Large Hardon Collider

[Chun Liroy]

I think the one that test dividing one wouldn't be all that difficult. Simple if and do while statement using the % operator should get it done, I think.
x=2
While ( x<sqrtn (idk how to get that lol))
{
if (x%n == 0)
return not prime;
else x++;
}

Kind of inefficient since that will check all even numbers even though it should skip them if 2 doesn't work, but would that work?

Edit 2: oh nvm then :X I'm limited in my programming knowledge.

[Eliseos]

Yeah, it would be easy if it wasn't assembly. No real control statements in assembly, nor a % operator. We have an IDIV operation but we don't get a remainder flag.

Edit: Hmm, it appears the IDIV op code places a remainder in one of the accumulators. That should be easy enough, but finding the square root of n is still a bit of a challenge.

Edit 2: There's also a branch if the last operation resulted in zero, could check if the remainder accumulator is zero and if it is, then the number isn't prime.

[Woozie]

I took Advanced Linear instead of Number Theory, so I can't help. Blame my school for letting theoretical math majors skip such an important class.

[Eliseos]

Damn it Akron.

Do you have any good methods for computing sqrt(n), without using a method that involves "guessing" at the correct value? Right now I'm looking at http://en.wikipedia.org/wiki/Methods..._.28base_10.29 as my best bet in such a low level language.

Edit: I should say that I can specify a number as base 2,10, or 16 in this system. It'd just be finding something suitable.

Edit 2: I think I'm just going to write a large loop that takes the number n, goes through the squares, and once it finds a value larger than n, the number before it is the integer portion of the square root. Seems easiest to implement anyways (if a bit inefficient, but fuck it). I'm not going to really care about rounding.

[Woozie]

I suck at all things programming, but I think the easiest way to find sqrt(n) would be to solve the polynomial x^2-n=0. There are tons of methods out there for finding zeros to polynomials. We spent like a month on that in numerical methods. If I still had my book I'd just tell you the easiest way we did it (I never bought the book, I borrowed one from the professor).

Edit: And I don't know what you mean by guessing and checking, but most of the methods we used did require an initial guess. Then we iterated until we got the level of accuracy we wanted. There are ways of picking a good initial guess so that your answer will converge fast.

[Ferion]

Sorry to derail a little bit, I know you said you never took the class Woozie, but since a lot of what you work with is pure mathematics, how difficult would you say number theory is? I need to take a summer math class and my choices are basically either number theory or graph theory. I'm only asking because I really have no idea what to expect, I can't seem to get a decent syllabus or find a torrent for the text book. I took Set Theory and thought it was pretty hard once we got past the basics, but to be honest I didn't really spend much time with it and my professor was awful. I did pretty decent in Advanced Calc, but not amazing, if that gives you some kind of idea of my proof abilities.

[Eliseos]

Edit: And I don't know what you mean by guessing and checking, but most of the methods we used did require an initial guess. Then we iterated until we got the level of accuracy we wanted. There are ways of picking a good initial guess so that your answer will converge fast.

Yeah, I meant more what you said. Some value is "picked" (no idea how) and then its accuracy is refined from there.

[Woozie]

I don't have any clue how difficult Number Theory is, but I've never heard anyone complain about it. I don't know if that's because it's not harder than the other classes they're taking or if it's because no one is taking it.

[Woozie]

Yeah, I meant more what you said. Some value is "picked" (no idea how) and then its accuracy is refined from there.

The book I had gave methods for picking the numbers. For a nice polynomial like x^2-n, I'm pretty sure you'll get fast convergence no matter what you pick.

[Woozie]

This is for you, Miz (from Random Image Thread)

[Mizango]

ROFL, win.

[Eliseos]

Astrology and physics will get all the bitches.

[Mizango]

Astrology and physics will get all the bitches.

For real. If anything you will definitely find the closet freaks.

[Tyche]

http://gizmodo.com/#!5798294/amateur-astrographer-creates-largest+ever-night-sky-panorama

http://fastcache.gawkerassets.com/as...5/nightsky.jpg


Amateur Astrographer Creates Largest-Ever Night Sky Panorama



One day, Nick Risinger, a 28-year-old marketing director in Seattle, felt like he needed a change. So he quit his job, packed up six professional astronomical cameras, and hiked 60,000 miles through western United States and South Africa, taking 37,000 color pictures of the night sky.

The result? This 5000-megapixel interactive, zoomable map showing our full Milky Way galaxy, stars, planets, and the nebulae surrounding it. It's the largest-ever, 360 degree panorama of the heavens—all created by this first-time astrographer. What's even more remarkable is that it's considered better than previous professional sky surveys—like the Digitized Sky Survey of the 1980s—which were shot only in red and blue.

According to the Risinger, his aim was to create an image that had more real feeling: "I wanted to create something that was a true representation of how we could see it, if it were 3,000 times brighter," he said And lucky for us, he's made it freely available to the public. You can see the incredible Phototopic Sky Survey right here: [Sky Survey via Wired]

[Kaylia]

I'm going to forward this panorama to many people, this is badass. The mode that overlap information on top of the picture is pretty cool too.

Also, I wonder if the smallest dot when you zoom in are stars and galaxies, or just noise.

[Eliseos]

More NASA doin work:

NASA's Gravity Probe B Confirms Two Einstein Space-Time Theories
05.04.11


http://www.nasa.gov/images/content/1...ng_web_330.jpg Artist concept of Gravity Probe B spacecraft in orbit around the Earth. Image Credit: Stanford
NASA's Gravity Probe B (GP-B) mission has confirmed two key predictions derived from Albert Einstein's general theory of relativity, which the spacecraft was designed to test.

The experiment, launched in 2004, used four ultra-precise gyroscopes to measure the hypothesized geodetic effect, the warping of space and time around a gravitational body, and frame-dragging, the amount a spinning object pulls space and time with it as it rotates.

GP-B determined both effects with unprecedented precision by pointing at a single star, IM Pegasi, while in a polar orbit around Earth. If gravity did not affect space and time, GP-B's gyroscopes would point in the same direction forever while in orbit. But in confirmation of Einstein's theories, the gyroscopes experienced measurable, minute changes in the direction of their spin, while Earth's gravity pulled at them.

The findings are online in the journal Physical Review Letters.

"Imagine the Earth as if it were immersed in honey. As the planet rotates, the honey around it would swirl, and it's the same with space and time," said Francis Everitt, GP-B principal investigator at Stanford University. "GP-B confirmed two of the most profound predictions of Einstein's universe, having far-reaching implications across astrophysics research. Likewise, the decades of technological innovation behind the mission will have a lasting legacy on Earth and in space."

GP-B is one of the longest running projects in NASA history, with agency involvement starting in the fall of 1963 with initial funding to develop a relativity gyroscope experiment. Subsequent decades of development led to groundbreaking technologies to control environmental disturbances on spacecraft, such as aerodynamic drag, magnetic fields and thermal variations. The mission's star tracker and gyroscopes were the most precise ever designed and produced.

GP-B completed its data collection operations and was decommissioned in December 2010.

"The mission results will have a long-term impact on the work of theoretical physicists," said Bill Danchi, senior astrophysicist and program scientist at NASA Headquarters in Washington. "Every future challenge to Einstein's theories of general relativity will have to seek more precise measurements than the remarkable work GP-B accomplished."

Innovations enabled by GP-B have been used in GPS technologies that allow airplanes to land unaided. Additional GP-B technologies were applied to NASA's Cosmic Background Explorer mission, which accurately determined the universe's background radiation. That measurement is the underpinning of the big-bang theory, and led to the Nobel Prize for NASA physicist John Mather.

The drag-free satellite concept pioneered by GP-B made a number of Earth-observing satellites possible, including NASA's Gravity Recovery and Climate Experiment and the European Space Agency's Gravity field and steady-state Ocean Circulation Explorer. These satellites provide the most precise measurements of the shape of the Earth, critical for precise navigation on land and sea, and understanding the relationship between ocean circulation and climate patterns.

GP-B also advanced the frontiers of knowledge and provided a practical training ground for 100 doctoral students and 15 master's degree candidates at universities across the United States. More than 350 undergraduates and more than four dozen high school students also worked on the project with leading scientists and aerospace engineers from industry and government. One undergraduate student who worked on GP-B became the first American woman in space, Sally Ride. Another was Eric Cornell who won the Nobel Prize in Physics in 2001.

"GP-B adds to the knowledge base on relativity in important ways and its positive impact will be felt in the careers of students whose educations were enriched by the project," said Ed Weiler, associate administrator for the Science Mission Directorate at NASA Headquarters.

NASA's Marshall Space Flight Center in Huntsville, Ala., managed the Gravity Probe-B program for the agency. Stanford University, NASA's prime contractor for the mission, conceived the experiment and was responsible for the design and integration of the science instrument, mission operations and data analysis. Lockheed Martin Corp. of Huntsville designed, integrated and tested the space vehicle and some of its major payload components.

For more information about Gravity Probe B, visit:

http://www.nasa.gov/mission_pages/gpb/

http://www.nasa.gov/mission_pages/gpb/gpb_results.html

I thought frame-dragging had already been proven, and the geodetic effect proven by gravitational lensing, but NASA says no. I guess this is just more precise work? Halp cosmetologists.

[Woozie]

http://gizmodo.com/#!5798294/amateur-astrographer-creates-largest+ever-night-sky-panorama

Holy crap, how did I miss this? This is so awesome.

More NASA doin work:



http://www.nasa.gov/mission_pages/gpb/gpb_results.html

I thought frame-dragging had already been proven, and the geodetic effect proven by gravitational lensing, but NASA says no. I guess this is just more precise work? Halp cosmetologists.

I never even knew about frame-dragging. Maybe I should actually study GR someday. I'm tired of never knowing what my astrophysics/cosmology friends are talking about.

It's interesting that a theory that one man came up with based partially on thought experiments turned out to be so accurate today. I'm not sure how much data he had to look at to base his theories on. The stories about him makes it sound like he just came up with it based on what "seemed" right to him, which would be even more remarkable if it's true. Either way, for QM to reach it's current level of success and accuracy, it took hundreds of physicists decades of studying, refining, and experimenting. GM took one man 10 years at most who wasn't even capable of doing most of the experiments the theory needed.

-----------------------------------------------------------------------------------------

By the way, for anyone who hasn't learned LaTex yet, it turns out it's much easier than expected. All this time I've been using codcogs to write Latex equations on these forums, I've been unknowingly learning half the stuff I need to know to use LaTex. I no longer have to look up every single symbol I need, which saves a LOT of time compared to the last few times I've tried to use LaTex. I took this guy's suggestion last night:

Install Miktex
Intall tecnixcenter (forgot if it spell like this) - so far it only works in win xp, I can't let it work on win 7

use this as a reference

http://www.maths.tcd.ie/~dwilkins/LaTeXPrimer/
http://en.wikibooks.org/wiki/LaTeX/B...phy_Management

open amsmath, graphicx manual

Find a simple lab report, and type it in latex.

after 1~2months

congratulations, you are familiar with latex

downloaded winedit was well

http://www.winedt.com/

watched this video

http://www.youtube.com/watch?v=mVq16Tl_W20

And read the book

http://www.amazon.com/Math-Into-LaTe.../dp/0817641319

(PM me if you want the PDF)

That book can be read in one night. It's one short, simple chapter on using LaTex and then 50 pages of tables/appendix/etc, stuff you'll look up if you get stuck.

I now feel stupid for typing up that 11 page paper in word last week. If I had just spent one night on this, I probably would have been faster on LaTex than on word (and plus I would have gotten a lot of practice with LaTex in the process). I guess my thesis will give me plenty of practice

[Eliseos]

I never even knew about frame-dragging. Maybe I should actually study GR someday. I'm tired of never knowing what my astrophysics/cosmology friends are talking about.

It's interesting that a theory that one man came up with based partially on thought experiments turned out to be so accurate today. I'm not sure how much data he had to look at to base his theories on. The stories about him makes it sound like he just came up with it based on what "seemed" right to him, which would be even more remarkable if it's true. Either way, for QM to reach it's current level of success and accuracy, it took hundreds of physicists decades of studying, refining, and experimenting. GM took one man 10 years at most who wasn't even capable of doing most of the experiments the theory needed.

Yeah lol, even before he started on GR, he explained three major things while he was working in that patent office. Brownian motion, photoelectric effect (which was what lead to his Nobel) and SR were all explained by him in a relatively short time, and early on in his life. Dude didn't even do well in his undergrad classes because he just got bored. He's a genius on all sorts of levels. He had to have been visited by aliens to get all this shit right

[zoobernut]

http://www.popsci.com/technology/art...x-around-earth

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NASA Gravity Experiment Finds Space-Time Vortex Around Earth, Like a Vat of Fourth-Dimensional Molasses
Gravity probe experiment used the most perfect spheres ever created
By Rebecca BoylePosted 05.05.2011 at 10:44 am26 Comments

Perfect Spheres The spheres inside GP-B's gyroscopes are considered the world's most perfect spheres, yet tiny aberrations forced scientists to perform updated calculations to make sure their observations were correct. Stanford University
Like a beach chair sagging under a sunbather’s weight, the fabric of spacetime does indeed warp around the mass of the Earth — just as Albert Einstein predicted. And like a swimmer moving through the water, the rotation of the Earth affects the movement of spacetime itself. A gravity probe whose origins date to the era before human spaceflight has finally proved general relativity right, according to NASA.
The Gravity Probe-B measured the geodetic effect, the amount that Earth warps the space and time in which it sits, and frame-dragging, or the extent that Earth’s rotation churns spacetime around with it.
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TAGS
Technology, Rebecca Boyle, Einstein, general relativity, gravity, gravity probe b, nasa, satellites, spacetime, VORTEX, warpEinstein’s theories of relativity hold that space and time are woven together into a four-dimensional fabric, and that a weighty body like a planet or a star depresses that fabric, like someone sitting on a chair or a trampoline. Gravitational attraction is really just objects following the warped path.
What’s more, the rotation of a massive body would also affect the fabric, so that a distant observer would perceive objects close to a gravitational body as being dragged around. Think of Earth sitting in a vat of liquid — as the planet rotates, the liquid starts to swirl, too, and so does everything near the Earth.
If this is true, the axis of a gyroscope would change when compared to the light from a faraway star. This is what GP-B was designed to do.
Orbiting 400 miles above the Earth in a polar orbit, GP-B contains four gyroscopes made of quartz-silicon spheres that are considered nearly perfect — they’re in the Guinness Book of World Records. It has a telescope that stared at a single star, IM Pegasi, while the satellite made its rounds. If the Earth’s mass did not affect spacetime, the gyroscopes would point the same direction forever. But they didn’t, experiencing teeny but measurable changes in the direction of their spin. This is exactly what Einstein predicted back in 1916.

Gravity Probe-B and the Geodetic Effect: Stanford University
For those who are interested, it measured a geodetic precession (spacetime depression) of 6.600 arcseconds, plus or minus 0.017, and a frame-dragging effect of 0.039 arcseconds, plus or minus 0.007, according to lead researcher Francis Everitt at Stanford University. An arcsecond is 1/3600th of a degree. The satellite’s precision is thus equivalent to measuring the thickness of a sheet of paper edge-on from 100 miles away, according to an email from NASA. The calculations, published online in Physical Review Letters, mesh with Einstein’s predictions.
Scientists are calling it an “epic result,” and NASA announced the news at a press conference today. The success is despite the many twists and turns GP-B has experienced in its long life, from conception in 1959 to its eventual launch in 2004. It required new innovations along the way, including technology that can reduce drag, temperature fluctuations and magnetic influences on orbiting satellites. GP-B technologies are used in GPS equipment and were used on NASA's Cosmic Background Explorer mission, which determined the cosmic microwave background. After finally launching in 2004, GP-B ran out of funding in 2008 before researchers in Saudi Arabia stepped in.
GP-B’s legacy will be this verification of relativity, said Clifford Will, a relativity expert at Washington University in St. Louis.
“One day this will be written up in textbooks as one of the classic experiments in the history of physics,” he said.
[NASA Science News]

Another article similar to the one that Eliseos posted it might contain some slightly different information.

If you can look at the article they have a really cool photo of the gyroscope objects used.

[Plow]