Physics
esiegel | July 6, 2009We have come so far in the last 100 years, and so has our picture of the Universe. From an island galaxy ruled by Newton's gravity and classical electromagnetism, we've come through the discovery of general relativity, the expanding Universe, the need for dark matter, the big bang, the synthesis of all the elements in the Universe, and, for good measure, we walked on the Moon. By the 1970s, we had a fabulous picture of the History of the Universe.
There's just one (huge) problem: What caused the Big Bang? We know the laws of gravity and quantum mechanics, and we know that the Universe is…
rallain | July 6, 2009July 4th can be fun. One activity my family enjoys is playing in the lake at my parents house. Along with this comes the jumping off the dock. Great fun, and great physics. Here is a short clip.
Work Energy Example from Rhett Allain on Vimeo.
Notice that I violated my own rules for making videos. In particular, the camera was not perpendicular to the motion. Also, I can handle panning cameras, but not when there is nothing but sky in the background. This video is therefore not appropriate for a video analysis. That is ok. I don't need it to talk about physics. So, here is the…
drorzel | July 5, 2009I've been enjoying Tom Levenson's "Diary of a Trade Book" series quite a bit (the latest post is on cover art), so when I say a stack of copies of Newton and the Counterfeiter: The Unknown Detective Career of the World's Greatest Scientist at the bookstore the other day, I snapped one up.
As the title suggests, it's a little like CSI: London 1697, with a good deal of detail about how Newton built a court case against the notorious "coiner" and con man William Chaloner, who earned Newton's personal enmity by not only passing fake coins, but by spreading stories of incompetence and corruption…
rallain | July 4, 2009I created another screen cast showing how to get started with a numerical calculation for one of my classes. In this case, the students are attempting to model the motion of an object falling with air resistance. The following example doesn't show the steps including the air resistance, but maybe it is enough to get someone started.
Record your screencast online
pontiff | July 2, 2009DARPA, you know the people who invented the internet ("100 geniuses connected by a travel agent"), has a new director:
The Department of Defense (DoD) today announced the appointment of Regina E. Dugan as the 19th director of the Defense Advanced Research Projects Agency (DARPA). DARPA is the principal agency within the DoD for research, development, and demonstration of concepts, devices, and systems that provide highly advanced military capabilities for the current and future combat force. In this role of developing high-risk, high-payoff projects, DARPA compliments and balances the…
pontiff | July 2, 2009
ArXiview, my arXiv browsing iPhone app, has been updated for the new iPhone OS 3.0. New features include:
Search fields now accept boolean queries and exact phrase queries. Touch the little (i) icon to get info on this feature from the search page.
Search by identifier has been added.
There is now an in application emailer. So when you want to email yourself a reference the program doesn't quit out of the app.
Added the cond-mat category for quantum gases.
The app now sorts resorts in reverse chronological order.
A bunch of bug fixes (search by category in particular was acting buggy.)…
drorzel | July 1, 2009I no longer recall who pointed me to this current.com post titled "Scientists Make Radio Waves Travel Faster Than Light "-- somebody on Facebook, I think. As it would be a pretty neat trick to make light move faster than light, I took a look. The opening is fairly standard semi-gibberish:
Scientist John Singleton insists that Albert Einstein wouldn't be mad at him, even though at first blush Singleton appears to have twisted the famous physicist's theories about light into a pretzel.
Most people think Einstein said that nothing can travel faster than the speed of light, but that's not really…
drorzel | June 30, 2009Over at Confused on a Higher Level, Melissa has been thinking about undergraduate research:
As a member of the Physics and Astronomy Division of the Council of Undergraduate Research (CUR), over the past few months I've gotten several e-mails about the effort by CUR, the Society of Physics Students, the American Astronomical Society, and the American Physical Society Committee on Education to adopt a statement on undergraduate research. The CUR statement reads as follows, "We call upon this nation's physics and astronomy departments to provide, as an element of best practice, all…
emjohnson | June 30, 2009On June 30, 1905 Albert Einstein published his paper on Special Relativity with the paper "On the Electrodynamics of Moving Bodies" in the journal Annalen der Physik (original German version in pdf here).
This was Einstein's third of what have become known as the Annus Mirabilis papers (Latin for "extraordinary year") and revolutionized the field of physics by reconciling Maxwell's equations for electricity and magnetism with the laws of mechanics. He was 26 years old. In this paper Einstein also dispelled with the concept of "luminiferous ether" (proposed by Isaac Newton in 1704), a…
rallain | June 29, 2009Slate's Explainer has an answer and question post about moonwalking. Here is one of the very good questions answered there.
Would it be easier to moonwalk on the moon?
The Explainer says "absolutely not" and attributes this to the awkwardness of walking on the moon. The article gives an example of Earthly legs being too powerful as the "astronaut's hop". The explainer also says it is awkward because of the pressurized space suits.
I think the problem is almost entirely the pressurized suits. I believe that the astronauts do their moon-hop because it is difficult to bend their legs in the…
rallain | June 29, 2009I finally saw the movie Hancock. Yes, I know it has been out for a long time but I don't get out much. You know me, I can't leave something like this well enough alone. It's not my fault, I was born this way. It shouldn't spoil the movie too much if I tell you this one scene (you have probably already seen it anyway).
Basically, Hancock gets upset with this boy and throws him in the air to scare him or something. In case you did not time it, the kid was in the air for 23 seconds. I claim that in order for Hancock to throw a person in the air for this long, the acceleration during…
esiegel | June 29, 2009The Earth is one of those extremely rare, special places in the Universe where water can exist, stably, as a liquid. So much of it exists here on Earth, that if you were to add up all the oceans on Earth together, it would weigh more than 10^18 tonnes, more massive than the biggest asteroid ever, and about as massive as Pluto's giant moon, Charon.
But water only has a very small window in which it can be a liquid. For instance, if you took some warm water up to a very high elevation, it would start to boil, and become a gas! The higher up you took it, the lower and lower your boiling point…
drorzel | June 29, 2009The National Science Foundation uses a computerized proposal-and-report submission system called FastLane. When I first submitted a proposal, this required three things to log in: your last name, your Social Security number, and a password of your choice.
Sometime in the last year, they stopped using the SSN, and switched to a randomly generated nine-digit ID number. Which they sent me in a massage that somehow manages not to include the strings "NSF," "FastLane," or "National Science Foundation." "ID" by itself returns too many results in GMail to be useful.
On the bright side, at least I…
drorzel | June 29, 2009I'm not entirely sure why I keep responding to this, but Bruce Charlton left another comment about the supposed dullness of modern science that has me wondering about academic:
The key point is that a few decades ago an average scientist would start working on the problem of his choice in his mid- to late-twenties - now it is more likely to be early forties or never.
In the UK most people got a 'tenured' university lectureship straight after their PhD (or before) - created a lot of 'dead wood' but also gave people time and security to be ambitious.
Longer time spent as a doctoral student plus…
drorzel | June 29, 2009While I've seen him on tv a bunch of times (both on NOVA and on the Comedy Central fake-news shows), I have somehow managed not to read anything by Neil deGrasse Tyson before. I'm not sure how that happened. After his appearance on The Daily show last year, and especially after the Rubik's Cube thing the next day, I figured I needed to read something of his, so I picked up a copy of Death by Black Hole and Other Cosmic Quandaries. Kate actually got to it before me (I was working on my own book, and didn't have much time for reading other people's non-fiction), but it's been serving as bedtime…
grrlscientist | June 27, 2009tags: Weekend Project, Potato Gatling Gun, DeRose family, trailer, entertainment, engineering, physics, streaming video
Do you wish you could do something fun with your family? This video shows how one family designed and built a potato gatling gun, which was shown at this year's Maker Faire. This looks like so much fun that it almost makes me want to have kids! [4:29]
esiegel | June 26, 2009Or, to put it as one of my readers/questioners did,
Why doesn't the Space Needle, a top-heavy skyscraper, ever tip over and fall?
This is reasonable, and there's precedent for this. After all, the Leaning Tower of Pisa was falling over, and needed significant foundation-work just to keep it upright.
Now, when you take something like the Space Needle, it looks like most of the weight is in the top:
And it looks even more significant if you stand at the bottom and look up:
Yet, in actuality, the Space Needle is one of the most stable structures ever, and will be one of the last buildings…
rallain | June 26, 2009Was the moonwalk fake? No, not the Apollo landings. I am talking about Michael Jackson's moonwalk. You got to admit, he had a big impact on a lot of stuff and this is my way to give him respect - physics.
I am sure you know about the moonwalk. Maybe you can even do the dance move yourself, but how does it work? First, here is a clip of MJ doing his stuff.
As a side note, I can't remember where I saw it but there was a great discussion of the history of the moonwalk. If I recall correctly, some were saying Michael didn't create this move. One thing is for sure, he made it popular. Now…
pontiff | June 25, 2009Not sure what it's good for, but heck I'd love to play with one :)
DaVinci (Microsoft Surface Physics Illustrator) from Razorfish - Emerging Experiences on Vimeo.
esiegel | June 25, 2009Earlier this week, I wrote about how the heavier elements in the Universe were made. Specifically, that they are made in stars. These stars then explode in a variety of ways, enriching the Universe with these heavy elements, and allowing us to form glorious things, like our planet!
By contrast, the big bang makes light elements, but not heavy ones. Why is this the case, and how do we know? Let's find out.
Image credit: Stephen Van Vuuren, created from a simulation of 80,000 star images.
Just a few seconds after the big bang, the Universe is filled with protons and neutrons, in roughly the…