Yesterday I wrote about the lack of evidence for extraterrestrial intelligence. While there are lots of possible reasons why such evidence isn’t forthcoming, the seeming abundance of potentially habitable worlds in the cosmos seems to raise an interesting paradox. It is often known as the Fermi paradox, and can be basically stated as a question. Given the high number of potentially habitable worlds, and the apparent ease of life’s appearance on Earth, why haven’t we been contacted by alien civilizations? While there are lots of possible solutions to the paradox, one increasingly popular idea is known as the great filter. Read more
One of the big unanswered questions in astronomy is whether there are other intelligent civilizations in the universe. There have been searches for signals from alien civilizations, as well as messages we’ve sent into space in hopes that other civilizations can detect them. While there have been a few odd signals that some have speculated might be due to intelligent aliens, there’s been no clear evidence of extraterrestrial intelligence. At the same time, there is lots of evidence that potentially habitable planets exist. By some estimates there could be 8 – 20 billion Earth-like planets in our galaxy alone. So why has there been no signal from them? Read more
Suppose you measure the time a planet takes to orbit the Sun (its period), and compare it with a measure of its distance from the Sun (the semi-major axis). If you plot the logarithm of periods for all the planets (and even Pluto) vs the logarithm of their semi-major axes, you find they all lie along a line with a slope of 3/2. If you do the same for the moons of Jupiter, or Saturn, you get the same slope. The same is true for asteroids, comets, exoplanets and binary stars. They all follow the same 3/2 relation, and fall along the same line so long as they’re orbiting the same body.
3D animation is captivating, and so are semi-realistic dolls and robots that almost look like people. As these things get more lifelike, there is a point where they stop looking cuddly, and start looking creepy. In pop culture, this is called the uncanny valley. Today we’re going to talk about this with Dr. Grant Gutheil, Associate Professor of Psychology at Nazareth College in Rochester NY. In the second half of our show we’ll talk about what all the fuss is regarding a black hole in the center of our galaxy.
Host: Brian Koberlein
Guest: Grant Gutheil
Producer: Mark Gillespie
Music: Marcus Warner
The One Universe at a Time Podcast is produced at the Rochester Institute of Technology with support from the RIT College of Science.
In general relativity a black hole is a relatively simple object. It can be described by three basic quantities: its mass, its rotation (angular momentum), and its charge. No matter what type of material collapses into a black hole, in the end it’s reduced to mass, rotation and net charge. This property is known as the no-hair theorem, because unlike other astronomical objects like stars and planets, black holes should have no features (hair). But is the theorem too simplistic? Read more
Dark matter remains enigmatic, but we are learning more about it. While much of the observations about dark matter have determined what it’s not, there hasn’t been nearly as much data to determine what it is. So far we know that it is predominantly cold (meaning it isn’t zipping around at near light speeds) and it likely interacts with matter through the weak force and gravity. It’s generally been thought that dark matter should also be self-interacting, but recent observations haven’t shown any such interaction. But new observations of the galaxy cluster Abell 3827 show some evidence of dark matter’s self-interaction. Read more
Yesterday I talked about the CMB cold spot, and how it could be due to a lack of galaxies between us and the cosmic background. That’s because when galaxies are in the way of our view they can make the cosmic microwave background appear warmer than it actually is. On the face of it, that seems counter-intuitive. How can blocking some of the cosmic light make it appear warmer? It all has to do with the Sachs-Wolfe effect, or more specifically the integrated Sachs-Wolfe effect. Read more
The cosmic microwave background is an extraordinarily bit of observational data. It not only confirms details about the big bang, it also tells us things about the structure of the universe as a whole. One of the striking features of the CMB is how remarkably uniform it is. There are slight variations in the temperature of the CMB at different points in the sky, but this is exactly what standard cosmology predicts. But there is one patch of the cosmic background that’s a bit unusual, and it’s known as the CMB cold spot. Read more
When we observe galaxies across the universe, we find that most of them have supermassive black holes in their centers. Our own Milky Way galaxy, for example, has a black hole of about 4 million solar masses. This connection between black holes and galaxies raises an interesting question regarding the origin and evolution of galaxies. Did early galaxies form around black holes, or did black holes form within young galaxies? In other words, which came first, the black holes or the galaxies? Read more