72086807
submission
StartsWithABang writes:
The overwhelming scientific conclusion based on the observable evidence is that the Universe is expanding and cooling, having emerged from a hot, dense state in the past. We can extrapolate back to a time before neutral atoms existed, before even nuclei could form, and if we continue the extrapolation all the way back, we arrive at a singularity. Only, that last step isn't necessarily one we can take, and the insistence of many on its existence may be the biggest mistake ever made about the Big Bang.
72084227
submission
StartsWithABang writes:
The Universe is filled with a wide variety of stars, planets, galaxies and other optical phenomenon. Despite the fact that there are no such things as green stars, on rare occasions, galaxies themselves appear to be emitting isolated green wisps into intergalactic space. Since the first such object was discovered eight years ago, this was a hotly debated mystery, one that’s been solved with an unlikely phenomenon: the atomic transitions of ionized oxygen, or the same physics that underlies the aurorae here on Earth!
72053981
submission
StartsWithABang writes:
You’re used to real numbers: that is, numbers that can be expressed as a decimal, even if it’s an arbitrarily long, non-repeating decimal. There are also complex numbers, which are numbers that have a real part and also an imaginary part. The imaginary part is just like the real part, but is also multiplied by i, or the square root of -1. It's a simple definition: the Mandelbrot set consists of every possible complex number, n, where the sequence n, n^2 + n, (n^2 + n)^2 + n, etc.—where each new term is the prior term, squared, plus n—does not go to either positive or negative infinity. The scale of zoom visualizations now goes well past the limits of the observable Universe, with no signs of loss of complexity at all.
71988793
submission
StartsWithABang writes:
Before there were planets, galaxies, or even stars in the Universe, there really was light. We see that light, left over today, in the form of the Cosmic Microwave Background, or the remnant glow from the Big Bang. But these photons outnumber the matter in our Universe by more than a-billion-to-one, and are the most numerous thing around. So where did they first come from? Science has the answer.
71948849
submission
StartsWithABang writes:
It’s pretty obvious that the Universe exists in such a way that it admits the possibility of intelligent life arising. After all, we’re here, we’re intelligent life, and we’re in this Universe. So at minimum, the Universe must exist in such a way that it’s physically possible for us to have arisen. But are there physically interesting things we can learn about the Universe from this line of reasoning alone? As it turns out, the answer is yes, but the things we can learn are extremely limited both in terms of scientific and philosophical significance.
71934399
submission
StartsWithABang writes:
If you take two clusters, groups, or individual galaxies and collide them together, you'd expect the stars to pass through unperturbed, the gas to experience friction, slowing down and heating up, while the dark matter, if it's truly collisionless, will do the same thing as the stars. But if there's a tiny frictional force at work on dark matter, it, too, will slow down a little bit. A team looking at 72 groups and clusters saw no effect of slowing down, but then on the 73rd one, they saw a separation between the mass reconstruction and the stars. Is this the first sign of dark matter's interactions, or is it simply an astrophysical effect, or maybe even a fluke? A good recap and rundown of what we're looking at to the best of our knowledge.
71908081
submission
StartsWithABang writes:
When it comes to measuring the expansion history of the Universe, the concept is simple enough: take something you know about an object, like a mass, a size, or a brightness, then measure what the mass, size or brightness appears to be, and suddenly, you know how far away that object has to be. Add in a measurement of the object’s redshift, and you can figure out not only what the expansion rate of the Universe is today, you can figure out the entire expansion history, and therefore what makes the Universe up. For practically all of the 20th century, we used brightness — or standard candles — exclusively. But new developments in both galactic surveys (like SDSS) and our understanding of dark matter and inflation has enabled us to use a new technique: baryon acoustic oscillations, or a standard ruler, which now gives us the best constraints ever on what dark energy is.
71872735
submission
StartsWithABang writes:
You've heard the saying, "God does not play dice with the Universe," and quite likely, of Schrödinger's cat as well. The idea that the Universe is random and — in many ways — unpredictable and indeterministic, is unsettling, to say the least. Yet it seems to be a fact inherent to our quantum Universe, a fact that neither Einstein nor Schrödinger could ever accept. Paul Halpern dives in deep to these issues in his newest book, as astrophysicist Ethan Siegel dishes in his review.
71833437
submission
StartsWithABang writes:
Of course the closest galaxies to us are going to be the brightest, with Andromeda, the Magellanic Clouds and the Triangulum Galaxy all visible to the naked eye. But beyond our local group? The next brightest galaxy is an oddity: 29 million light-years away, half the diameter of our Milky Way, and containing properties of both spiral and elliptical galaxies. In unparalleled views, come take a look at the sombrero galaxy, and learn what makes it so phenomenal.
71784299
submission
StartsWithABang writes:
The accelerated expansion of the Universe — and hence, dark energy — was discovered by taking the well-understood phenomenon of type Ia supernovae and measuring them out to great distances. The results indicated that they were fainter than expected, and hence more distant, and hence the Universe's expansion must be accelerating. But new results have just come out, showing that supernovae may not be standard after all. Does this mean dark energy may not be real, or that it may just be slightly weaker than we previously thought?
71755395
submission
StartsWithABang writes:
Earlier this week, NASA's chief scientist held a press conference, announcing that we should detect alien life by 2030, if both the Universe and the progression of telescope technology is as we expect. The technique is actually incredibly simple: examine what makes up the atmosphere of potentially inhabited exoplanets, and then you'll have your answer!
71735015
submission
StartsWithABang writes:
When we look at the centers of galaxies, it’s no surprise that there are large black holes there, millions or even billions of times the mass of the Sun. As we look farther and farther away, and hence farther back in time, we’d expect these masses to be much smaller. But what we find is that we have supermassive black holes at the centers of quasars many billions of times the Sun’s mass all the way back to when the Universe was just a few hundred million years old: less than 5% its current age. Does this mean our ideas about how the Universe formed all need to be thrown out? Hardly: here’s the solution to the mystery of how such massive black holes were formed so early on.
71722485
submission
StartsWithABang writes:
The Universe is absolutely fascinating as-is, and perhaps the most remarkable fact about it is that it can be understood, scientifically, at all. But all too often, the most popular pieces of information that get widely disseminated are complete misinformation. If you're at all interested in teaching or communicating science, there's only one rule you need to follow, and everything flows from that.
71702699
submission
StartsWithABang writes:
Last week, CERN's Large Hadron Collider restarted, poised to set the all-time collider energy record at 13 TeV. But how does it work, what is it attempting to find, and if there is new physics out there, how are we going to find out? In five easy steps, physicist Ethan Siegel walks us through exactly what's happening at the world's most powerful machine.
71620467
submission
StartsWithABang writes:
Of the solar eclipses where the Moon, Earth and Sun are perfectly aligned, about 50% of them are total, while the other half are annular. But this wasn't always the case, as the Moon has been spiraling out from Earth since it was first formed! As the Earth slows in its rotation, the Moon continues to move farther away to compensate. And about 650 million years from now, we'll experience our last total solar eclipse, and then we'll have to travel beyond Earth's surface to experience the phenomenon.
