gravity
esiegel | June 22, 2012"Some prophecies are self-fulfilling
But I've had to work for all of mine
Better times will come to me, God willing
Cause I can't leave this world behind" -Josh Ritter
You sure can't leave this world behind. At least, not very easily. The reason for it, of course, is gravity.
Image Credit: Physclips, via the University of New South Wales' School of Physics.
Here on the surface of the Earth, the gravitational potential well is pretty large; large enough that there's no easy way off. Sure, you can pour a huge amount of energy into a rocket to try and overcome this gravitational potential…
esiegel | May 10, 2012"They say 'A flat ocean is an ocean of trouble. And an ocean of waves... can also be trouble.' So, it's like, that balance. You know, it's that great Oriental way of thinking, you know, they think they've tricked you, and then, they have." -Nigel Tufnel
Black holes* are some of the most perplexing objects in the entire Universe. Objects so dense, where gravitation is so strong, that nothing, not even light, can escape from it.
Image credit: Artist's Impression from MIT.
But there are a number of very counterintuitive things that happen as you get near a black hole's event horizon, and a…
esiegel | May 8, 2012"There's nothing that cleanses your soul like getting the hell kicked out of you."
-Woody Hayes
There's no doubt that we lucked out when it came to the formation of our Solar System.
Image credit: Michael Pidwirny, retrieved from cosmosportal.org.
Our inner Solar System, where temperatures are ideal for liquid water and life-as-we-know-it, is full of rocky planets and devoid of any gas giants for many hundreds of millions of miles. But, as we know all too well from the last twenty years of finding exoplanets, this isn't the only way it could have turned out.
In fact, of the some 2,300…
esiegel | May 2, 2012"This is the way I wanna die. Torn apart by angry fans who want me to play a different song." -Regina Spektor
You're familiar with the classic picture of a black hole: a dark, dense region at the center from which no light can escape, surrounded by an accretion disk of matter that constantly feeds it, shooting off relativistic jets in either direction.
Image credit: University of Warwick, retrieved from bordermail.com.au.
This is a pretty accurate picture of active black holes. But most black holes aren't active, and of the ones that are, they aren't active most of the time!
Most people…
esiegel | March 5, 2012"I soon became convinced... that all the theorizing would be empty brain exercise and therefore a waste of time unless one first ascertained what the population of the Universe really consists of." -Fritz Zwicky
You very likely know that there are four fundamental forces in the Universe: gravity, electromagnetism, and the weak and strong nuclear forces. While only some particles experience the nuclear and electromagnetic forces, anything with mass or energy -- which is everything we know of -- is subject to gravity.
Image credit: CountInfinity by Ananth.
The strong nuclear force binds all…
esiegel | February 28, 2012"One mustn't look at the abyss, because there is at the bottom an inexpressible charm which attracts us." -Gustave Flaubert
The deepest depths of space, out beyond our atmosphere, our Solar System, and even our galaxy, hold the richness of the great Universe beyond. Stretching for billions of light years in every direction, there are structures large and small, dense and sparse, everywhere we've ever dared to look.
Image credit: R. Jay GaBany, Cosmotography.com.
In addition to the visible, luminous matter we see in the image above, there's both non-luminous normal matter and dark matter.…
esiegel | February 15, 2012"What's that star?
It's the Death Star.
What does it do?
It does Death. It does Death, buddy. Get out of my way!" -Eddie Izzard
Like it was for many people, the original, very first Star Wars movie was one of my favorites as a child. And while there was a lot to be in awe of, the idea of jetting around the Universe in your own private, gargantuan structure, free from planets, Solar Systems, and even the rest of the galaxy was simply the most amazing idea to me.
Image credit: Star Wars' Wookieepedia.
That's what I wanted: a Death Star. Of course, you know what happens to the Death Star, don'…
esiegel | February 8, 2012"It took less than an hour to make the atoms, a few hundred million years to make the stars and planets, but five billion years to make man!" -George Gamow
Let's pretend that, for all of our history on Earth, we had never once bothered to look up with any instruments beyond what our own eyes could offer. Imagine that all the technology we'd have would be the same -- telescopes, electronics, GPS, etc. -- as would our fundamental scientific knowledge -- Einstein's General Relativity, the Standard Model of Particle Physics, etc. -- but we had just never bothered to turn our attentions toward the…
esiegel | January 30, 2012"In science, "fact" can only mean "confirmed to such a degree that it would be perverse to withhold provisional assent." I suppose that apples might start to rise tomorrow, but the possibility does not merit equal time in physics classrooms." -Stephen Jay Gould
Those of you who follow me on either google+, facebook or twitter know that I sometimes post interesting articles about science from around the world, including this very good article about myths about outer space, from the often-entertaining cracked.com. So, as you can imagine, I was (at first) very excited when I saw this article…
esiegel | December 2, 2011"I have long held an opinion... that the various forms under which the forces of matter are made manifest have one common origin; or, in other words, are so directly related and mutually dependent, that they are convertible, as it were, one into another, and possess equivalents of power in their action." -Michael Faraday
For centuries, the idea that you can't get something for nothing was floating around long before we knew about the most important conservation law in all of the Universe: the Conservation of Energy.
Image credit: Mr. Torgerson's 6th grade class.
For example, the ball…
esiegel | November 2, 2011"The pages are still blank, but there is a miraculous feeling of the words being there, written in invisible ink and clamoring to become visible." -Vladimir Nabokov
The wonderful images we take of deep space -- from distant galaxies to all the stars, clusters, and nebulae within our own galaxy -- all have something in common.
Image credit: Wolfgang Brandner, Eva K. Grebel, You-Hua Chu, and NASA.
Light! More specifically, electromagnetic radiation. While this light isn't always in the visible portion of the spectrum, that's certainly the type of radiation we're most accustomed to. And that's…
esiegel | October 28, 2011"Every true, eternal problem is an equally true, eternal fault; every answer an atonement, every realisation an improvement." -Otto Weininger
The best measurements of the distant Universe -- out beyond our galaxy -- have led us to the current picture of exactly what our Universe is doing: expanding and cooling, with its galaxies progressively getting farther and farther apart.
Image credit: Molly Read for the University of Wisconsin-Madison.
But what does that mean for our past?
If we're expanding and cooling, that means our past was less expanded and less cooled, or as we like to think of…
esiegel | October 21, 2011"By now you must know that your father can never be turned from the Dark Side. So will it be with you." -Emperor Palpatine, Return of the Jedi
You've heard about dark matter. It's the notion that the Universe is somehow very much different than the small corner of it that we're most familiar with.
Photo credit: International Astronomical Union, retrieved from bbc.co.uk.
When we look at our Solar System, we can add up all the rocky planets, the gas giants, the asteroids, moons, and comets, as well as the entire Kuiper belt, and find out just how much of our neighborhood is dark.
And we can…
esiegel | October 11, 2011"The best way to escape from a problem is to solve it." -Alan Saporta
One of the greatest puzzles in the Universe today is just why the Universe is structured the way it is.
Image credit: Robert Gendler / Hubble Legacy Archive.
For the individual galaxies that we see, the puzzle is why they rotate at the speeds they do. If the only matter in these galaxies were normal matter (made out of protons, neutrons, electrons, etc.), the outskirts of these galaxies would rotate around their centers much more slowly than they actually do.
Image credit: Victor Andersen, University of Alabama, KPNO,…
esiegel | September 22, 2011"A fact never went into partnership with a miracle. Truth scorns the assistance of wonders. A fact will fit every other fact in the universe, and that is how you can tell whether it is or is not a fact. A lie will not fit anything except another lie."
-Robert Green Ingersoll
One of the most amazing facts to comprehend about the Universe is that it actually is comprehensible! A few basic laws, properties and particles, given our current understanding, can take us from a hot, dense, nearly uniform Universe to the complexity of the billions of stars within the billions of galaxies we see today…
esiegel | August 18, 2011"The only relevant test of the validity of a hypothesis is comparison of prediction with experience." -Milton Friedman
Dark matter is one of the most important components of the Universe today. And yet in the public's eye, almost no one accepts it the way, say, the Big Bang is accepted. But it should be, and I'll show you why.
Image credit: NASA / ESA / Marc Davis.
I've talked before about what it took to convince me that dark matter was the best theory out there (and gave a simpler version here), but -- with alternative theories making big headlines -- it's important to truly know why dark…
esiegel | August 16, 2011"Men occasionally stumble over the truth, but most of them pick themselves up and hurry off as if nothing had happened." -Winston Churchill
It's often said that you can't get something from nothing. And while this may be true for most practical applications of your life, it isn't true for our physical Universe.
And I don't just mean some tiny part of it; I mean all of it. When you take a look at the Universe out there, whether you're looking at the wonders of this world or all that we can see for billions of light years, it's hard not to wonder -- at some point -- where it all came from.…
esiegel | August 5, 2011"A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it." -Max Planck
(For Alan L., from the comments on this post.)
When you look out at the night sky, with the deepest, sharpest eyes possible, what is it that you see?
Image credit: NASA, ESA, R. Windhorst, S. Cohen, M. Mechtley, M. Rutkowski, R. O'Connell, P. McCarthy, N. Hathi, R. Ryan, H. Yan, and A. Koekemoer.
Galaxies! Lit by hundreds of billions of suns each (and that's just on average),…
esiegel | August 1, 2011"Keep up the good work, if only for a while, if only for the twinkling of a tiny galaxy." -Wislawa Szymborska
Our Milky Way Galaxy is home to not only our Earth and our Solar System, but hundreds of billions of other stars.
Image credit: Aarne Bielefeldt.
Held together by not only the incredible gravity of all of our stars, but by dark gas and dust far outweighing all the stars, and by trillions of suns worth of dark matter as well, our galaxy represents one of perhaps a hundred billion just like it in our vast Universe.
Image credit: NASA, ESA, R. Windhorst, S. Cohen, M. Mechtley, M.…
esiegel | July 29, 2011"It has been rightly said that nothing is unimportant, nothing powerless in the universe; a single atom can dissolve everything, and save everything! What terror! There lies the eternal distinction between good and evil." -Gerard De Nerval
(For Rich C. and Sili, for their questions on this post.)
The humble hydrogen atom -- one proton and one electron, bound together -- is the most common form of normal matter in the entire Universe. When you look out at all the galaxies in the Universe, what you're seeing is predominantly light coming from those simple hydrogen atoms fusing together at the…