Relativity
esiegel | September 20, 2013"Observations indicate that the universe is expanding at an ever increasing rate. It will expand forever, getting emptier and darker." -Stephen Hawking
Today's Ask Ethan comes to us via our question/suggestion box from reader MIUFish, who asks:
I read something recently about some people who were doing work looking at the possibility that the mass of things has been decreasing, as an alternate explanation - or, perhaps, interpretation - to some of the questions regarding the expansion of the universe and so on.
Is there any seriousness to this? Do you know anything about it?
Here's what…
esiegel | July 10, 2013"It followed from the special theory of relativity that mass and energy are both but different manifestations of the same thing — a somewhat unfamiliar conception for the average mind." -Albert Einstein
You've heard and seen it plenty of times: Einstein's most famous equation, E = mc2. I've taken you inside this equation before, which lays out how much energy is stored in matter-at-rest, and tells you how much energy you need to create matter in the first place.
Image credit: Niels Madsen, ALPHA / Swansea / CERN.
That's right, you can create matter directly from energy; we do it all the…
esiegel | May 23, 2013“Because dark energy makes up about 70 percent of the content of the universe, it dominates over the matter content. That means dark energy will govern expansion and, ultimately, determine the fate of the universe.” -Eric Linder
It's been a while since we've spoken about dark energy, and we were just talking about Einstein's greatest blunder, so let's just dive right in.
Image credit: S. Beckwith & the HUDF Working Group (STScI), HST, ESA, NASA.
This is our observable Universe, as unveiled by the Hubble Space Telescope. With hundreds of billions of galaxies stretched out some 41…
esiegel | May 17, 2013"Anyone who has never made a mistake has never tried anything new." -Albert Einstein
Back when Einstein first proposed his theory of General Relativity, his revolutionary picture of the Universe was met with a mix of curiosity, awe, and intense skepticism. It isn't every day that your most cherished of all physical theories -- the theory of Newtonian Gravity that had ruled the cosmos for nearly two-and-a-half centuries -- gets challenged by a newcomer.
Image credit: Brooks/Cole - Thomson publishing, 2005.
And yet, that's exactly what Einstein did when he proposed General Relativity at the…
esiegel | May 8, 2013"No valid plans for the future can be made by those who have no capacity for living now." -Alan Watts
"They do not see what lies ahead, when Sun has faded and Moon is dead." -J.R.R. Tolkien
One of the most amazing facts about the Universe is that, despite only having spent a few hundred years studying the fundamental constituents and forces of what makes us up, humanity has been able to accurately figure out just what all this actually is.
Image credit: ESO / S. Brunier.
The laws of nature are almost completely understood in a few, very important senses. We know that our Universe is about…
milhayser | May 7, 2013Walking on two legs, time and space seem universal, but take a good look at the universe, and things start to get mushy. Chad Orzel defines time with a circular-sounding title, writing “there isn’t a giant master clock at the center of the universe that everybody sets their watches by.” Although time can only be measured in ticks, two clocks are seldom in agreement. Chad says “Scientists in Colorado have clocks so good they can measure the change in time from moving at walking speed, or from moving one foot higher in elevation.” On Starts With a Bang, Ethan Siegel revisits the speed of light…
esiegel | May 1, 2013"The views of space and time which I wish to lay before you have sprung from the soil of experimental physics, and therein lies their strength. They are radical. Henceforth space by itself, and time by itself, are doomed to fade away into mere shadows, and only a kind of union of the two will preserve an independent reality." -Hermann Minkowski
When it comes to gravity, you probably think you understand it pretty well.
Image credit: Heavens Above, via http://heavens-above.com/.
Everything with mass (or energy) attracts everything else with mass-or-energy, explaining everything from falling…
esiegel | April 26, 2013"All our sweetest hours fly the fastest." -Virgil
If you've been around the block once or twice, you know that the speed of light in a vacuum -- 299,792,458 meters-per-second -- is the absolute maximum speed that any form of energy in the Universe can travel at. In shorthand, this speed is known as c to physicists.
Image credit: user Fx-1988 of deviantART.
But you or I, no matter how hard we try, will never attain that speed. There's a simple reason for this: we have mass. And for an object with mass, you can accelerate it all you want, but it would take an infinite amount of energy to…
esiegel | March 8, 2013“You wait for a gem in an endless sea of blah.” -Lawrence Grossman
On the one hand, we have General Relativity, our theory of space, time, and gravity.
Image credit: Wikimedia commons user Johnstone; Earth from NASA's Galileo mission.
It describes the Universe on both large and small scales perfectly, from the hot Big Bang to our cold accelerating expansion, from vast superclusters of galaxies down to the interiors of black holes.
Image credit: NASA, ESA, M. Postman (STScI), and the CLASH Team.
But General Relativity doesn't tell us everything. It doesn't tell us, for example, about…
esiegel | March 1, 2013"The mind, once expanded to the dimensions of larger ideas, never returns to its original size." -Oliver Wendell Holmes
When General Relativity supplanted Newton's work as our theory of how gravity works in the Universe, it didn't just change how we view how masses attract, it gave us a new understanding of what the questions where and when actually mean. It gave us the very fabric of spacetime.
Image credit: Christopher Vitale of http://networkologies.wordpress.com/.
What this meant is that no longer could we view objects like matter and radiation as existing in some fixed, grid-like…
esiegel | January 9, 2013"Great spirits have always encountered violent opposition from mediocre minds." -Albert Einstein
It may be hard to believe, seeing as how it's been our leading theory of gravity for nearly a century now, but Einstein's General Relativity is possibly the most frequently challenged scientific idea of all-time. Of course, it's emerged victorious from each and every one of those challenges, making a slew of unintuitive predictions that have been spectacularly confirmed each time they've been tested.
Image credit: Miloslav Druckmuller (Brno U. of Tech.), Peter Aniol, and Vojtech Rusin.
This…
esiegel | December 2, 2012"A truly good book teaches me better than to read it. I must soon lay it down, and commence living on its hint. What I began by reading, I must finish by acting." -Henry David Thoreau
Every day that we have free or leisure time, there's this great conflict as to how we spend it: working to better ourselves and improve our knowledge, and taking the time to enjoy our lives in whatever way we see fit. Sometimes, this goes horribly awry, as the B-52s would attest in their (relatively) new song,
Funplex.
But there's often no better way to combine these two pursuits than by reading a good book.…
esiegel | November 11, 2012“There is no such thing as magic, supernatural, miracle; only something that's still beyond logic of the observer.” -Toba Beta
It might be hard to believe, but science tells us truths about the Universe that we might never have intuited or philosophized about if the Universe itself didn't reveal them to us through investigation. Bap Kennedy alludes to this in one of my favorite songs by him,
Mostly Water,
and this is certainly true of Einstein's relativity, which details just how the Universe behaves when we move close to the speed of light. This is notoriously difficult to visualize or gain…
esiegel | August 27, 2012"You must learn to talk clearly. The jargon of scientific terminology which rolls off your tongues is mental garbage." -Martin H. Fischer
I've always thought that the Universe is absolutely amazing; that everything from the tiniest indivisible particles all the way up to the largest structures and superstructures making up the Universe has an amazing story to tell, if only we can figure out its secrets.
Image credit: Boylan-Kolchin et al. (2009) for the Millenium-II simulation; MPA Garching.
When I first learned some of them for myself, I was a graduate student, immersed in the minutiae and…
esiegel | August 21, 2012"There is a single light of science, and to brighten it anywhere is to brighten it everywhere." -Isaac Asimov
One of the most spectacular and successful ideas of the 20th Century was Einstein's General Relativity, or the idea that matter and energy determines the curvature of spacetime, and the curvature of spacetime in turn determines how gravitation works.
Image credit: Hyper-Mathematics - Uzayzaman / Spacetime.
From the orbits of planets to the bending of starlight, General Relativity governs all gravitational phenomena in the Universe, and accurately describes every observation we've…
esiegel | July 6, 2012"Even if there is only one possible unified theory, it is just a set of rules and equations. What is it that breathes fire into the equations and makes a universe for them to describe?" -Stephen Hawking
After a long search spanning more than my entire lifetime (so far), the Higgs boson has finally been discovered at both detectors -- CMS and ATLAS -- at the Large Hadron Collider at CERN.
Image credit: CERN / Particle Physics for Scottish Schools.
For a little more on this, check out the earlier posts here celebrating Higgs week:
The Biggest Firework of them all: The Higgs
How the Higgs…
esiegel | May 15, 2012"The doctors realized in retrospect that even though most of these dead had also suffered from burns and blast effects, they had absorbed enough radiation to kill them. The rays simply destroyed body cells - caused their nuclei to degenerate and broke their walls." -John Hersey
Everyone (well, almost everyone) recognizes that radiation is bad for you. And the higher the energy of the radiation, the worse it is for you. The reason is relatively straightforward.
Image credit: Environmental Protection Agency.
When high energy particles (or photons) come into contact with normal matter, they…
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 | April 19, 2012"Science progresses best when observations force us to alter our preconceptions." -Vera Rubin
I want you to think about the Universe. The whole thing; about everything that physically exists, both visible and invisible, about the laws of nature that they obey, and about your place in it.
It's a daunting, terrifying, and simultaneously beautiful and wondrous thing, isn't it?
Image credit: NASA, ESA, S. Beckwith (STScI) and the HUDF Team.
After all, we spend our entire lives on one rocky world, that's just one of many planets orbiting our Sun, which is just one star among hundreds of billions…
esiegel | March 16, 2012"The saying 'It's not over 'til the fat lady sings' is erroneous, because women who are fat are never listened to." -Margaret Cho
Last year, the OPERA collaboration made worldwide headlines when they announced the results of a remarkable experiment.
Image credit: OPERA / CERN.
From over 730 kilometers away, in another country, neutrinos were created by one of the most powerful particle accelerators in the world. Protons at over 99.999% the speed of light were smashed into matter, creating a highly collimated beam of neutrinos, which was launched through the Earth at, presumably, speeds…