake, or our conception of the Universe needs a revolution. I’m betting on the former.”
The Universe is expanding: the observations overwhelmingly support that. It’s consistent with Einstein’s General Relativity; it work with the framework of the Big Bang; it allows us to quantify and predict the ultimate fate of our Universe.
But how fast, then, is the Universe expanding?
Scientists can’t agree, because there are three different techniques you can use to measure it. Two agree; one doesn’t.
So what gives? This is the controversy driving astrophysicists nuts at the moment. Come learn what it’s all about, along with my hunch as to what the resolution will be!
Is There Really A Fourth Neutrino Out There In The Universe?
“Regardless of what the ultimate explanation is, it’s quite clear that the normal Standard Model, with three neutrinos that oscillate between electron/muon/tau types, cannot account for everything we’ve observed up to this point. The LSND results, once dismissed as a baffling experimental result that must surely be wrong, have been confirmed in a big way. With reactor deficiencies, MiniBooNe’s results, and three new experiments on the horizon to gather more data about these mysteriously misbehaving particles, we may be poised for a new revolution in physics.
The high-energy frontier is only one way we have of learning about the Universe on a fundamental level. Sometimes, we just have to know what the right question to ask truly is. By looking at the lowest-energy particles at different distances from where they’re generated, we just might take the next great leap in our knowledge of physics. Welcome to the era of the neutrino, which is taking us, at last, beyond the Standard Model.”
No matter how good, compelling, elegant, or successful our theories about the Universe are, they must always be confronted with experiments. If there’s a new, conflicting experimental result, it must be verified and validated independently to make sure it’s correct. Well, that was what the LSND experiment was for neutrinos and the Standard Model: an outlier that couldn’t be explained consistently with the other observations. After 16 years, the MiniBooNe experiment has released their final results: validating LSND and presenting a combined 6.0-sigma significance. Neutrinos don’t behave as they should.
Does that mean there’s a 4th neutrino? That one is sterile? That the Standard Model is wrong? It’s a fascinating topic, and you should get the full story today!
Atacama Dark Sky Retreat 2019 — Astro.Tours:
Huge announcement, world!
Do you want to:
-see the Southern Hemisphere’s night sky,
-visit ALMA, the world’s most power telescope array,
-visit Gemini Observatory’s 8-meter telescope,
-on an all-inclusive vacation,
Sign-ups start today!
Five Surprising Truths About Black Holes From LIGO
“1.) The largest merging black holes are the easiest to see, and they don’t appear to get larger than about 50 solar masses. One of the best things about looking for gravitational waves is that it’s easier to see them from farther away than it is for a light source. Stars appear dimmer in proportion to their distance squared: a star 10 times the distance is just one-hundredth as bright. But gravitational waves are dimmer in direct proportion to distance: merging black holes 10 times as far away produce 10% the signal.
As a result, we can see very massive objects to very great distances, and yet we don’t see black holes merging with 75, 100, 150, or 200+ solar masses. 20-to-50 solar masses are common, but we haven’t seen anything above that yet. Perhaps the black holes arising from ultra-massive stars truly are rare.”
Well, the LIGO and Virgo collaborations have put their head together to re-analyze the full suite of their scientific data, and guess what they found: a total of 11 merger events, including ten black hole-black hole mergers. Now that we’re in the double digits, we can actually start to say some incredibly meaningful things about what’s present in the Universe, what we’ve seen, and what that means for what comes next. Which black holes are the most common? How frequently do these mergers occur? What’s the highest-mass black hole binary that LIGO could detect? And how many black holes do we expect to find when run III starts up in 2019?
The answers are coming! Come see what we know so far, and learn five surprising truths about black holes, courtesy of our findings from LIGO!
This Is How The Universe Makes Blue Stragglers: The Stars That Shouldn’t Exist
“New stars form in large clusters, creating stars of all different masses simultaneously.
As they age, the more massive stars die first, leaving only the lower-mass ones behind.
We can date star clusters by examining which stars remain when we plot out stellar color vs. temperature. The older a cluster is, the redder, lower-mass, and less bright its surviving stars are. Globular star clusters are the oldest; some haven’t formed stars in ~13 billion years. Yet if we look closely inside these ancient relics from the young Universe, we’ll find a few blue stars.”
Okay, science fans, I’ve got a mystery for you. When you look at a star cluster, you’ll find a wide variety of stars inside: from the ultra-massive, hot, blue ones down to the lower-mass, cool, red ones. The older a cluster is, the redder it is, because the more massive, hotter, bluer ones burn through their fuel faster and die first. But as a cluster gets redder, we’ll inevitably find a few blue stars that don’t belong. These “blue straggler” stars behave as though they’ve formed at a later time than the rest of the cluster, even though we know that cannot be true. Yet they’re real, they’re there, and their lifetimes are often just 10% the known age of the cluster itself.
Think you can solve the mystery? Come read the story and see if you’ve got it right!
Ask Ethan: How Do Massless Particles Experience Gravity?
“Given the equation for gravity between two masses, and the fact that photons are massless, how is it possible for a mass (like a star or a black hole) to exert influence on said photon?”
You know the law of universal gravitation: you put in what any two masses are, how far apart they are from each other, and the gravitational constant of the Universe, and you can immediately know what the force is between any two objects. Set one of the masses to zero, and the force goes to zero. So why is it, then, that if you take the ultimate particle with no mass, a photon, and pass it close by a mass, its path does bend? Why do massless particles experience gravity?
To understand why, you should think about what happens if you and I start at the same place near a mass, but I’m stationary and you’re moving. How far away is that mass? What’s the “r” that goes into Newton’s equation? And who’s right: me or you?
The answer is that we both need to be right, and Newton won’t get us there. Come get the real story on gravity, and learn why, in the end, massless particles feel it, too!