83128777
submission
StartsWithABang writes:
If you were to send a space probe to a distant star system, gather information about it and send it back to Earth, you'd have to wait years for the information to arrive. But if you have an entangled quantum system — say, two photons, one with spin +1 and one with spin -1 — you could know the spin of the distant one instantly by measuring the spin of the one in your possession. Are there prospects, then, for entangling quantum particles, placing one aboard a spacecraft and sending it to a distant star, making a measurement at that distant location and then making a measurement here to know what you saw over there? It's an incredible idea to exploit quantum weirdness. While the laws of physics allow you to indeed know the properties of the other member of the pair by making a measurement here, they conspire to prevent you from transmitting information faster-than-light.
81589367
submission
StartsWithABang writes:
The need for a February 29th, once every four years or so, doesn’t just give us an extra day this year, but it keeps the calendar from drifting and failing to align with the seasons. Even so, the scheme we have worked out today — where years divisible by 4 but not those divisible by 100 unless also divisible by 400 get an extra day — isn’t perfect, and will get worse as time goes on. The current misalignment between our calendar and the actual Earth’s orbit is big enough that we’ll be off by a day every 3,200 years, but bigger news is that the Earth’s rotation rate is changing, as our day lengthens and our spin slows down. In another 4 million years, we won’t need leap days at all, and if we extrapolate backwards, we can find that early Earth had a day that lasted just 6.5 hours.
81048029
submission
StartsWithABang writes:
When we look out into the Universe, we normally gain information about it by gathering light of various wavelengths. However, there are other possibilities for astronomy, including by looking for the neutrinos emitted by astrophysical sources — first detected in the supernova explosion of 1987 — and in the gravitational waves emitted by accelerating masses. These ripples in the fabric of space were theorized back in the early days of Einstein’s General Relativity, and experiments to detect them have been ongoing since the 1960s. However, in September of 2015, Advanced LIGO came online, and it was the first gravitational wave observatory that was expected to detect a real gravitational wave signal. The press conference on Thursday is where the collaboration will make their official announcement, and in the meantime, here’s an explainer of what gravitational waves are, what Advanced LIGO can teach us, and how.
80948841
submission
StartsWithABang writes:
If you want to see farther, deeper and at higher resolution than ever before into the Universe, you need four things: the largest aperture possible, the best-quality optical systems and cameras/CCDs, the least interference from the atmosphere, and the analytical techniques and power to make the most of every photon. While the last three have improved tremendously over the past 25 years, telescope size hasn’t increased at all. That’s all about to change over the next decade, as three telescopes — the Giant Magellan Telescope, the Thirty Meter Telescope and the European Extremely Large Telescope — are set to take us from 8-10 meter class astronomy to 25-40 meter class. While the latter two are fighting over funding, construction rights and other political concerns, the Giant Magellan Telescope is already under construction, and is poised to be the first in line to begin the future of ground-based astronomy.
80366171
submission
StartsWithABang writes:
As we peel back the layers of information deeper and deeper into the Universe’s history, we uncover progressively more knowledge about how everything we know today came to be. The discovery of distant galaxies and their redshifts led to expanding Universe, which led to the Big Bang and the discovery of very early phases like the cosmic microwave background and big bang nucleosynthesis. But before that, there was a period of cosmic inflation that left its mark on the Universe. What came before inflation, then? Did it always exist? Did it have a beginning? Or did it mark the rebirth of a cosmic cycle? Maddeningly, this information may forever be inaccessible to us, as the nature of inflation wipes all this information clean from our visible Universe.
80321721
submission
StartsWithABang writes:
Geoff Marcy. Tim Slater. Christian Ott. And a great many more who are just waiting to be publicly exposed for what they've done (and in many cases, are still doing). Does it mean that astronomy has a harassment problem? Of course it does, but that's not the real story. The real story is that, for the first time, an entire academic field is recognizing a widespread problem, taking steps to change its policies, and is beginning to support the victims, rather than the senior, more famous, more prestigious perpetrators. Astronomy is the just start; hopefully physics, computer science, engineering, philosophy and economics are next.
80147447
submission
StartsWithABang writes:
The news has been aflame with reports that North Korea detonated a hydrogen bomb on January 6th, greatly expanding its nuclear capabilities with their fourth nuclear test and the potential to carry out a devastating strike against either South Korea or, if they’re more ambitious, the United States. The physics of what a nuclear explosion actually does and how that signal propagates through the air, oceans and ground, however, can tell us whether this was truly a nuclear detonation at all, and if so, whether it was fusion or fission. From all the data we’ve collected, this appears to be nothing new: just a run-of-the-mill fission bomb, with the rest being a sensationalized claim.
80125141
submission
StartsWithABang writes:
With the launch of the Fermi satellite in the late 2000s, we began observing the highest energy photons in the Universe — gamma rays — all over the sky, to unprecedented precision. Produced from cosmic ray showers in space when high energy protons run into other, stationary protons, these gamma rays locate point sources from supermassive black holes to supernova remnants to pulsars. There is, additionally, a great correlation between the infrared sky and the gamma ray sky, since the great high-energy background scatters off of the diffuse infrared gas, producing gamma rays there as well. But while a great many sources can be correlated with known structures, Fermi reveals at least one unknown, intense behemoth that emits spectacularly in gamma rays.
80017677
submission
StartsWithABang writes:
In 2012, astronomers announced that the nearest star system to us, the Alpha Centauri system, possessed at least one exoplanet around it. A periodic signal that recurred just every 3.24 days was consistent with an Earth-sized exoplanet orbiting and gravitationally tugging on the second largest member of the star system: Alpha Centauri B. That planet, named Alpha Centauri Bb, turns out not to actually be there. A reanalysis of the data shows that a combination of stellar properties and the times at which the observations were made conspired to produce this spurious signal: a signal that goes away if the data is handled correctly. Accounting for everything correctly reveals something else of interest, a periodic 20-day signal, which may turn out — with better observations — to be Alpha Centauri’s first exoplanet after all.
79752489
submission
StartsWithABang writes:
Looking out at the distant stars, galaxies and radiation in the Universe today, we’ve been able to determine not only what it’s made out of, but how long it’s been since the Big Bang: 13.8 billion years. Put all that information together, and you can also figure out how large the observable part of that Universe is today. From our point of view, it appears to extend for 46.1 billion light years in all directions. So what if you extrapolate backwards, to the very end of inflation and the start of the hot, dense state we identify with the Big Bang, and ask how large that 46.1 billion light year “size” was back then? How big would it be? Depending on the particulars of when inflation came to an end, the answer is somewhere between the size of a soccer ball and the size of a city block, no smaller and no larger.
79706375
submission
StartsWithABang writes:
They say that one of the most exciting phrases to hear in science is not "eureka!" but "that's funny," and the Apollo 17 astronauts, just over 43 years ago, certainly got such a moment when they discovered orange soil just beneath the grey regiolith. What turned out to be volcanic glass with tin inclusions had another surprise: olivine deposits that showed signs that they contained significant amounts of water inclusions when they were baked, at about ~1200 parts-per-million. This matches the water levels in Earth's upper mantle along ocean ridges, providing further evidence for the giant impact hypothesis and a common origin for the Earth and Moon.
79683661
submission
StartsWithABang writes:
Earlier this month, a conference was held devoted to the question of whether untestable scientific ideas like string theory and the multiverse are actually science or not. While many opinions were stated and no one changed their mind, the answer is apparent: unless you're willing to change the definition of science to include 'this thing that isn't science,' then no, string theory is not science. It's a theory in the sense of a mathematical theory — like set theory, group theory or number theory — but it isn't yet a scientific theory. Of course, it could become science, but that would require that it actually do the things a scientific theory does: make testable predictions that can be validated or falsified.
79444887
submission
StartsWithABang writes:
Many of us dream of becoming astronauts as a child, but give up on that dream for a number of reasons — the seemingly impossible odds, the demands of daily life, the rigors of preparation — and never even apply. But for a great many, that dream remains alive; the last time NASA had open applications, over 6,000 people threw their hat in the ring, with eight selected. Yesterday, NASA once again opened up astronaut applications, and one prospective applicant has written a manifesto about lessons learned in becoming an aspiring astronaut. While not all of us have the desire to strap ourselves to a rocket and orbit in a tin can above Earth, we all have something to learn from this perspective.
79351691
submission
StartsWithABang writes:
When you take a look at a spiral galaxy in the night sky, it seems obvious that the stars on the inner parts of the galaxy are going to orbit in less time than the stars in the outer part. This turns out to be true, something we've figured out even though the timescales for galaxies to complete a full revolution are far longer than we've ever been able to observe. But one thing that doesn't happen is that the arms don't "wind up," meaning that the galaxies don't see the spiral patterns intensify as they age. Even though we first observed spiral structure in galaxies back in the mid-1800s, we didn't understand what the cause of this effect was for over 100 years. Yet now, not only do we understand it, but we can explain why galaxies will never wind up over time, and how this effect is true with or without dark matter.
79327349
submission
StartsWithABang writes:
If you calculate the forces between two fundamental particles separated by subatomic distances, you find that the strong, electromagnetic or weak nuclear force could all be the strongest, dependent on the particulars of your setup. But throw gravity in there, and it turns out to be weaker by some 40 orders of magnitude. This discrepancy, that gravity is such an oddball, is known as the hierarchy problem, and is by many measures the greatest unsolved problem in theoretical physics. Yet the new, upgraded run of the LHC has the potential to uncover any one of four possible solutions, some of which we have hints for already.
