Q & A
esiegel | December 10, 2015“Did you ever read my words, or did you merely finger through them for quotations which you thought might valuably support an already conceived idea concerning some old and distorted connection between us?” -Audre Lorde
One of the most damning, albeit accurate, condemnations of String Theory that has been leveled at it is that it's untestable, non-empirical, and offers no concrete predictions or methods of falsification. Yet some have attempted to address this failing not by coming up with concrete predictions or falsifiable tests, but by redefining what is meant by theory confirmation.…
esiegel | December 27, 2013"Never waste your time trying to explain who you are to people who are committed to misunderstanding you." -Dream Hampton
Perhaps no word in the English language generates as much misunderstanding as the word theory. In scientific circles, this word has a very specific meaning that's different from everyday use, and -- as a theoretical astrophysicist myself -- I feel it's my duty to help explain exactly what we mean when we use it. In this week’s Ask Ethan column, I'm pleased to pull out of our question/suggestion box the question of Ripley, who asks:
I often see that because there is no "100…
esiegel | November 9, 2013"One of the most tragic things I know about human nature is that all of us tend to put off living. We are all dreaming of some magical rose garden over the horizon instead of enjoying the roses that are blooming outside our windows today." -Dale Carnegie
Our new Ask Ethan segment has been really popular, and the questions and suggestions keep pouring in. It's your Universe too, and if there's something you want to know about it, you should ask! (So keep it up!) This week's question is one of the biggest of them all, and it comes courtesy of John L. Ferri, who asks,
I have a difficult time…
esiegel | September 6, 2013"Education is an admirable thing, but it is well to remember from time to time that nothing worth knowing can be taught." -Oscar Wilde
As many of you know, last weekend I launched a suggestion box here on the site, and I've been overwhelmed by the response: about fifty of you have sent something in to me in the first less-than-a-week of this alone!
Image credit: Thao Nelson of http://mycredo.wordpress.com/.
So, let's start answering them! There are more than enough excellent questions and suggestions to keep me busy for a long time, but with the new academic year starting up, one of them…
esiegel | May 10, 2013"As seismologists gained more experience from earthquake records, it became obvious that the problem could not be reduced to a single peak acceleration. In fact, a full frequency of vibrations occurs." -Charles Francis Richter
You've all been around long enough to be familiar with the severe damage that earthquakes can cause, rattling and cracking the ground, shaking down buildings, and creating catastrophic tsunamis tidal waves. In short, the largest ones that occur in the wrong places will cause billions of dollars worth of damage and will kill thousands of people.
Image credit: AP / Press…
esiegel | March 19, 2013"A lot of mothers will do anything for their children, except let them be themselves." -Banksy
One of the great joys I got to experience came last year, when for the very first time, I was invited to be a guest of honor at a most fabulous convention: MidSouthCon 30!
Image credit: MidSouthCon XXX, originally from http://www.midsouthcon.org/.
I went into it not knowing what to expect, and I wound up having one of the best times I could have asked for. I met some of the kindest, most interesting people I've ever met in my life, and I felt like everyone there immediately accepted me into their…
esiegel | March 15, 2013"If you're a reporter, the easiest thing in the world is to get a story. The hardest thing is to verify. The old sins were about getting something wrong, that was a cardinal sin. The new sin is to be boring." -David Halberstam
It was only a few months ago that both collaborations at the Large Hadron Collider in CERN -- CMS and ATLAS -- announced the discovery of a new particle at about 125-126 GeV of energy: something that looked an awful lot like what the Standard Model predicted the Higgs Boson should be.
Image credit: the CMS detector at CERN, 2009.
This was the result of decades of…
esiegel | February 15, 2013“Don't wake me for the end of the world unless it has very good special effects.” -Roger Zelazny
It's always the ones you least expect that get you the worst, it seems. I went to bed last night excited that Asteroid 2012 DA14, a 200,000 ton asteroid, was going to pass within just 28,000 km (or 17,000 miles) of Earth's surface, which would make it the closest pass of an asteroid that large that we've ever observed.
Image credit: NASA / JPL Near-Earth Object Program Office.
I thought that would be the best way to celebrate today, which would be Galileo's 449th birthday. After all, it was…
esiegel | February 6, 2013"According to the special theory of relativity nothing can travel faster than light, so that if light cannot escape, nothing else can either. The result would be a black hole: a region of space-time from which it is not possible to escape to infinity." -Stephen Hawking
You may have encountered objects that are the same size as one another, but have very different masses.
Image credit: Basic Science Supplies / © Accelerate Media.
This is because they're made out of different elements. The higher you go in the periodic table, the larger and more massive your individual atoms are, and so…
esiegel | January 5, 2013"Stuff your eyes with wonder, live as if you'd drop dead in ten seconds. See the world. It's more fantastic than any dream made or paid for in factories." -Ray Bradbury
It wasn't all that long ago -- back when I was a boy -- that the only planets we knew of were the ones in our own Solar System. The rocky planets, our four gas giants, and the moons, asteroids, comets, and kuiper belt objects (which was only Pluto and Charon at the time) were all that we knew of.
Image credit: NASA's Solar System Exploration, http://solarsystem.nasa.gov/planets/index.cfm.
But these were just the worlds…
esiegel | January 2, 2013"Everyone carries a piece of the puzzle. Nobody comes into your life by mere coincidence. Trust your instincts. Do the unexpected. Find the others." -Timothy Leary
Here we are, on planet Earth, the product of generations of civilization-building, maybe four-billion years of evolution on our world, around 13.7 billion years into the existence of our observable Universe.
Image credit: Paranal Observatory, ESO / Babak Tafreshi.
The Universe, quite possibly, didn't have to be exactly the way it is. It didn't have to have the laws of physics be exactly what they are, with the masses and charges…
esiegel | December 14, 2012"And in the end
The love you take
Is equal to the love you make." -Paul McCartney
Every once in a while, I throw the chance out there (on facebook, twitter, or google+) to ask me whatever questions you want. Yesterday, for some insane reason, I invited people across all three platforms to ask me whatever they liked, with a dual promise that I'd not only answer them, but that the best ones would receive a free "The Year In Space" calendar for 2013, courtesy of the Planetary Society.
Image credit: The Planetary Society.
So I got a ton of questions, and now I'll do my best to answer them as…
esiegel | November 28, 2012"Summer ends, and Autumn comes, and he who would have it otherwise would have high tide always and a full moon every night." -Hal Borland
Of course you know the danger that would befall us if the Earth ever got too close to the Sun, as the Perry Bible Fellowship shows, atop. But have you ever stopped to think about the Moon in our skies, and what would happen if the Earth and Moon were closer together than they actually are?
Image credit: NASA / Galileo mission.
While photos such as this -- from the Galileo spacecraft -- accurately show the relative size and illumination of the Earth and…
esiegel | October 24, 2012"The sun is a mass of incandescent gas
A gigantic nuclear furnace
Where hydrogen is built into helium
At a temperature of millions of degrees" -They Might Be Giants
It's so ingrained in us that the Sun is a nuclear furnace powered by hydrogen atoms fusing into heavier elements that it's difficult to remember that, just 100 years ago, we didn't even know what the Sun was made out of!
Image credit: Landscape Photography by Barney Delaney.
The conventional wisdom at the time, believe it or not, was that the Sun was made out of pretty much the same elements that the Earth is! Although that…
esiegel | October 20, 2012"I spent every night until four in the morning on my dissertation, until I came to the point when I could not write another word, not even the next letter. I went to bed. Eight o'clock the next morning I was up writing again." -Abraham Pais, physicist
You've been in graduate school for many years now, and you've come a long way. You've completed all of your coursework, formed your Ph.D. thesis committee, passed your preliminary/oral/qualifying examinations, and have done an awful lot of research along the way. There's a glimmer of hope in your heart that maybe -- just maybe -- this will be…
esiegel | October 15, 2012“The aim of science is not to open the door to infinite wisdom, but to set a limit to infinite error.” -Bertolt Brecht
One of the most frequent questions I get about the Universe -- as a cosmologist -- isn't quite about the Big Bang in and of itself.
The expansion of the Universe in reverse; image source unknown.
The Big Bang is a remarkable idea, of course, that says that, based on the observations that the Universe is expanding and cooling today, it was hotter, denser, and physically smaller in the past. This gets particularly exciting when we extrapolate very far back in the history of…
esiegel | August 14, 2012"The colors of a rainbow so pretty in the sky.
Are also on the faces of people going by." -Louis Armstrong
It's no secret that white light is the light that we see when all the colors shine together and are seen at once. This has been known for over 400 years, when Isaac Newton demonstrated that white light could be broken up into all the known colors by dispersing it through a prism.
Image credit: Adam Hart-Davis.
All that we're doing is breaking white light -- in this case, sunlight -- up into all of its component colors. This can be done artificially (such as by configuring a prism) or…
esiegel | July 30, 2012"Black holes, which have no memory, are said to contain the earliest memories of the universe, and the most recent, too, while at the same time obliterating all memory by obliterating all its embodiments. Such paradoxes characterize these strange galactic monsters, for whom creation is destruction, death life, chaos order." -Robert Coover
Our Milky Way, the swath of light and dark that dominates the darkest skies here on Earth, contains a huge variety of stars: large and small, red and blue, from young to old to ancient.
Image credit: ESO / Serge Brunier, Frederic Tapissier, The World At…
esiegel | July 26, 2012"Nothing exists except atoms and empty space; everything else is just opinion." -Democritus of Abdera
When you take a look out at the Universe, past the objects in our own solar system, beyond the stars, dust and nebulae within our own galaxy, and out into the void of intergalactic space, what is it that you see?
Image credit: BRI composite-image of the FORS Deep Field, ESO, VLT.
What we normally think of as the entire Universe, consisting of hundreds of billions of galaxies, with about 8,700 identified in the tiny patch of deep-sky shown above. Each one of those galaxies, itself, contains…
esiegel | July 4, 2012"This is evidently a discovery of a new particle. If anybody claims otherwise you can tell them they have lost connection with reality." -Tommaso Dorigo
You've probably heard the news by now: the Higgs boson -- the last undiscovered fundamental particle of nature -- has been found.
The fundamental types of particles in the Universe, now complete.
Indeed the news reports just keep rolling in; this is easily the discovery of the century for physics, so far. I'm not here to recap the scientific discovery itself; I wrote what to expect yesterday, and that prediction was pretty much exactly what…