84511857
submission
StartsWithABang writes:
One of the cardinal rules of a black hole is that anything that falls inside the event horizon – that crosses that invisible boundary – can never escape. That’s because the escape velocity from inside the event horizon is greater than the speed of light in a vacuum, c, a speed that nothing in this Universe can exceed. But in curved space, different observers don’t agree on what the speed of anything, even light, is at different locations in space. Some observers will even see a photon move at speeds greater than c, for that matter. Could that mean that maybe there’s a loophole, and that something like a passing gravitational wave could enable a particle or photon from inside the event horizon to make it out after all? It turns out that the answer is no, but the full explanation from General Relativity is more bizarre than anyone would have expected!
84491609
submission
StartsWithABang writes:
When gunpowder was first invented more than 1,000 years ago by mixing activated carbon (charcoal), sulfur and potassium nitrate together, its first major application was to the development of fireworks. By combining four simple elements – a launch, a fuse, a burst charge and ignitable stars – the most spectacular explosive shows could be produced. Yet the design of each stage only works with the proper understanding of the science behind it, and in particular, of the physics underlying it all. To get the right height, shape, size and color for your firework, you have to master each component of each stage. And yet, the science enables us to do exactly that!
84468029
submission
StartsWithABang writes:
The largest mountains, the greatest chasms, steepest cliffs and the tallest peaks on Earth are certainly impressive, particularly when compared to the scale of a human. But compared to the mountains on Mars, Io, Vesta or Iapetus, or the canyons and cliffs on Mars, Mercury, or even Charon, Earth’s features look puny. How could these small worlds, some of which – like Vesta – are barely 5% the diameter of Earth, have features that dwarf our own planet’s? The answer is in gravity itself: without the incredible gravitational pull that Earth experiences at its surface, these irregularities are unchecked by the same forces that pull Earth into such a nearly perfect sphere.
84444493
submission
StartsWithABang writes:
The second lightest and second most abundant element in the Universe, helium, is incredibly rare on Earth. Practically none of the helium that Earth was formed with still exists, since was too easy for it to escape from our tenuously held atmosphere, unlike the gas giant worlds. But deep underground, in the heavy-element-rich interiors of the Earth, new helium is continuously produced. The heaviest unstable elements, like thorium, uranium and radium, are particles that undergo alpha decay on timescales of hundreds of millions to billions of years. They give rise to massive pockets of helium, enabling us to extract it for scientific, medical and more frivolous purposes. But if we waste this cheap, abundant and easy-to-obtain material now, humanity doesn’t have hundreds of millions of years to wait for it to replenish itself.
84419863
submission
StartsWithABang writes:
At the end of its second, high-energy run, the Large Hadron Collider appeared to display evidence that perhaps a new particle existed at an energy of 750 GeV. The excess of twin photons produced at that energy appeared in both the ATLAS and CMS detectors, and might indicate the first particle beyond the standard model. It might also be a little-understood feature of the standard model itself, or — perhaps most likely — it may be merely statistical noise. But perhaps the 'nightmare scenario' of no new particles is exactly what physics needs, to divert us away from the dead ends of naturalness, elegance, unification and greater and greater symmetries, which have borne no experimental fruits in more than 40 years.
84394047
submission
StartsWithABang writes:
The combination of New Horizons and Hubble to work together allow us to create the longest-baseline parallax images of all time. Through this combination, we’ve managed to learn more about a distant, long-range Kuiper belt object – in this case, (15810) 1994 JR1 – than ever before. This technique will enable us, if we so choose, to identify, characterize and learn the orbits, rotational periods and even topography and color of dozens of worlds beyond Neptune, if only we choose to extend New Horizons’ mission beyond the end of this year.
84355801
submission
StartsWithABang writes:
Earlier this week, NASA announced the discovery of Asteroid 2016 HO3, calling it Earth’s second moon. And it turns out that this is an object in a stable orbit, the same distance from the Sun as the Earth, that can be found revolving around our world at a distance between 38 and 100 times the distance from us to the Moon. But that isn’t exactly the same as having a second Moon! In order to be considered not just a natural satellite but a stable one, you need to remain orbiting your parent world for a long period of time, not just tens, hundreds or thousands of years, like a transient quasi-satellite. Despite its current orbital characteristics, this object is much more akin to the multiple Trojan asteroids orbiting with our world than anything we’d consider moon-like.
84333555
submission
StartsWithABang writes:
There are certain words that simply get people’s hackles raised, shutting off the part of their brain that normally responds to reason and instead results in an emotional response taking over. For some, that word is “theory,” one of the words with the biggest gap between its colloquial and scientific uses. But another such term is “consensus.” You might have grown up — like many — believing that doing something yourself is the only way to ensure it gets done correctly. But when it comes to science, not only is that not the case at all, but a scientific consensus isn’t the conclusion, but rather the starting point.
84308125
submission
StartsWithABang writes:
If you had told an astrophysicist five years ago that binary black holes were common, that would’ve been news, but not surprising. If you had told them that ~30 solar masses was a good estimate for each one of their masses, though, you might have had to pick their jaws up off the floor. Yet LIGO’s very first detection showed us exactly that, much to the surprise of many. So how did these black holes come to be? After much numerical study, it appears that young, metal-poor stars about 40-100 solar masses each conspired to create these binary black hole pairs, with only one of the members resulting in a supernova. The rest is cosmic history.
84286139
submission
StartsWithABang writes:
Now that not just one but two gravitational wave events have been directly detected, we're officially in the era of true gravitational wave astronomy. LIGO has taught us something unique about stellar mass black holes, and will continue to teach us about these objects, their population statistics, and their merger rates as time goes on. But beyond that, we're poised to learn the origin of gamma-ray bursts, to observe neutron star quakes, and once we go to space, to observe supermassive black holes and possibly even the relic gravitational waves from cosmic inflation. The latter would do more than confirm what set up the Big Bang; it would prove that gravity is an inherently quantum force!
84266219
submission
StartsWithABang writes:
Given the huge number of stars, planets, and chances at life that the galaxy and the Universe has given us, it seems paradoxical that we haven’t yet encountered any form of alien intelligence or even life. The discoveries make in the field of exoplanet studies, particularly by the Kepler mission, make this an even bigger problem than we anticipated: more than 10^22 planets with Earth-like condition are expected to exist in our Universe. So does this mean that intelligent life beyond Earth is pretty much a certainty, as Adam Frank asserted in the New York Times last week? Hardly; what it means is that we have a long way to go in the sciences of astrobiology, abiogenesis and exo-evolution. There’s so much to learn that drawing conclusions about what’s out there is more than premature: it’s not even science.
84236767
submission
StartsWithABang writes:
When supermassive black holes have a large amount of matter fall onto them, they accelerate a large amount of the ionized material – particularly electrons – into high-velocity, bi-directional jets. In many cases, those jets of material collide with previously blown-off gaseous material and create high-energy X-rays. While these can often be visible across the cosmos, it’s very rare to have a jet so large. The galaxy Pictor A, imaged by Chandra over a 15 year timescale, has the longest known such jet at 300,000 light years, culminating in a “hot spot” shockwave, where the electrons collide with the gas at greater than the speed of sound. A counterjet, invisible with all other telescopes, was also found by Chandra.
84202095
submission
StartsWithABang writes:
Seen poking through a cloud, trees or other opaque materials, sunbeams are one of the most surprising natural phenomena, when you think about it. There’s always scattered, ambient sunlight in all directions, and the bright sunshine is never visible as a ray when there aren’t clouds. Moreover, the light almost always appears to diverge away from the beam’s point of origin, rather than seeming to be the parallel rays you’d expect. Yet a combination of the surrounding shadowed darkness, human perception, atmospheric scattering and the angle of the sunlight itself all conspire to create this one-of-a-kind optical phenomenon.
84181947
submission
StartsWithABang writes:
Making up some 85% of the mass in our Universe, dark matter is necessary to explain the motions of individual galaxies, the grouping and clustering of assemblies of galaxies, the large-scale structure of the Universe and more. But on a much closer-to-home level, dark matter may be absolutely essential to the origin of life, too! Without dark matter, supernova explosions and starburst events would still create copious amounts of heavy elements, driven outwards by winds and the force of the explosions. But it’s the extra gravity of the dark matter that prevents most of this material from escaping, and allows it to take part in the formation of future generations of stars, to participate in rocky planet formation, and to deliver the ingredients necessary for life.
84165269
submission
StartsWithABang writes:
When the first gravitational wave signal ever, GW150914, was directly detected, NASA’s Fermi GBM team shocked the world by announcing the detection of a high-energy burst of electromagnetic radiation. This was a huge surprise, because merging black holes shouldn’t have a bright gamma ray or X-ray flash associated with them! A statistical reanalysis and the ESA’s INTEGRAL satellite both failed to confirm it, but it would take a second event to know for certain. With GW151226 now in the books, a look through the Fermi GBM data shows what we suspected all along: black holes DON’T burst when they merge!
