I hope Mr. Brown is getting compensated well, because he's soon going to find that's he's completely destroyed his career. I seriously doubt that anyone will wish to obtain his services after this fiasco.
Aside from relativity considerations for KE, I'm not sure what you are referring to that is "incorrect". The link you mentioned seems blatantly in error by stating that "F=mV2" (by which I assume they mean F=mv^2), simply because the units do not match on both sides of the equation: "F" is kg*m/s^2 which is Newtons (force), while "mv^2" is kg*m^2/s^2 which is Joules (energy). I imagine it is a typographic error of some sort?
It's not a typographic error. Many people really have been taught that F=mv2 instead of F=ma or F=(mv2)/r. And that's my point. If you look around, you'll find all kinds of people using the incorrect formula of F=mv2.
If we are to include relativistic considerations then, we must begin with the full equation:
E = (mc^2)*(1-(v/c)^2)^-1/2
You can't include relativistic considerations in E=mc2, because the speed of light is the only constant, regardless of your point of observation. I can go faster, and light will still travel 300,000 km per second. I can slow down and light will travel at 300,000 km per second. I can cross from one end of the universe to the other in 10 seconds (millions of years Earth time) and still see that light is traveling at 300,000 km per second faster than I am. No object in the universe can ever travel so fast as to begin to "catch up" with light. (From its own perspective, that it.)
Einstein originally called Relativity, "The Theory of Invariants" because light speed was absolutely invariant.
I once read something similar to this which basically argued that everything travels at the speed of light, and it explained slower objects as actually traveling at a high speed in other dimensions (of which we are unaware) such that the sum of these vectors has a magnitude of c. I suppose it's possible, but I didn't know that that was what Einstein was saying. Of course, I'm just a novice at this point.
That's exactly what he was saying.:-) If you haven't read Brian Green's "Elegant Universe", I might suggest you start there. Also:
You have to remember that "time" as we think of it, is merely our interpretation of another dimension. In order to understand it, let's pretend we're in a two dimensional universe with a third dimension of time. Here's the path of two cars along the X/Y axis (X is left/right, y is up/down):
0----> 0---->
Which one traveled father? In a two dimensional universe, you'd say that they traveled the same distance. But then comes our third dimension that our fictional inhabitants perceive as "time". Here's a cross section of their X/Z axis (X is left and right, Z is up and down):
0----->
>
0
(Please forgive the lack of a line of the second item. Slashdot ate my ASCII art. Just pretend there's a line between the '0' and '>'.
Now which one drove farther? If you said the second one, you're correct. The second one, "took his time". He was traveling at an angle through the third dimension (Z) and thus traveled farther to reach the same destination.
If you understand the above, you should now understand time dilation. If I travel faster through the first three dimension of "space" (as our first car did), I would travel slower through the forth dimension of "space" that we perceive as "time". Thus time would appear to "slow down" as I go faster. But how does this explain light being invariable?
Ok, let's assume for a moment that the first car above represents a photon, and the second car represents an object occupying our universe. The second object has a vector that always tilts (at least some) in the direction of time. That allows the object to perceive time. But the second object only travels on the X/Y plane. This means that from its perspective, it wil
With high enough doses, I can see that. But I was wondering if in smaller doses, which may seem to have little to no effect, there actually are non-fatal effects such as the more subtle symptoms I mentioned.
I'm not a doctor, so take this with a grain of salt. But what I'm trying to get at is that your body routes around toxins and foreign particles all the time. As long as these particles are insufficient to interfere with your body's chemical operations, its presence should make no difference. The radiological effects add a new wrinkle, because even in super small quantities, they can potentially cause damage to your body's structure. For example, you only need to inhale 20 milligrams of Pu-238 to guarantee death within one month. Portions less than that simply increase the risk of cancer. It's even possible that 1/10 milligram could cause cancer. It's just not as likely.
Now in the grand scheme of things, a few milligrams of nearly anything is insufficient to impact your body in any serious manner. Materials of that toxicity usually impair something very specific and vulnerable such as the nervous system. Most of the radioisotopes I'm aware of don't fall into this category, but are instead classified as heavy metals. Radioisotopes of non-metallic nature (e.g. Iodine) behave exactly as their non-radioactive counterparts.
That is sad if your high school physics taught that... IIRC, 0.5*mv^2 = kinetic energy, not force.
High school physics have long taught this little gem. It's too bad it's incorrect. Not to mention that many people don't know that it's incorrect. For example, a quick googling comes up with links like this one.
The bright side is that most of today's high schools seem to have switched their physics textbooks to newer and more correct ones. Too bad for those of us before the change.:-(
BTW, one thing I did notice when I learned the correct formula:
Kinetic Energy = (mv2)/2
"Every action has an opposite and equal reaction", therefore
Total Energy in a System = mv2
"As an object approaches the speed of light, its mass grows to infinity", therefore
E=mc2
I was pretty proud of myself for that one.:-)
Or did you mean F=ma and you're referring to the insufficiencies of the Newtonian model? I think that the Newtonian model is only significantly false at near light velocities (and therefore quite useful for many cases), at which point the relativistic mass changes wrt direction. i.e. it becomes more difficult to accelerate in the same direction as its current velocity, but not in orthogonal directions (relativistic mass is directional!).
It's not directional, it's dimensional! You see, Einstein explained that everything in the Universe has a "velocity" of light speed. Now everyone knows that you can go West fastest by travelling due west, and south fastest by going due south. But if you travel in a south-westernly direction, you'll go slower toward each point of reference. Now if we apply this to dimensions, an object at complete rest in our universe is going infinitely fast through time. An object traveling at light speed is a perfect rest through the fourth dimension. And guess what? We can even see this effect!
Let's say for a moment that I have two horizontal panels with a ball bouncing vertically between them. If I move the panels, the the ball will "miss" them completely. And yet, I can perform this experiment on a train and be able to watch the ball bounce straight up and down. If we were to pretend that the train didn't exist, what might an observer on the ground see as the panels and ball passed by him? He'd probably notice that the ball is actually bouncing at a slight angle to "catch" the panels.
Now let's assume that the ball bounces back and forth 10 times a second. Let's put a set of panels on a spaceship traveling at 90% c. Re
Duh... I dont know.. I guess all your photos and video files come pre-pressed on the PROMS insode the unit... duh....
boot up steps....
boot, get dhcp lease, find shares, look in shares and create a catalogue of media there, present the UI.
There's a reason why God created directory structures.
if you are a complete and utter idiot and shared your entire C drive instead of the exact directory that holds your media it can take almost 10 minutes to find all media and catalogue it.
What the hell is so hard for you to understand?
The fact that he didn't say this in the article? He said it took a minute or so to boot up the first time he turned it on. All the software should be in the PROM, and the disk should have been relatively empty. Even if it wasn't, the indexes should have made the operation only a few microseconds.
It's called software engineering. Believe it or not, It works.
Which, by itself, wouldn't have been a *bad* thing provided you didn't install EVERY freaking library and application that came on the install media.
No, it's not. An OS like Linux can be made to boot super-fast by properly tuning the system, and preloading everything into ROM memory space. Since no disk access is necessary when the device is turned on (remember, it's already in memory), only a quick initialization procedure should occur.
I'd have to disagree on this point as a TiVo owner. TiVo implements upgrades to their OS every once in awhile, and that includes when patches and new driver updates for Linux are made available. Thus indirectly to the user, Linux is a feature of the TiVo platform.
No, it's a feature to the manufacturer. If the manufacturer had built a custom OS, they would be responsible for maintenance and patches of that OS. Basing it on Linux or BSD allows them to rely on others for those services. The only "feature" is that the device is cheaper to the consumer.
With everything connected, I hit the On button and the unit began booting up, just like a computer, and after about a minute, it was ready to go -- not exactly instant-on.
These people need to understand, Linux is NOT a feature! In a device like this, the OS (whatever it is) should be as transparent to the user as possible. The only person the OS should make a difference to is the manufacturer. Using Linux or BSD should allow them to pull "off the shelf" software in the same way they build it with "off the shelf" hardware. Instead, it sounds like they took Fedora or something and crammed it into a consumer device.
If we can get people to accept commercial use of radioactive isotopes, would they be cost effective?
Not in the short term. However, power sources like Pu-238 oxide last for a very long time. (~80 year half life.) This allows for a refurbishment of the materials every few years, thus reducing the costs considerably. e.g. If one was to plan for a 10 year lease on these batteries, the initial cost could be spread over that time. After the battery is returned, the Pu-238 can be purified and the lost quantity replaced. Given an example of 600 grams of Pu-238, only 75 grams would need to be replaced after 10 years.
If the proper isotopes can be obtained cheaply, could they be used for winter house heating in the north? In spring, you could just move some baffles to vent the unwanted heat outside.
Difficult question. Heating all comes down to the wattage expended in heating the alcove. If less than 1 KW is sufficient to heat a station, then radioisotopes could be viable. If the energy requirements are in the multi-kilowatt range, a traditional method would probably be more effective.
In addition to the type of radiation, I imagine chemical reactions with the substances themselves must also be taken into account, as you indicate with the use of Sr-90 for Ca and I isotopes for stable I.
From what I know (which is admittedly not as much as a full nuclear physicist or a doctor trained in nuclear medicine), the actual chemical properties of most radioisotopes are not a major concern. It's certainly possible to get heavy metal poisoning from plutonium or uranium, but in practice the radiological consequences would kill you long before you saw any chemical effects. The EPA has fact sheets on all radioisotopes. Not to mention that MSDS should be available for those same materials.
One thing to keep in mind is that most isotopes do not have significantly different chemical properties than their non-isotope forms.
I thought an alpha particle was a helium nucleus (2p,2n)... though maybe you meant that it simply behaves somewhat similarly to a single proton? I don't thinks so, but I don't really know.
I'm sorry, I misspoke. You are correct. Alpha radiation consists of ionized helium particles. I'm still trying to evacuate some of high school "physics" that exists in my brain. (Did you know that force != mv2? Grr... Stupid high school physics.)
As I understand it, the thyroid absorbs Iodine, so ingesting stable Iodine will take the place of the radioactive Iodine in the thyroid, and when the thyroid is at capacity, the excess Iodine can be excreted.
Correct. That's why many of the Chernobyl victims were children who hadn't yet built up enough iodine in their system. The dangers from radioactive iodine would be far lower for the American (and European?) population due to our practice of fortifying salt with Iodine.
It's interesting that continued treatment is required, perhaps to further dilute any remaining bad Iodine? It's also interesting since I thought Iodine isotopes had a relatively short lifetime?
The treatment (AFAIK) is for the cancer. There's a certain hormone that must be taken in order to replace the Thyroid's function. As usual, Wikipedia has more info.
Someone once told me that radioactive Iodine could be created by striking stable Iodine (within the human body) with x-ray radiation, but I thought a neutron was required to strike the nucleus for such a modification; unless the x-ray can trigger the release of a neutron from some other molecules in the body? Any thoughts?
There's something called "nuclear remediation" which uses X-Ray pulses to knock a neutron free from a nucleus. The purpose of this process is to make a radioisotope less stable, and therefore reduce its half-life. If the half-life can be reduced to seconds, hours, or even a few months, it can simply be stored until a more stable element emerges.
I don't think we really understand why it works, but I think the theory is that when the massive amount of energy is absorbed from the X-Ray "photon", the nucleus becomes less stable. The protons and electrons are held in place by electromagnetic charges, so the energy is transferred to a neutron instead. Obviously, the loss of the neutron results in a weaker overall structure for the nucleus, and it begins to convert its excess matter into radiation.
Actually, the intent of my previous post was to question whether more subtle chronic problems could arise from smaller quantities of these heavy metals or radioisotopes, whether that be a lowered immunity, reduced nutrient absorption (Sr-90 in place of Ca?), or even general symptoms such as lethargy, depression, chronic pain, nerve damage, or other neurological deficiencies.
As I said, the chemical properties of these elements does not change much, and in practice the radiological effects are far more pronounced than any chemical issues.
I'm no expert in nuclear materials, but wouldn't holding anything radioactive enough to feel hot kill you rather quickly?
Pu-238 primarily emits Alpha particles. The heat that you feel is from the Alpha radiation being blocked. By what you ask? Just about everything. Alpha particles can't penetrate a sheet of paper, much less your skin or even the rest of the plutonium.
Umm... you didn't draw a Stirling engine my friend. Seems you have a hole in it! In your drawing, your exhaust hole will not only bleed out heat(T), but it will bleed out the air itself (n).
I've long lost the link, but I had based it on a open air design I saw somewhere. The idea being that the piston would pass the exhaust port on the way up. When the exhaust port is reached, a heat and air exchange would occur. In the design I saw, gravity was supposed to bring the piston back down to compress the gas. Hmmm... oh well. If it doesn't work, time to move on to the next design.:-)
I also have a problem with your heat source, because it's not a heat source, but a radiation source.
It is a radiation source, but the radiation is converted to heat as it strikes the walls of its container. If you hold a rock of Pu-238 in your hand, you'll find that it's quite warm. In fact, Pu-238 gives off sufficient heat to boil water.
This will be even less reliable than a gas burner when it comes to regulating production, because you added even more time to the heat transfer process
You wouldn't want to regulate production. The radiation is predictable enough to where it should produce a constant level of heat. This heat can be used to create the same amount of power, non stop. If the battery begins to overcharge, the device would need to bleed off the extra energy in either a small heating coil or a mechanical source such as a fan.
Thanks for your help! I'll ponder this a bit and maybe produce a more viable design. Maybe one day I'll even find a way to build a prototype.:-)
My concern is not only the mortal effects of heavy metals or radioactive substances, but also any chronic problems created by or exasperated by such substances.
I might suggest bolstering what I say here with some research on the Internet, but the Health effects of radioisotopes break down by the type of radiation they release.
Alpha particles are basically free protons. They have very little penetration power and can be shielded against by a sheet of paper or your layer of dead skin cells. It's slow movement and low penetration power does make it dangerous if inhaled or rubbed into an open wound, however. Whereas a more energetic particle might completely miss all the matter (or at least important matter) in your body, an Alpha particle has more time to make a critical severing of a DNA or RNA strand. In small quantities the effects aren't a big deal, but inhaled into the soft tissue of the lungs results in a large number of alpha particles getting the chance to do damage. Plutonium is generally an Alpha emitter, but is very rarely machined into a fine powder.
Beta particles are basically free electrons and share a lot of properties with electricity. (In fact they are very similar to a cathode ray.) A certain voltaic pressure is necessary to penetrate the skin, but Beta particles do have somewhat more penetration power than Alpha particles. Sr-90 is a common beta emitter that is chemically similar to Calcium. As a result it can end up being deposited in the bones where it can do damage to the sensitive marrow. A certain amount of Sr-90 is already in the biosphere from the thousands of nuclear tests during the 50's and 60's. The EPA has more info on this, but the levels are not considered dangerous.
Gamma and X-Ray radiation are high frequency radio waves with a high power of penetration. In high enough concentrations they can fry you as surely as a microwave beam. In small amounts they tend to pass directly through your body without interfering. Gamma and X-Rays are common in background radiation and have often been emitted by poor electronics in previous years. (e.g. televisions) Gamma and X-Rays are generally considered the most dangerous as they can have far more effects on your body at an external level.
Neutron radiation is a release of free neutron particles. These particles are so heavy that you can expect them to destroy just about any material in existence. A certain number of these particles is required to sustain nuclear fission. In nuclear fusion, the neutron flux is so strong that it tends to cause the reactor casing to fall apart. (This has been one of the biggest difficulties in fusion research.)
So what does all this add up to? Well, don't eat any extra Sr-90 you find lying around, don't machine any plutonium, and don't stand next to an unshielded nuclear reactor. Keep those three things in mind and you should be just fine.;-)
Oh, and anyone who doesn't get enough Iodine in their diet shouldn't eat an Iodine radioisotope. That tends to result in Thyroid cancer as in the case of many Chernobyl residents. Most of them were treated, but they still have to make sure they receive regular treatments or they will die.
Yeah "quite a bugs" like erasing your whole User folder when you try to use the Java.net.* classes.
Err... quite a few bugs. Can't say I've seen it erase any folders, though. Should I ask why you have a link to some game site, or should I just tell moderators to mark you as -1 Troll?
...he mentioned Java because there's a Bridge mechanism in OS X that allows Java code to call ObjC code, and ObjC code to call Java code. I've used it myself and found it to be an effective way to write Java programs that are native to the OS X platform. Be warned, however. Differences in the way ObjC and Java handle objects causes quite a bugs. Not everything can be 100% mapped, so you'll find yourself writing some ObjC anyway.
If it helps any, I agree perfectly well. People seem to feel the need to think that humans are not ingenuitive enough to develop stuff on our own. They say stuff like "the Egyptians lifted 300 ton block! We can't even do that today!" At which point I have to point out the Space Shuttle crane, or lifting a 1000 foot ship into drydock. Then I start mentioning technologies like RamJets, Nuclear Thermal Propulsion, and others that had always been considered nothing more than Sci-Fi.
We actually have a lot more tech at our fingertips than we're using today. We're not using it because there's no push to develop it. Not to mention to push to "make everything safer" and round all the corners. Bah.
On the other hand, I'm far more concerned about consumer-portable SRG slowly contaminating the water supply after being tossed into a dump much like NiCds are doing today.
This is less of a concern for two reasons. One, the materials would tend to settle in the sediment and become harmless. Both the sediment and the water would provide excellent radiation protection. Remember that Alpha particles (the primary radioparticle released by Pu-238) is easily blocked by a sheet of paper. Your dead skin layer does an even better job.
Oh, and there's *cough* already radioisotopes in your food and water thanks to *cough* nuclear testing in the 50's and 60's.
The one other reason was that my plan called for leasing the devices instead of selling them outright. By leasing them, they could be recovered, refurbished, and even be used to create new (and cheaper) batteries.
I was going to complain than an SRG is way too heavy, but some digging found that a 55 W SRG prototype was only about 27 kg. Not really man-portable for infantry purposes, but infantry electronics are designed for lower power usage, so a smaller one could be created.
No need for a smaller one. Most of the weight in RTGs and SRGs are from the graphite shielding that's used to protect the device during an uncontrolled reentry into the atmosphere. Since an infantry device would be intended for ground use, it would only need to weigh a kilos or two.
Now for vehicles, you might have something there -- just not for civillian cars, in my opinion.
Not enough energy. You need several kilowatts of power to cruise a vehicle at 60 MPH. Accelerating results in a temporary usage of 10's of kilowatts of power. In case you're interested, it takes ~745 Watts to produce one horsepower of drive.
It began flying in December, 1964. However, it had already been announced by President Johnson in February of 1964! It was in this speech that the President "accidentally" switched the name from RS-71 to SR-71. A little more digging shows that the USAF Chief of Staff had intentionally switched the letters in the President's speech because he liked SR-71 better than RS-71.
B When did they start flying the "Stealth Bomber"?
Similarly, the B-2 bomber was on public display on November 22, 1988, but its first flight wasn't until July 17, 1989. The final product wasn't delivered until 1993, and it didn't see combat until 1999.
Allow me to reiterate my previous point. The government is lousy at keeping secrets! And with this constant Myth of an Aurora out there somewhere, the government would have an extremely difficult time keeping such a craft under wraps. They'd be far more likely to just announce its existence and get it over with. It's not like they'd tell the public anything useful anyway. They'd simply confirm or deny the craft's propulsion method, stealth features, and approximate cruising speed. It's real ceiling of operation would remain classified until it went out of service.
For the very first stoke this will work fine, but after the pressure escapes through the exhaust port. The remaining air in the cylinder is still heated so you will no longer get any thermal expansion from that same air.
Hmm... I thought that air-cooled Stirling engines worked because the heat would attempt to equalized the temperature inside the cylinder and outside in the open air. Perhaps I was incorrect. Many Stirling designs actually call for some sort of active cooling. NASA uses cycled helium for this purpose.
This is assuming you're not using some spring or relying on the momentum of the shaft somehow.
I was planning that the momentum would be sufficient to keep the device running. However, I have also been concerned about this problem. My alternate design actually has two "half-size" pistons connected to the dynamo. When one goes up, it forces the other one down. It may even make sense to offset the drive shaft such that one piston will finish moving the other piston up (thus exposing more of an air exchange outlet) before driving it back down.
Just my non-expert two cents.
It's more feedback then I ever got from the "experts" on the energy newsgroups.:-)
No, thank you. Sometimes I feel like I'm just beating my head against a wall instead of actually educating anyone. Your response gives me heart that people *are* listening.:-)
In 1985 you might be able to get plutonium from your local corner store, but here in 2004 it's a little harder to come by!
Ok, now THAT was a great joke. Mod parent up as funny!
BTW, I should probably use this opportunity to point out that different forms of Plutonium exist. Pu-239 is useful for bombs and reactors because it easily fissions. However, it has far too long of a half-life to be useful for RTGs and SRGs. Pu-238 OTOH, is great for RTGs and SRGs, but is absolutely useless as a fissionable material.
Slashdot Mirror
I hope Mr. Brown is getting compensated well, because he's soon going to find that's he's completely destroyed his career. I seriously doubt that anyone will wish to obtain his services after this fiasco.
It's not a typographic error. Many people really have been taught that F=mv2 instead of F=ma or F=(mv2)/r. And that's my point. If you look around, you'll find all kinds of people using the incorrect formula of F=mv2.
If we are to include relativistic considerations then, we must begin with the full equation:
E = (mc^2)*(1-(v/c)^2)^-1/2
You can't include relativistic considerations in E=mc2, because the speed of light is the only constant, regardless of your point of observation. I can go faster, and light will still travel 300,000 km per second. I can slow down and light will travel at 300,000 km per second. I can cross from one end of the universe to the other in 10 seconds (millions of years Earth time) and still see that light is traveling at 300,000 km per second faster than I am. No object in the universe can ever travel so fast as to begin to "catch up" with light. (From its own perspective, that it.)
Einstein originally called Relativity, "The Theory of Invariants" because light speed was absolutely invariant.
I once read something similar to this which basically argued that everything travels at the speed of light, and it explained slower objects as actually traveling at a high speed in other dimensions (of which we are unaware) such that the sum of these vectors has a magnitude of c. I suppose it's possible, but I didn't know that that was what Einstein was saying. Of course, I'm just a novice at this point.
That's exactly what he was saying.
Wikipedia
C-Ship Thought Experiment
You have to remember that "time" as we think of it, is merely our interpretation of another dimension. In order to understand it, let's pretend we're in a two dimensional universe with a third dimension of time. Here's the path of two cars along the X/Y axis (X is left/right, y is up/down):
Which one traveled father? In a two dimensional universe, you'd say that they traveled the same distance. But then comes our third dimension that our fictional inhabitants perceive as "time". Here's a cross section of their X/Z axis (X is left and right, Z is up and down):
(Please forgive the lack of a line of the second item. Slashdot ate my ASCII art. Just pretend there's a line between the '0' and '>'.
Now which one drove farther? If you said the second one, you're correct. The second one, "took his time". He was traveling at an angle through the third dimension (Z) and thus traveled farther to reach the same destination.
If you understand the above, you should now understand time dilation. If I travel faster through the first three dimension of "space" (as our first car did), I would travel slower through the forth dimension of "space" that we perceive as "time". Thus time would appear to "slow down" as I go faster. But how does this explain light being invariable?
Ok, let's assume for a moment that the first car above represents a photon, and the second car represents an object occupying our universe. The second object has a vector that always tilts (at least some) in the direction of time. That allows the object to perceive time. But the second object only travels on the X/Y plane. This means that from its perspective, it wil
With high enough doses, I can see that. But I was wondering if in smaller doses, which may seem to have little to no effect, there actually are non-fatal effects such as the more subtle symptoms I mentioned.
:-(
:-)
I'm not a doctor, so take this with a grain of salt. But what I'm trying to get at is that your body routes around toxins and foreign particles all the time. As long as these particles are insufficient to interfere with your body's chemical operations, its presence should make no difference. The radiological effects add a new wrinkle, because even in super small quantities, they can potentially cause damage to your body's structure. For example, you only need to inhale 20 milligrams of Pu-238 to guarantee death within one month. Portions less than that simply increase the risk of cancer. It's even possible that 1/10 milligram could cause cancer. It's just not as likely.
Now in the grand scheme of things, a few milligrams of nearly anything is insufficient to impact your body in any serious manner. Materials of that toxicity usually impair something very specific and vulnerable such as the nervous system. Most of the radioisotopes I'm aware of don't fall into this category, but are instead classified as heavy metals. Radioisotopes of non-metallic nature (e.g. Iodine) behave exactly as their non-radioactive counterparts.
That is sad if your high school physics taught that... IIRC, 0.5*mv^2 = kinetic energy, not force.
High school physics have long taught this little gem. It's too bad it's incorrect. Not to mention that many people don't know that it's incorrect. For example, a quick googling comes up with links like this one.
The bright side is that most of today's high schools seem to have switched their physics textbooks to newer and more correct ones. Too bad for those of us before the change.
BTW, one thing I did notice when I learned the correct formula:
Kinetic Energy = (mv2)/2
"Every action has an opposite and equal reaction", therefore
Total Energy in a System = mv2
"As an object approaches the speed of light, its mass grows to infinity", therefore
E=mc2
I was pretty proud of myself for that one.
Or did you mean F=ma and you're referring to the insufficiencies of the Newtonian model? I think that the Newtonian model is only significantly false at near light velocities (and therefore quite useful for many cases), at which point the relativistic mass changes wrt direction. i.e. it becomes more difficult to accelerate in the same direction as its current velocity, but not in orthogonal directions (relativistic mass is directional!).
It's not directional, it's dimensional! You see, Einstein explained that everything in the Universe has a "velocity" of light speed. Now everyone knows that you can go West fastest by travelling due west, and south fastest by going due south. But if you travel in a south-westernly direction, you'll go slower toward each point of reference. Now if we apply this to dimensions, an object at complete rest in our universe is going infinitely fast through time. An object traveling at light speed is a perfect rest through the fourth dimension. And guess what? We can even see this effect!
Let's say for a moment that I have two horizontal panels with a ball bouncing vertically between them. If I move the panels, the the ball will "miss" them completely. And yet, I can perform this experiment on a train and be able to watch the ball bounce straight up and down. If we were to pretend that the train didn't exist, what might an observer on the ground see as the panels and ball passed by him? He'd probably notice that the ball is actually bouncing at a slight angle to "catch" the panels.
Now let's assume that the ball bounces back and forth 10 times a second. Let's put a set of panels on a spaceship traveling at 90% c. Re
Duh... I dont know.. I guess all your photos and video files come pre-pressed on the PROMS insode the unit... duh....
boot up steps....
boot, get dhcp lease, find shares, look in shares and create a catalogue of media there, present the UI.
There's a reason why God created directory structures.
if you are a complete and utter idiot and shared your entire C drive instead of the exact directory that holds your media it can take almost 10 minutes to find all media and catalogue it.
What the hell is so hard for you to understand?
The fact that he didn't say this in the article? He said it took a minute or so to boot up the first time he turned it on. All the software should be in the PROM, and the disk should have been relatively empty. Even if it wasn't, the indexes should have made the operation only a few microseconds.
It's called software engineering. Believe it or not, It works.
Sorry, that first sentence should read "No, it's not a good thing."
hello why does this device require to defy laws of physics?
it will TAKE A LONG TIME to go through your shares you are pointing at it. espically if you were a dolt and simply shared the entire C drive.
What the hell are you talking about?
Which, by itself, wouldn't have been a *bad* thing provided you didn't install EVERY freaking library and application that came on the install media.
No, it's not. An OS like Linux can be made to boot super-fast by properly tuning the system, and preloading everything into ROM memory space. Since no disk access is necessary when the device is turned on (remember, it's already in memory), only a quick initialization procedure should occur.
I'd have to disagree on this point as a TiVo owner. TiVo implements upgrades to their OS every once in awhile, and that includes when patches and new driver updates for Linux are made available. Thus indirectly to the user, Linux is a feature of the TiVo platform.
No, it's a feature to the manufacturer. If the manufacturer had built a custom OS, they would be responsible for maintenance and patches of that OS. Basing it on Linux or BSD allows them to rely on others for those services. The only "feature" is that the device is cheaper to the consumer.
Not to mention...
With everything connected, I hit the On button and the unit began booting up, just like a computer, and after about a minute, it was ready to go -- not exactly instant-on.
These people need to understand, Linux is NOT a feature! In a device like this, the OS (whatever it is) should be as transparent to the user as possible. The only person the OS should make a difference to is the manufacturer. Using Linux or BSD should allow them to pull "off the shelf" software in the same way they build it with "off the shelf" hardware. Instead, it sounds like they took Fedora or something and crammed it into a consumer device.
If we can get people to accept commercial use of radioactive isotopes, would they be cost effective?
Not in the short term. However, power sources like Pu-238 oxide last for a very long time. (~80 year half life.) This allows for a refurbishment of the materials every few years, thus reducing the costs considerably. e.g. If one was to plan for a 10 year lease on these batteries, the initial cost could be spread over that time. After the battery is returned, the Pu-238 can be purified and the lost quantity replaced. Given an example of 600 grams of Pu-238, only 75 grams would need to be replaced after 10 years.
If the proper isotopes can be obtained cheaply, could they be used for winter house heating in the north? In spring, you could just move some baffles to vent the unwanted heat outside.
Difficult question. Heating all comes down to the wattage expended in heating the alcove. If less than 1 KW is sufficient to heat a station, then radioisotopes could be viable. If the energy requirements are in the multi-kilowatt range, a traditional method would probably be more effective.
In addition to the type of radiation, I imagine chemical reactions with the substances themselves must also be taken into account, as you indicate with the use of Sr-90 for Ca and I isotopes for stable I.
:-)
From what I know (which is admittedly not as much as a full nuclear physicist or a doctor trained in nuclear medicine), the actual chemical properties of most radioisotopes are not a major concern. It's certainly possible to get heavy metal poisoning from plutonium or uranium, but in practice the radiological consequences would kill you long before you saw any chemical effects. The EPA has fact sheets on all radioisotopes. Not to mention that MSDS should be available for those same materials.
One thing to keep in mind is that most isotopes do not have significantly different chemical properties than their non-isotope forms.
I thought an alpha particle was a helium nucleus (2p,2n)... though maybe you meant that it simply behaves somewhat similarly to a single proton? I don't thinks so, but I don't really know.
I'm sorry, I misspoke. You are correct. Alpha radiation consists of ionized helium particles. I'm still trying to evacuate some of high school "physics" that exists in my brain. (Did you know that force != mv2? Grr... Stupid high school physics.)
As I understand it, the thyroid absorbs Iodine, so ingesting stable Iodine will take the place of the radioactive Iodine in the thyroid, and when the thyroid is at capacity, the excess Iodine can be excreted.
Correct. That's why many of the Chernobyl victims were children who hadn't yet built up enough iodine in their system. The dangers from radioactive iodine would be far lower for the American (and European?) population due to our practice of fortifying salt with Iodine.
It's interesting that continued treatment is required, perhaps to further dilute any remaining bad Iodine? It's also interesting since I thought Iodine isotopes had a relatively short lifetime?
The treatment (AFAIK) is for the cancer. There's a certain hormone that must be taken in order to replace the Thyroid's function. As usual, Wikipedia has more info.
Someone once told me that radioactive Iodine could be created by striking stable Iodine (within the human body) with x-ray radiation, but I thought a neutron was required to strike the nucleus for such a modification; unless the x-ray can trigger the release of a neutron from some other molecules in the body? Any thoughts?
There's something called "nuclear remediation" which uses X-Ray pulses to knock a neutron free from a nucleus. The purpose of this process is to make a radioisotope less stable, and therefore reduce its half-life. If the half-life can be reduced to seconds, hours, or even a few months, it can simply be stored until a more stable element emerges.
I don't think we really understand why it works, but I think the theory is that when the massive amount of energy is absorbed from the X-Ray "photon", the nucleus becomes less stable. The protons and electrons are held in place by electromagnetic charges, so the energy is transferred to a neutron instead. Obviously, the loss of the neutron results in a weaker overall structure for the nucleus, and it begins to convert its excess matter into radiation.
Actually, the intent of my previous post was to question whether more subtle chronic problems could arise from smaller quantities of these heavy metals or radioisotopes, whether that be a lowered immunity, reduced nutrient absorption (Sr-90 in place of Ca?), or even general symptoms such as lethargy, depression, chronic pain, nerve damage, or other neurological deficiencies.
As I said, the chemical properties of these elements does not change much, and in practice the radiological effects are far more pronounced than any chemical issues.
Thanks again for your excellent posts.
You're most welcome.
I'm no expert in nuclear materials, but wouldn't holding anything radioactive enough to feel hot kill you rather quickly?
Pu-238 primarily emits Alpha particles. The heat that you feel is from the Alpha radiation being blocked. By what you ask? Just about everything. Alpha particles can't penetrate a sheet of paper, much less your skin or even the rest of the plutonium.
If I understand correctly, the compiler generates "glue" code at compile time. This makes it (almost) completely transparent to the programmer.
Umm... you didn't draw a Stirling engine my friend. Seems you have a hole in it! In your drawing, your exhaust hole will not only bleed out heat(T), but it will bleed out the air itself (n).
:-)
:-)
I've long lost the link, but I had based it on a open air design I saw somewhere. The idea being that the piston would pass the exhaust port on the way up. When the exhaust port is reached, a heat and air exchange would occur. In the design I saw, gravity was supposed to bring the piston back down to compress the gas. Hmmm... oh well. If it doesn't work, time to move on to the next design.
I also have a problem with your heat source, because it's not a heat source, but a radiation source.
It is a radiation source, but the radiation is converted to heat as it strikes the walls of its container. If you hold a rock of Pu-238 in your hand, you'll find that it's quite warm. In fact, Pu-238 gives off sufficient heat to boil water.
This will be even less reliable than a gas burner when it comes to regulating production, because you added even more time to the heat transfer process
You wouldn't want to regulate production. The radiation is predictable enough to where it should produce a constant level of heat. This heat can be used to create the same amount of power, non stop. If the battery begins to overcharge, the device would need to bleed off the extra energy in either a small heating coil or a mechanical source such as a fan.
Thanks for your help! I'll ponder this a bit and maybe produce a more viable design. Maybe one day I'll even find a way to build a prototype.
My concern is not only the mortal effects of heavy metals or radioactive substances, but also any chronic problems created by or exasperated by such substances.
;-)
I might suggest bolstering what I say here with some research on the Internet, but the Health effects of radioisotopes break down by the type of radiation they release.
Alpha particles are basically free protons. They have very little penetration power and can be shielded against by a sheet of paper or your layer of dead skin cells. It's slow movement and low penetration power does make it dangerous if inhaled or rubbed into an open wound, however. Whereas a more energetic particle might completely miss all the matter (or at least important matter) in your body, an Alpha particle has more time to make a critical severing of a DNA or RNA strand. In small quantities the effects aren't a big deal, but inhaled into the soft tissue of the lungs results in a large number of alpha particles getting the chance to do damage. Plutonium is generally an Alpha emitter, but is very rarely machined into a fine powder.
Beta particles are basically free electrons and share a lot of properties with electricity. (In fact they are very similar to a cathode ray.) A certain voltaic pressure is necessary to penetrate the skin, but Beta particles do have somewhat more penetration power than Alpha particles. Sr-90 is a common beta emitter that is chemically similar to Calcium. As a result it can end up being deposited in the bones where it can do damage to the sensitive marrow. A certain amount of Sr-90 is already in the biosphere from the thousands of nuclear tests during the 50's and 60's. The EPA has more info on this, but the levels are not considered dangerous.
Gamma and X-Ray radiation are high frequency radio waves with a high power of penetration. In high enough concentrations they can fry you as surely as a microwave beam. In small amounts they tend to pass directly through your body without interfering. Gamma and X-Rays are common in background radiation and have often been emitted by poor electronics in previous years. (e.g. televisions) Gamma and X-Rays are generally considered the most dangerous as they can have far more effects on your body at an external level.
Neutron radiation is a release of free neutron particles. These particles are so heavy that you can expect them to destroy just about any material in existence. A certain number of these particles is required to sustain nuclear fission. In nuclear fusion, the neutron flux is so strong that it tends to cause the reactor casing to fall apart. (This has been one of the biggest difficulties in fusion research.)
So what does all this add up to? Well, don't eat any extra Sr-90 you find lying around, don't machine any plutonium, and don't stand next to an unshielded nuclear reactor. Keep those three things in mind and you should be just fine.
Oh, and anyone who doesn't get enough Iodine in their diet shouldn't eat an Iodine radioisotope. That tends to result in Thyroid cancer as in the case of many Chernobyl residents. Most of them were treated, but they still have to make sure they receive regular treatments or they will die.
I was wondering why he mentioned C++, actually.
That's a good point. A C++ app would use Carbon instead of Cocoa.
Yeah "quite a bugs" like erasing your whole User folder when you try to use the Java.net.* classes.
Err... quite a few bugs. Can't say I've seen it erase any folders, though. Should I ask why you have a link to some game site, or should I just tell moderators to mark you as -1 Troll?
...he mentioned Java because there's a Bridge mechanism in OS X that allows Java code to call ObjC code, and ObjC code to call Java code. I've used it myself and found it to be an effective way to write Java programs that are native to the OS X platform. Be warned, however. Differences in the way ObjC and Java handle objects causes quite a bugs. Not everything can be 100% mapped, so you'll find yourself writing some ObjC anyway.
If it helps any, I agree perfectly well. People seem to feel the need to think that humans are not ingenuitive enough to develop stuff on our own. They say stuff like "the Egyptians lifted 300 ton block! We can't even do that today!" At which point I have to point out the Space Shuttle crane, or lifting a 1000 foot ship into drydock. Then I start mentioning technologies like RamJets, Nuclear Thermal Propulsion, and others that had always been considered nothing more than Sci-Fi.
We actually have a lot more tech at our fingertips than we're using today. We're not using it because there's no push to develop it. Not to mention to push to "make everything safer" and round all the corners. Bah.
Hello?! McFly?! That's why it was FUNNY! Now why don't you make like a tree, and get outta here? ;-)
On the other hand, I'm far more concerned about consumer-portable SRG slowly contaminating the water supply after being tossed into a dump much like NiCds are doing today.
This is less of a concern for two reasons. One, the materials would tend to settle in the sediment and become harmless. Both the sediment and the water would provide excellent radiation protection. Remember that Alpha particles (the primary radioparticle released by Pu-238) is easily blocked by a sheet of paper. Your dead skin layer does an even better job.
Oh, and there's *cough* already radioisotopes in your food and water thanks to *cough* nuclear testing in the 50's and 60's.
The one other reason was that my plan called for leasing the devices instead of selling them outright. By leasing them, they could be recovered, refurbished, and even be used to create new (and cheaper) batteries.
I was going to complain than an SRG is way too heavy, but some digging found that a 55 W SRG prototype was only about 27 kg. Not really man-portable for infantry purposes, but infantry electronics are designed for lower power usage, so a smaller one could be created.
No need for a smaller one. Most of the weight in RTGs and SRGs are from the graphite shielding that's used to protect the device during an uncontrolled reentry into the atmosphere. Since an infantry device would be intended for ground use, it would only need to weigh a kilos or two.
Now for vehicles, you might have something there -- just not for civillian cars, in my opinion.
Not enough energy. You need several kilowatts of power to cruise a vehicle at 60 MPH. Accelerating results in a temporary usage of 10's of kilowatts of power. In case you're interested, it takes ~745 Watts to produce one horsepower of drive.
Do you know when the SR 71 started flying?
It began flying in December, 1964. However, it had already been announced by President Johnson in February of 1964! It was in this speech that the President "accidentally" switched the name from RS-71 to SR-71. A little more digging shows that the USAF Chief of Staff had intentionally switched the letters in the President's speech because he liked SR-71 better than RS-71.
B When did they start flying the "Stealth Bomber"?
Similarly, the B-2 bomber was on public display on November 22, 1988, but its first flight wasn't until July 17, 1989. The final product wasn't delivered until 1993, and it didn't see combat until 1999.
Allow me to reiterate my previous point. The government is lousy at keeping secrets! And with this constant Myth of an Aurora out there somewhere, the government would have an extremely difficult time keeping such a craft under wraps. They'd be far more likely to just announce its existence and get it over with. It's not like they'd tell the public anything useful anyway. They'd simply confirm or deny the craft's propulsion method, stealth features, and approximate cruising speed. It's real ceiling of operation would remain classified until it went out of service.
For the very first stoke this will work fine, but after the pressure escapes through the exhaust port. The remaining air in the cylinder is still heated so you will no longer get any thermal expansion from that same air.
:-)
Hmm... I thought that air-cooled Stirling engines worked because the heat would attempt to equalized the temperature inside the cylinder and outside in the open air. Perhaps I was incorrect. Many Stirling designs actually call for some sort of active cooling. NASA uses cycled helium for this purpose.
This is assuming you're not using some spring or relying on the momentum of the shaft somehow.
I was planning that the momentum would be sufficient to keep the device running. However, I have also been concerned about this problem. My alternate design actually has two "half-size" pistons connected to the dynamo. When one goes up, it forces the other one down. It may even make sense to offset the drive shaft such that one piston will finish moving the other piston up (thus exposing more of an air exchange outlet) before driving it back down.
Just my non-expert two cents.
It's more feedback then I ever got from the "experts" on the energy newsgroups.
No, thank you. Sometimes I feel like I'm just beating my head against a wall instead of actually educating anyone. Your response gives me heart that people *are* listening. :-)
In 1985 you might be able to get plutonium from your local corner store, but here in 2004 it's a little harder to come by!
Ok, now THAT was a great joke. Mod parent up as funny!
BTW, I should probably use this opportunity to point out that different forms of Plutonium exist. Pu-239 is useful for bombs and reactors because it easily fissions. However, it has far too long of a half-life to be useful for RTGs and SRGs. Pu-238 OTOH, is great for RTGs and SRGs, but is absolutely useless as a fissionable material.