When interstellar clouds of gas and dust start to knot up or are compressed by a shockwave from a nearby supernova, they start to gravitationally collapse. The higher density draws in more material and eventually a star starts to form in the center with a disk of dust and gas encircling it...
Very interesting, thanks for sharing.
Feynman was really brilliant and is often listed as a major figure that physicists respect and aspire to the level of. I want to read that book now ...
It's also interesting because it kind of demonstrates that weather you are using modern computers...
I know the way my parameter file is handled isn't ideal, I've just been focusing my efforts on getting the number crunching portion of it to run (^_^;). I'm the only one who uses it, so I've been careful about keeping my parameter file in order, it's that is definitely on the to-fix list!
I believe I've solved my problem, which is quite a different problem from what I thought it was!
My program reads some initial parameters from a text file. Some of them are of type bool and were read like this:
bool sourcediscrimination;
getline(infile, line);
position =...
@Ancalagon44 - It does both actually. It does a lot of FP calculations with doubles in one stage, then int calculations in another. It constantly flips back and forth between these two stages.
I appreciate everyone's input, the Google performance tool will be helpful. Right now though I'm...
@Schmide - the Linux machine has 2.4 Ghz Core2Duo P8600 with 3mb cache and the Macbook has a 2.16 Ghz Core2Duo T7400 with 4mb cache. Cache affects performance on memory heavy, number crunching apps (which this is), but I wouldn't expect this big of a difference between those two.
I've had...
Thanks for the responses.
@degipson - I saw that but posted here hoping for a variety of ideas and to her personal preferences on the tools for the job.
As for the other questions, I don't think the hard drive is particularly relevant as it's not accessed while the program is running on...
On OS X under Activity Monitor I can choose "sample process" and see what percentage of time what functions are taking and it's been very useful. Is this what you mean by CPU profile?
I'm not sure how to do it on Linux, any info. you could point me to would be greatly appreciated.
Thanks for the reply.
Libtiff is only used at the end to output an image after a lot of calculation. It represents an extreme minority of the execution time.
Both cores are being utilized to 100% and this can be seen under System Monitor.
The Linux machine has 4 gigs of RAM and the Mac...
Hello.
I'm a hobbyist programmer and have stumbled across a curious problem that I hope someone can give me some insight on.
I wrote an app in C++ using g++ on my OS X 10.6 MacBook. It's command-line only. It reads some numbers from a small TXT file, does a lot of number crunching using...
We've all heard many times how a spoonful of neutron star material would weigh millions of tons (or more) on Earth and such. But what I want to know is if we could theoretically somehow take a spoonful of a neutron star, wouldn't it explode insanely violently the second it was no longer in the...
I am by no means a physics expert, but we know that matter warps the fabric of space-time and too much matter warps it to the point where it curves in on itself (aka blackhole), and physics begins to run crazy.
I heard before that energy (aka radiation) also affects space-time and that...
Great, thanks for the reply!
I can speak and read Japanese, but not with enough proficiency to have it as my computer's default language.
I was fortunate to have the chance to visit Taipei two years ago. I thought it was a pretty cool city!
Hi everyone,
I live in Japan and want to upgrade my Intel Macbook to Snow Leopard. I was wondering if there are different internationalized versions of OS X or if it is just one version where you set the region upon installation? I am considering ordering it from the Japanese amazon.com web...
The drifting away of the Moon is clearly explained via a mechanism other than cosmic expansion. If you measure the rotation period of the Moon around the Earth, the rotation (day length) of the Earth, and the forces the tidal bulge that the Moon causes on the Earth and how the tidal bulge...
I wanted something different to play with so I bought myself a Macbook at work and bootcamp'd it so I can boot OS X or XP sp2.
Windows doesn't run smoothly. Audio crackles and the system hiccups for tiny fractions of a second where it won't respond (cursor won't move during this time...
There would be a big blast of gamma radiation and spray of particles that pop into existence from the energy levels (based on e=mc^2) and that would fry everything at that instant, but there wouldn't be decaying particles leftover releasing radiation ... which is the case in a nuclear fission...
I've been reading about astronomy and bit and watching a few documentaries and I heard two things that at first sounded like they may have been different reasons for fusion in stars, but after thinking I'm wondering if they aren't different views of the same thing ...
Stars form when large...
Quick question - if you plug a typical USB Ethernet adaptor into a Windows XP PC, do they just work like USB flash drives, or do they require a driver that they come with to be loaded?
I'm considering buying a few as a workaround for some networkign clunkyness at work, but have never used...
Kelvin and Celsius degrees are the same. Its just that 0 Kelvin is -273.15 deg. celcius (absolute zero if I understand correctly.) When talking about quadrillions, a few hundred is meaningless :-P
Yeah, I guess a nuke would give more of a kick than a satellite type thing if we were in dire straights and were willing to risk breaking up the asteroid.
The tests that the original link pointed to were engineering proof of concept tests that were planned. It would probably a little hard to...
Firing reverse thrusters is really the only conventional way I can think of. There is no friction in space and if you want to slow down as you approach a body after free journy through space you have to apply as much thrust in reverse to slow you do as it would take to accelerate you to a given...
A mission to Mars and New Horizons is different. New Horizons is going to fly right past Pluto, a mission to Mars would have to stop at Mars (slow down enough to enter orbit) so you would need a ton of fuel to be able to brake ...
Cassini had to fire it's main engine for 2hrs to slow down...
I don't think what you're saying would work. Black holes have a massive gravitational gradient near them due to their compaction, but as you get a few AUs away from the event horizon their pull is the same as the pull of a star of the same mass.
In order to have a runway long enough to hit...
I think the idea would be to speed it up so it crosses a point in Earth's orbit BEFORE Earth does thus just missing us.
If we speed it up and it is ahead of Earth there is no danger. If we slow it down and Earth passes in front of it with the plan being that Earth get's out of the way in the...
Nukes aren't really viable in my eyes for several reasons. The most significant being that there is a very significant chance that it could shatter the asteroid or break up enough of it that rather than having one rock flying at us Earth would have a cosmic shotgun blast. Or at least a...
I just skimmed over that link. While technically informative that article is too technical to be useful to soemoen just learning the basics of a star's lifecycle IMHO.
To make a long complex process short, when the core starts fusing iron the process consumes rather than produces energy (unlike fusing hydrogen.) Without the blast of energy from fusion to stand up against gravity and the rapid cooling caused by iron fusion the core shrinks really fast. The...
I'm no expert, but I'm quite interested and where's what I've gleaned:
We know that gravity increases with mass and we know the equations that govern this.
We also know how much force protons and electrons can stand up against before they get crushed together into neutrons (when a massive...
I realize that my camera is not high quality for this type of thing, but it's what I have to work with. It's surprisingly good for a consumer camera. I've done long exposure shots of LEDs before (specifically the machine room at work with all of the lights turned off) and have always had...
I'm afraid I don't know enough about astronomy to know if it could be a sattelite or space junk or not. I kind of don't suspect that it is because I've seen ground based photos (without a lot of magnification) of satellites before and they were streaks because they are in motion (orbit). Over...
I don't think it was a meteor because that was a 15 second exposure. Anything moving would have appeared as a uniform streak where the front end of it would be the the same thickness as the back end.
I forgot to mention in the original post that this was a long (15 second) exposure. That...
Can anyone help me identify this? http://www.aluminumstudios.com/lj/night_sky2434.jpg
I was in a rural area which was nice and dark with a perfectly clear sky. I could even see some of the Milky Way with my bare eyes. I aimed my Canon PowerShot A85 straight up at around 11:30PM from my...
Solar flares act like particle accelerators and create antimater the same way particle accelerators do.
I don't clearly remember the particles invovled but I believe hydrogen nuclei are slammed together and one of the byproducts is a positron. A massive solar flare can product up to a pound...
I prefer to spend a few extra dollars and get delicate/sensitive/electronics things from established on-line stores and what-not. I don't like dealing with ebay then having to putz around if there are problems.
I've been trying to understand the nature of the incompatibiliteis between quantum mechanics and relativity as well (although on more of a conceptual level than an equation one.) The conclusion I'm coming to that makes sense to me is that relativity says that force of gravity is due to the...
Any time a hard drive starts making a different noise it's time to back up and chuck it ... Hard drives are precision mechanical devices and if something changes to trigger different sounds you can bet it's changed for the worse and will soon die.
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