Photons have zero rest mass, but light has an energy of $h\nu$, where $\nu$ is the frequency, so this gets added on to the mass of our thing.
Oversimplified explanation: Photons are massless so they can go as fast as they want without needing kinetic energy, but even massless things can store energy (think of the massless springs you studied in high school physics). Energy is the same thing as mass, but we still refer to photons as massless, in the same way that we think of an (imaginary) massless spring as such; we don't like to think of potential energy as _being the object_, just somehow _there_.
This makes more sense if you study physics, in no small part due to the fact that we make it all rigorous (though not to the satisfaction of the mathematicians, I guess...).
> Does this mean that if you move an object away from Earth's gravitational influence it will increase in mass because it has more potential energy?
Gravitational potential energy is a little different. It's the energy that the object would have if it fell to earth, it doesn't actually exist until it starts falling. (correct this, i'm sure i'm wrong)
> What about if you heated something up, does it gain mass then?
Yes, but it's incredibly miniscule to the point that it's not worth looking at in most situations
> How about sound? Does the sound of my voice cause imperceptible ripples of increased mass as it vibrates everything that it touches?
This one I think does but it's going to be so small that you also won't notice it. What you would be able to notice though are the subtle changes in density at the peaks and troughs of the wave.
> Is a charged battery heavier than an empty one?
Maybe. This depends on the chemistry of the battery more than anything. Some of them will oxidize as it gives out energy and give off the oxygen when charging. While the energy will contribute slightly to the mass because of the chemcical bonds, the battery will change mass more because of the lost/gained atoms than any other cause.
> Is glass heavier with light travelling through it?
I really don't know how to answer this one. The photon never really becomes part of the glass as far as I'm aware, but some will be absorbed and raise the temperature so maybe?
Think about the opposite - nuclear fission. The energy released when nuke goes off comes from the difference of mass between original atoms and products of the split. This difference is the energy stored in strong nuclear force, binding protons and neutrons together.
I belive I kind of understand what you are saying.
I am confused as to whether or not the photons actually stop moving. Since they halt them by shutting off the transparency it seems that the photons would get trapped and end up bouncing around being absorbed slowly.
Is that why the effect is temporary? The light eventually gets absorbed and disperced though the crystal?
By implanting a small magnet normally in a finger, moving your finger through an electric field causes small movement of the magnet, so you can 'feel' electric fields.
e.g.
http://gizmodo.com/5895555/i-have-a-magnet-implant-in-my-fin...
But there's been a number of people who've done it.
Checked because I remember hearing about the somewhat horrific forced swim test. Idea is mice are trapped in a container fall of water; depression is when they give up and let themselves drown.
Mice float. All the forced swimming test does is measure the time it takes for them to stop paddling.
As far as "torturing" goes, in the US academic studies require submission of protocols to an Institutional Animal Care and Use Committee with proof that any harm caused to an animal is necessary for the study and meets federal guidelines for animal care (and because funding tends to come from federal sources, there is good incentive to meet these requirements). For studies involving pain, nerve regrowth after an insult, or other similar lines of research, injury may be unavoidable in asking the research question, but how the injury is applied must be approved by these committees. Protocols that involve harming an animal tend to be the most stringently regulated by these bodies, even more so than protocols requiring euthanasia. Furthermore, it is usually in the interest of the scientists performing the research to treat their animals consistently well, lest they find themselves with some inexplicable variables to account for.
Now, whether all or any of that merely constitutes "permitted" torture for our own benefit is a different question, but we do try to ensure that animals are treated as well as possible in a given research context.
Someone I knew once explained how their lab had a machine to give mice precisely calibrated amounts of brain damage through impact. The control group had their skull fractured without causing any direct injury to the brain.
This has always struck me as the ickiest thing I've heard, but I'm sure there's much worse out there.
I suspect "making available" would be treated similar to selling.
But if the law is as described in the ref'd comment, I wonder why there aren't sites or books that walk you up to the point where you can provide the invention for your personal use.
My not particularly well informed understanding is that it is more a of a practical exception than a technical one. So a patent holder could try to use the legal system to stop personal use, it just isn't worth doing.
More like we were used to hammers as fine art and flyswatters, when someone went "hey! what a great idea!" and patented smacking metal spikes with them. Such is a large part of the patent field: doing obvious things with common objects, before anyone else says "hey, that idea is obvious and the parts common!" and making others pay to do it.
Wouldn't it be pretty toxic (especially if it's a vapour?) In a sealed component in a datacentre that problem doesn't matter, but they're speculating about home use also.
Probably not, C-F bonds are extremely stable, so perfluoro compounds are biologically inert. The datasheet says they made some animal inhale 10% (!) Novec gas for 4 hours without effect.
It has half-life of 5 days in the atmosphere, so it's not that stable. According to the MSDS it and degrades both when exposed to UV and at high temperature (like those present in a structural fire) into hydrogen fluoride gas, which becomes hydrofluoric acid upon contact with moisture (including biological tissue).
Also you're supposed to dike the area if a major spill occurs, but I'm pretty sure that's just MSDS boilerplate.
The 3M leaflet suggests that you should avoid breathing it, or getting it on your skin or in your eyes, but that you shouldn't be harmed if you ingest it.
I don't know if that's relative to some of the other nastier stuff they sell.
The 3M page seems to show servers dunked in "semi sealed" cabinets of this stuff, which boils, evaporates, cools, and falls back into the tank.
That's essentially average-utilitarian (has the happiness of a random person in the population gone up?); I guess many people are closer to total-utilitarian (ie. the total number of happy/surviving people is also important).
Wouldn't total-utilitiarian then prefer a population of 1000000 mostly unhappy people over a population of 100 very happy people? In that case it would at least be an awkward benchmark, as you just need to procreate as much as possible to get the "best" scenario.
Yes, there's an interesting thing on that here:
http://plato.stanford.edu/entries/repugnant-conclusion/
I haven't looked at enough philosophy to be able to figure out what I'd place myself as, average-utilarianism also seems to lead to morally-counter-intuitive stuff.
Relabelling is the marketing game; to get your businessy-idea-book in the best-sellers list you need everyone to replace "practice makes perfect" with "10000 hours".
Yep. And in fact marketers didn't invent relabelling (Tallyrand had a witty remark that one of the functions of the State is to rename odious institutions and I would not be surprised if Confucius had this phenomenon in mind when he got grumpy about the Rectification of the Names).
Too many rhinos dispersed across too far a distance. Unlike elephants rhinos don't necessarily herd in large groups. Many of the rhinos killed were either alone or in a small group of 2-4.
I'm not sure flooding the market with fake rhino horn is feasible as the underworld will develop its own authentication methods, but one suggestion that has been discussed is to flood the market with rhino horns from the huge stockpiles collected from rhinos who've died from natural causes in the hope that it'll lower the price and reduce the incentive to poach.
> Too many rhinos dispersed across too far a distance. Unlike elephants rhinos don't necessarily herd in large groups. Many of the rhinos killed were either alone or in a small group of 2-4.
My google searching suggests there are 5k-10k black rhinos in the world. Seems plausible to monitor each one with a dedicated UAV, once you take into account economies of scale.
While it's an interesting idea, it's not just possible with today's tech.
Black rhinos are only one subspecies, white rhinos are just as threatened by poaching and there are around 20 000 of those, so you're looking at around 25 000 rhinos in Africa.
You'd need at least three UAVs per rhino, one on station at any given time, one ready to replace it once its endurance runs out and one spare in case something happens to one of the other two. Then there's the problem of actually tracking the rhino 24x7, through night and bad weather, while ensuring that the base station and recovery team stays close.
You'd also need skilled pilots / operators to keep the UAV on station and interpret what's on the screen and, once again, you'd need more than one per rhino to enable 24x7 shifts.
Once you factor in the number of UAVs, the dispersed recovery and handling teams and the need for skilled operators, you could potentially be speaking of 75 000 UAVs and a similar number of teams and pilots / operators. Even if we assume that UAVs with sufficient endurance for this task could be reduced to $500 000 each, that still results in a capital cost of nearly $40 billion, over and above the sure-to-be-mammoth operating costs. So it's not feasible.
A better approach is to fit each rhino with a GPS tracker, which is being done, and to use ranger patrols augmented by technology like UAVs and ground radar to attempt to spot poachers moving in the parks. That's why this is where SANParks and others are focusing their attention and resources.
My claim is that the cost would be much less than $500k/UAV in bulk. And you'd fit the rhinos with GPS trackers so no need for any human operators whatsoever.
I really like the idea of throwing some research dollars at developing imitation rhino horn. The kinds of people who are willing to traffic in endangered species wouldn't blush at passing along counterfeit product, as long as it was hard for the buyer to detect. Is anybody working on this? If not, it might make for a good kickstarter project :P
