83719545
submission
StartsWithABang writes:
Over 100 years ago, Einstein shook up the physics world with a number of groundbreaking discoveries: special relativity, brownian motion, the photoelectric effect, and his most famous equation, E = mc^2. This mass-energy equivalence underlies everything from antimatter to atomic bombs to the process that powers the Sun. Yet our Universe didn't have to have this relation; energy could have been equal to any constant times mass times the speed of light squared. Yet if you demand that both energy and momentum are conserved in any interactions, that freedom goes away, and E = mc^2 becomes, once again, your only option.
83694115
submission
StartsWithABang writes:
Dark matter is one of the biggest mysteries in the Universe. We can feel its gravitation, we can see its effects on galaxies, clusters and the large-scale structure of the Universe. But when it comes to very small scales, we haven’t been able to detect dark matter, either directly or indirectly, leading us to wonder at what it’s mysterious nature might be. While the notion that primordial black holes could be the dark matter has been disfavored by a large suite of observations, the LIGO detection of two merging black holes – of a particular, unusual mass – has rekindled interest in that nearly-abandoned idea. Could the fluctuations in the cosmic infrared background actually be due to these primordial black holes, and could they make up 100% of the dark matter? Almost certainly not, and here's the reason(s) why.
83626157
submission
StartsWithABang writes:
One of the strangest, most novel predictions of Einstein's relativity is that mass would not only curve space, but that the curved space would act like a lens. Background light traveling past this mass would become magnified, distorted and stretched. In some cases, arc, multiple images or even perfect, 360 rings would occur. Although this gravitational lensing phenomenon was theoretically predicted shortly after it was proposed, it was only in 1937 that Fritz Zwicky realized that a galaxy cluster could cause this phenomenon. 42 years later, 1979's discovery of the Twin QSO validated this picture, and hundreds of other instances of lensing have been found since.
83587485
submission
StartsWithABang writes:
Perhaps the most fundamental difference between day and night is the difference between light and dark that our eyes perceive. While everything is illuminated during the day, the night sky is completely dark, with the sole exception of the stars, galaxies and objects reflecting sunlight back at our world. You might intuit that this is simply because we can’t gather enough light to see the most distant objects in the Universe, but even if we gather arbitrarily large amounts of light, there are still dark spaces between the galaxies, where no shining objects exist. Indeed, there’s a mathematical theorem that if the Universe were of infinite size and a uniform (even if small) density, every direction you looked would eventually end on a light source. The resolution lies in two sources: the Big Bang and the limitations of our vision’s wavelength perception.
83567843
submission
StartsWithABang writes:
Perhaps the greatest, most successful scientific theory of the past century is Einstein’s General Relativity, our theory of gravitation that has answered every challenge to it for the past 101 years with resounding success. Yet before that, Newton’s gravity did the same thing for more than twice as long! The culprit that finally brought the universal theory of ground was incredible in its simplicity: the orbit of the planet Mercury. Observations dating from the late 1500s of the planet Mercury’s position indicated a precession of its orbit of 5600 per century, while Newtonian gravity predicted 5557 per century. That less-than-1% difference proved significant, however, and it was Einstein’s General Relativity that eventually made all the difference.
83492617
submission
StartsWithABang writes:
The vast majority of elements beyond hydrogen found on Earth were created inside a massive star and blown back into the interstellar medium in a catastrophic supernova explosion. In a certain way, everything you’ve ever held in your hand – including another person’s hand – is you holding a dead star. But thanks to the Chandra X-ray Observatory and more than 13 years of observations of an expanding, young supernova remnant, we’re able to construct a true 3D model of one of the galaxy’s youngest dead stars. Thanks to 3D printing, you can now literally hold a dead star in your hand.
83466327
submission
StartsWithABang writes:
On Earth, category 5 hurricanes cause devastation wherever they make landfall, bringing sustained winds, rain, destruction and — in many cases — casualties. But despite how strong and massive these storms can be, they're just peanuts compared to what happens on our Solar System's gas giants. While Saturn's north pole and Jupiter's great red spot are powerful, sustained storms that are far larger than anything found on our world, a world-encircling storm on Saturn that raged for over 200 days from 2010-2011 broke all the records. At its grandest, it was large enough to contain 10-to-12 Earths.
83431411
submission
StartsWithABang writes:
Inside a typical human body, beneath the organs, cells and even molecules that define us, there are atoms: some 7 × 10^27 of them in each of us. Mostly oxygen, carbon, hydrogen and nitrogen (with less than 1% of everything else combined), this tremendous number leads to an intriguing possibility: that at any given moment in your life, some of those atoms were once inside any historical living being you choose.
While the atoms you obtain through ingesting food might be incredibly well segregated depending on where you are, the atoms from Earth’s liquids or atmosphere are very well mixed, meaning that there are hundreds of billions of atoms inside of you from King Tut, trillions from Sue the T-Rex and even an atom or two in your lungs from Caesar’s last breath.
83413985
submission
StartsWithABang writes:
Back in the 1990s, scientists were quite surprised to find that when they measured the brightness and redshifts of distant supernovae, they appeared fainter than one would expect, leading us to conclude that the Universe was expanding at an accelerating rate to push them farther away. But a 2015 study put forth a possibility that many scientists dreaded: that perhaps these distant supernovae were intrinsically different from the ones we had observed nearby. Would that potentially eliminate the need for dark energy altogether? Or would it simply change ever-so-slightly the amount and properties of dark energy we required to explain modern cosmology? A full analysis shows that dark energy is here to stay, regardless of the supernova data.
83311497
submission
StartsWithABang writes:
To gaze into the empty abyss of deep space with the most expensive telescope of all requires a great leap of faith: that you’ll find something worth observing when you look. In 1995, the Hubble Space Telescope photographed the same regions of space 342 times, unveiling thousands of undiscovered galaxies. More than 20 years later, we’ve used this same technique to determine that the observable Universe has at least 170 billion galaxies spread throughout it. The James Webb Space Telescope is poised to unveil even more, with the capability of seeing back to when the Universe was less than 2% of its current age.
83276653
submission
StartsWithABang writes:
When it comes to normal matter, dark matter is a bit of a puzzle. Other than through the gravitational force, there’s no way we’ve yet figured out to make it interact. Try and collide it with matter and it passes right through; try and bombard it with energetic particles or radiation and it’s completely transparent. But the story is quite different when it comes to dark matter and black holes. While it won’t make an accretion disk or “funnel” into the black hole, once it crosses the event horizon, it inevitably hurls towards the singularity, adding to the mass and angular momentum of the black hole. But beyond that, there’s no way to know what went into your black hole, as what comes back out in the form of Hawking radiation will have no memory of how much dark matter vs. how much normal matter went into your black hole to begin with.
83261277
submission
StartsWithABang writes:
When it comes to many issues, democracy and popular opinion does and should determine the outcome. But when it comes to science and scientific issues, popular opinion or the votes of even an elite group of people doesn't mean very much at all. Instead, it's the truth that the Universe tells us about itself, through experiment, measurement and inquiry, that determines the answer. We may act like climate change, nuclear power, GMOs, fluoridated drinking water and a whole host of other issues are determined by science, but for the vast majority of us, it's our opinions and ideologies that determine our stances on these issues, not the science itself. This is a problem that's plagued all of science, even astronomy, going back for generations to the original 'Great Debate,' which solved absolutely nothing.
83160569
submission
StartsWithABang writes:
When fine-and-coarse-grained sand is carried by the winds across uneven terrain, sand dunes form here on Earth. But on Mars, where the atmosphere is only 0.7% what it is here, the sand is made of different composition and the winds gust to up to 60 mph (100 kph), do sand dunes behave the same way? The Mars Curiosity rover intends to find out! By observing grain flow, ripples, grain fall and more, and by going into the dunes themselves and scooping them into its analysis devices, we hope to uncover our first understanding of active sand dunes on another planet.
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.
83109395
submission
StartsWithABang writes:
When it comes to the Universe, there are some dead giveaways as to what its age is. Its elemental composition changes, the types of stars that are present evolve, the large-scale structure visible to us morphs, grows and ceases, and the temperature of the cosmic microwave background drops, among many other signs. Yet when we put them all together, there are only two methods available to measure the age of the Universe: the measurement of its expansion history and the measurement of the age of the oldest stars. The first is by far the more accurate, at 13.81 billion years (plus or minus just 120 million), while the second validates that picture, with a maximum age of 13-to-14 billion years.
