rvalkass

Energy has one definition, rooted in physical meaning: energy describes the amount of work that a force can perform. We often talk of many 'types' of energy for convenience (in the same way we use mass and energy to refer to the same thing) such as chemical potential energy, kinetic energy, etc. but they are all the same thing. I'm not exactly sure how you want to tie energy to a "physical entity", but it is eternal due to the laws of conservation of energy - it is impossible to create or destroy energy. I'm not sure what you're getting at. If you have particles such as protons that decay after a very long period of time, that particular particle is not eternal. However, its mass-energy obviously is, and will remain constant no matter how the particle decays and what it turns in to. In your diagrams you claimed the object shown contained many hollows and empty spaces, which you said should be included in the volume of the object. The reason I introduced the box was to show that a box has a very low volume (just the volume of the pieces of card that make up its sides) while most of the 'volume' people often talk about is actually a volume of air inside the box. This is analogous to the empty spaces in your diagrams, unless I got the wrong end of the stick? Quantum effects are present in the macroscopic world, they're just incredibly tiny you don't notice. For example, the smallest possible charge (1.6x10-19 C) is always present, but is so small compared to the electric requirements of a toaster that you don't tend to notice it The same goes for effects such as the deBroglie wavelength - it applies to you walking through a doorway, but you'd have to walk so incredibly slow that you'd never get there in the whole history of the universe to date.

No, not necessarily. You can run the beta minus decay in reverse (sort of) and have particles absorbed along with energy to create a heavier particle with less energy. The mass of an object is a property of its constituent parts (the atoms, and the quarks that make those, etc.) and determines how the object is affected by gravitational effects, how its acceleration varies with forces, etc. Energy can be any one of many things, but in this context we car discussing the energy content of an object, which describes the energy 'locked-up' 'inside' an object - energy holding the quarks together, holding the protons and neutrons together, etc. Mass-energy is the two added together, ie. if you converted all the mass to energy and added it to the existing energy, or vice versa, what would the total be? This remains invariant in a closed system. Volume of an object defines the space taken up by the object, not the space it encloses. For example, a box has a fairly low volume (6 thin sheets of cardboard to make the sides) but it encloses a large volume (each of the sides can be fairly long). The volume it encloses is not part of the object.

Topic is resolved.Please PM any moderator to continue this discussion. Until then, this topic is closed.

Particle decay is not the splitting of a nucleus (say, one proton and two neutrons) into two separate nuclei. It is the conversion of quarks from one type to another (in the case of beta decay) with the corresponding emission of particles to satisfy various conservation laws (such as mass-energy, charge, etc). In the beta-negative decay we have been discussing, a neutron (made from an up and two down quarks) decays into a proton (two up and a down quark) by emitting an electron and an electron-antineutrino (via the W- boson). The nucleus has not 'split' in the way you described. Some mass is converted to energy. The total mass-energy of the system is the same. It does lead to energy being eternal. If you took all the mass in the universe and converted it into energy, and added that to all the energy in the universe at the moment you would have the maximum possible amount of energy in the universe. You couldn't get any more. Convert it all to mass and you have no energy, but the most massive universe. Mass and volume are very different. For example, 100 cu. ft. of polystyrene has the same volume as 100 cu. ft. of concrete, but a very different mass. Very few people use the word "mass" where they mean "weight" - the confusion is usually the opposite way around. For example, people claim they have a "weight" of 75kg. That makes absolutely zero sense and is totally wrong. They have a mass of 75kg and a weight of approximately 736N. The word weight exists because it is a force caused by an object's surroundings, compared to mass which is a property of an object and its constituent particles. Schrödinger's cat was a thought experiment and has nothing to do with extra dimensions. It attempts to explain wavefunction collapse and the strange ideas of quantum measurements on a system.

A nucleus made of three particles (we shall ignore the electrons of the initial atom for the time being, as they play no part in this beta decay example) can't really split in the way you describe - that process simply doesn't occur, because you have to input huge amounts of energy to separate two nucleons like that. In radioactive decay the particles change, which changes the total mass and total energy of the system, but the mass-energy remains equal. In particle physics, mass is often measures in units of MeV/c2 to make the link between energy (MeV) and mass much clearer, and easier to compare. Mass and energy are equivalent, but it helps to describe them separately in examples such as this. You stated that mass was not lost in the system, which was not true, but somewhat hard to show without splitting the total mass-energy of the system into separate mass and energy components.

Haven't noticed it, but I last sent a PM a couple of days ago. I'll let you know when I send another.

On a purely technical front, I'm guessing the devices are generally booting up. When you switch them on they need to load their OS and whatever files they need to work, just like a PC. Most PCs, rather than displaying "Welcome" generally show a nice bootsplash image for you to look at. Users like visual feedback, and a long delay between turning a device on and something appearing on screen would cause people to try the power button again, turning the device off. The "Welcome" message provides fairly quick visual feedback while the rest of the information needed to run the device is loaded.On a random note, very few of my devices actually say "Hello" or "Welcome". My MP3 player shows a nice splash image for a few seconds, my digital camera pulses an LED in the power light before the screen comes on and my phone shows some random model and manufacturer information. Seems I just have unfriendly gadgets I guess

I've got an ATI card in my current PC running Kubuntu 9.10 and it works perfectly. ATI just seem to be slightly slower to release drivers, and release them for kernel and X versions that are slightly out of date, but as the versions in the Ubuntu repositories aren't usually bleeding edge, it's not that much of a problem. The newer ATI cards are also generally cooler and quieter than the equivalent nVidia card.

Not particularly. Both are releasing cards with similar performance at similar prices, so it's a matter of comparing prices at the time you buy. If you're thinking of running Linux then nVidia currently have better drivers, but ATI are catching up and improving all the time. For the HD4670, take a look here: http://forums.xisto.com/no_longer_exists/ The frame rates start on that page and go on for the next few pages. From people I've spoken to it's very hit and miss as to whether older games are working. If you're gonna switch to MicrosoftTM WindowsTM 7 then check in advance that your favourite games will work. Some are releasing patches, but older games aren't getting patches released, so you're stuck. Go with Linux from the off WINE will probably support just as many older games as MicrosoftTM WindowsTM 7.

I'm not entirely sure what you're worrying about. People could claim to be you before the forum switched to Creative Commons, so nothing has changed in that respect. The difference now is that people can quote parts of your work, but they must make it clear that you are the original author of that work. For example, when I use Creative Commons images from Flickr (currently using them on postcards) I add a line like the following to the back of the printed postcard: Image "image-name" by user-name released under the Creative Commons Attribution-Share Alike 2.0 Generic licence. (depending on the exact licence used) The same now applies to content on Xisto. People can quote it but must cite the original poster as their source, make it clear that they are the source and not mkae any claims that the work is their own, or apply any affiliation between themselves and the original author. Before the introduction of the Creative Commons licence people were not explicitly told that they had to cite the original author (although most countries laws legislate that they must). You can technically sue anyone who uses your content without citing you as the source, although I'm not sure you are that protective over it. Why would you want to delete them? Legally, people still have to cite you as the source. If anything the Creative Commons licence hammers this point home and will make people more likely to cite you as the original author than before it was introduced. In all honesty if you do find someone copying your content and not citing you then you have a few options: Send them an email/letter politely asking for the content to be removed, or adding you as the source. Contact their hosting provider and make it clear that this person is breaching copyright law. Make use of that evil piece of legislation (if you're in the US) known as the Digital Millennium Copyright Act. Speak to your solicitor. I know it sounds ridiculous, but it just as much a legal issue as someone copying articles from a newspaper and publishing them in a book without permission for example.

Let's throw some physics in here... The mass is not the same. Take beta-minus decay for example: n -> p + e- + anti-ve The mass of the neutron is 1.67492729x10-27 kg. The mass of the proton, electron and antineutrino adds up to 1.67353258x10-27 kg. So there has been a change in mass of 1.39471x10-30 kg. Where has this mass gone? Well, it hasn't gone anywhere, it has just become energy. The two are one and the same, and without that fact, you'd never be able to have beta radiation - the particles would have no source of energy to leave their parent atom so would just sit there. This energy is equal to approximately 0.785MeV, which is a sizeable amount on the atomic and nuclear scale. Gamma radiation is another good example. An electron and positron collide. They annihilate. You are left with two packages of energy and no mass. What happened to that mass? It became the energy of the gamma rays. That energy wasn't created - it was already there in the masses of the positron and electron. You are confusing a couple of concepts. The half-lives for particles such as protons and neutrons are very long because they are very stable particles (thankfully, otherwise you would have disappeared long ago...). However, in these processes energy is neither created nor destroyed - mass is energy and energy is mass. So while you are right that these particles don't last forever, energy does.

They've now appeared on your account. As other members have mentioned they only show up after you've made 5 posts in sections that award myCENTs, which you've now done. Keep making posts and when you have 100 myCENTs they'll get converted to $1 and added to your billing account so you can buy hosting and domains! I got one page to load achingly slowly, decided to not bother waiting for another page to load Yeah. The system works by matching email addresses on the forums and with billing accounts. So, if you've used the same email address for your forum account and billing account then they'll be linked. However there is a bug if you ever want to change your email address - changing it in both won't work, you'll need to send a message to support and ask them to change it.

Before the Creative Commons licence was added to the forums, all works were copyright to you and you were providing a licence to Xisto to show them on its website. Now the content is still copyright to you but people are free to use portions of it elsewhere as long as they cite you as the source - usually by providing a link back to the original location if they are reproducing it online. Therefore, by law, people have to make it clear where they got the content from and who originally created it. The same goes if people make derivations from your work. Personally I would have preferred the CC-by-nc-nd licence.

That information is usually provided by a website like Alexa and reports the traffic for that website. That information is not stored in the WHOIS database and is completely separate from domain registration information. A run down of what each term means: Rank: how popular your website is combining both number of hits and reach. 1 is the most popular, 2 the second most popular. So, in your example, that site is the 8,514,288th most popular site on the Internet (according to that data). Reach rank: expresses your rank in terms of the percentage of Internet users that visit your site, rather than the number of hits. The site that reaches the highest percentage of all Internet users is ranked 1. Page views rank: your rank in terms of page views alone. Rank 1 is the site that had the most hits, 2 is the second most hits, etc. Reach per million: out of a million people, how many people visit your site. Page views per user: fairly self explanatory - the number of pages on the site each user looks at. Alexa provide a bit more information on their ranking system at this page: http://rrchnm.org/

They did actually, as far as I know. Due to the colossal power of the PS3 it was thought people would like to run other OSs on it to take advantage of that power. Unfortunately they locked down the graphics chip, so you couldn't do a lot that required graphical power, such as playing games (otherwise people would buy a PS3 and then play games on Linux ). Plenty of people used them as PCs though, browsing the web and typing documents and the like. To stick with Sony's tradition of removing features from new versions of products rather than adding them? Because they're mean? Who knows? As far as I'm aware there was no technical reason to remove the feature, so either they were fed up with supporting it or just felt not enough people made use of it to implement it on the new slim versions.

It looks like the rumours are true. Slashdot is reporting that Apple have already completed the deal and have bought them out: http://forums.xisto.com/no_longer_exists/

On Linux all software packages downloaded from a repository are signed with a PGP key, which is used to check their authenticity. Without that key you get warnings, and you are prevented from installing the software. If the key fails, the software won't install. MD5 and SHA1 sums are also used to verify software packages not downloaded from repositories. The package and MD5/SHA1 sum are published online. You download the software and check the sum - if they match then the software hasn't been tampered with and is OK (as long as you are downloading from a reputable source).Linux is generally much better than Windows at killing processes that don't need to hang around, even if individual processes leave their children hanging around, Linux will kill them off once they're orphaned (who came up with this vocabulary?! It makes Linux seem so mean ) so that CPU power and memory aren't wasted on processes with no purpose.

KDE's System Monitor is pretty good. It's basically a visual version of the command-line "top" that shows you all of the current running processes, their CPU usage, etc. You can also get the path the program is running from, and the parent process, by hovering over each entry. Switching to "tree" view allows you to go through processes from parent to child, so you can see if one application is spawning loads more, or which application called a particular process. So, for example, I can see that Origami spawned the Folding@Home client, which spawned another two copies of itself (one for each of my CPU cores). I can also see that MySQL spawned the very vaguely named "logger" process. As for finding out what they all do (if you haven't found out already), a search engine is really the best bet and will get you more useful information than automated tools.

Just because everyone does it doesn't make it right! This is how the problems were caused when Microsoft released IE7. They finally decided to fix most of the rendering bugs from IE6 so that they actually met the W3 standards. The problem was that most web developers had totally ignored the standards and used various hacks and fixes to make their sites work specifically with IE6. The standards are there for everyone to follow - including people who code browsers. If you follow them then you are guaranteed to always have your site displayed correctly. If you use hacks and have errors then your site may work now, but not in the future. The errors on that page are caused by a single URL being encoded incorrectly I'm redesigning the site anyway, so those errors will be gone soon, but thanks for bringing them to my attention. As I've said above, following the standards is incredibly important to make sure your site displays correctly in all new browsers being released. Coding your page to the current quirks of certain versions of certain browsers is not a good idea as it makes the code a nightmare and makes it difficult to maintain. Following the standards ensures your site always displays correctly in all current and future browser versions. Of course. I was just a little short on time last night. The colours work well, especially the maroon background - it's different, but not overpowering. It could perhaps have a slight pattern or gradient to make it a bit more interesting, but it does work as it is at the moment. I would also perhaps move the text in your banner towards the bottom right hand corner, off the watch and just onto the sand. The text could also stand out a bit more from the background image. Having the entire right side bar just contain a small search box seems like a waste of space. I'd move the search box to the top of the main content area and expand its width. The sheer number of Flash elements on the page makes scrolling painful. I know Flash is an integral part of the site, but could you replace each clock with a static image, perhaps with a button to cause some Javascript to replace the image with the live clock if the user wants to see it? That would allow them to see what each clock looks like without the massive slowdown of having tons of Flash elements on one page. On a side note - all of your clocks link to your old site, and currently the link is dead. Dead links aren't good for SEO and will cause frustration to your users.

Just one thing to say: http://validator.w3.org/check?uri=http%3A%ine&group=0 Fix the errors. Once it's a valid page then we can look further at the design. Until the errors are fixed you have no idea how your site will appear in browsers!

But building it is most of the fun! If you're mainly using it for gaming you won't notice a lot of difference with a quad core over a dual core processor. The price isn't bad compared to most retail prices at the moment though. The Asus boards are pretty good for Intel processors, and should be able to handle the overclock you want on the CPU. Just beware with the watercooling that you'll have no active cooling on the motherboard heatsinks. With the overclock you're proposing that could become an issue. If I was spending this much on a PC I'd get a few SSDs rather than a traditional hard drive. Alternatively, I'd get a few hard drives and run them in a form of mirrored RAID array to protect against failure and data loss. Hard drives aren't exactly expensive and it's a worthwhile thing to do. Good choice of cards. Are you going to include them in the watercooling loop, or leave them as air cooled? Again, with your budget, it seems a shame to leave them as air cooled when you could put them in a watercooling loop. The only way to save money with the OS is to use an open-source one. Windows 7 OEM is currently over Ł140 - a rip off compared to the low low cost of Linux. I personally prefer the more subdued looks of the P183 and P193. If you do like the looks of the 900 then the 1200 is probably a better choice with your components. I've not been impressed with Apple's monitors on their current iMacs so probably wouldn't go with them for stand alone displays. As I've said before, I've been very impressed with the HP LP2475w and would thoroughly recommend it. I personally prefer my keyboards to have their buttons in the right places...

It's known as Jevons' Paradox, and is a theory in economics and business studies. It describes a vicious cycle of resource usage. As a society comes up with ways to use a resource more efficiently (such as creating energy efficient electrical goods), you lower the effective cost of using that resource to complete the same task. As the cost falls, economic demand increases, accelerating growth, which increases demand, which accelerates growth... Whether overall usage increases or decreases depends on what the ratio of cost to demand looks like. If cost falls by half, does demand increase by more than double or less than double? If demand more than doubles then you're using more energy while trying to conserve it. Until we have some way to prove them, each theory is as valid as the next. Creating a group to sift through the theories would only produce their favourite, which would not necessarily be the right one.

A scientist at the University of Utaah has decided to model climate change and the economy as a physics problem, and has come up with some startling conclusions. For example, attempting to conserve energy actually results in a net increase in energy consumption as the economy booms and energy use increases. Also, throughout history, population growth has had very little effect on energy use and climate change - energy use depends only on world economic activity. Finally, to keep CO2 levels as they are today, the world needs to build the equivalent of one nuclear power plant each and every day. The models created by this study fly in the face of current climate and economic models, so both climate scientists and economists disagree with it. The point they have the most trouble with is the idea that attempting to conserve energy simply allows the world economy to experience accelerated growth and therefore consume more energy than if you didn't try to conserve energy. However the idea isn't new - it was originally suggested in 1865, and is known as Jevons' Paradox. Studying physics, I personally find this story very interesting, as most of what we learn is based around models of what is happening in the real world. With something as difficult to track and predict as the climate, who can say which of these models is right until we already know the answer? More information: https://www.sciencedaily.com/releases/2009/91123083704.htm

At the most basic level, you'll need to install PHP: http://php.net/downloads.php That will allow you to run PHP scripts from the command line. However, most people want to also set up a web server at the same time, to run on their PC and try their scripts out without using the command line. For that, I recommend Apache's HTTP Server: http://httpd.apache.org/download.cgi If you're writing more complex PHP scripts, you'll likely end up needing a database to store data. PHP includes SQLite, but most people opt for MySQL Community Server, which you can get here: http://dev.mysql.com/downloads/mysql/5.1.html Installing those will give you a fully functioning environment to try out your PHP applications. There are also pieces of software that will install all of those for you, although I tend not to use them. One of the most popular is XAMPP if you want to give that a try: https://www.apachefriends.org/index.html

Like anwiii has said, it's not really your decision. You may want your son to go to a prestigious university, but he may not want to do that. The fact you say he doesn't like attending school and studying certainly makes me think that a good university is not top of his list of life goals. You'll need to talk to him and work out exactly where he wants to go with his life. If he has an ideal job then work back from that - find out if a degree is needed, what other training, and then he can plan his education to follow that path. If he's not sure yet then let him go with what he enjoys. He will work best at things he enjoys, and they are more likely to be the degrees he'd like to do if he goes to university. Most high schools should also offer him careers advice and information on getting in to university if that is what interests him.