Possibly. I don't actually know anything about quantum virtual particles except what I've read related to the theories on how the EM Drive might work. I've got a BS in computer engineering, not a PhD in physics. I can believe that Hawking could have shown that, but I don't know if it has or has not been shown.
Empirical observations trump theory. Theory is an attempt to explain how the universe works, but it does not dictate the universe's workings. Grad-level physics can explain why the EM Drive shouldn't work. Newtonian physics can explain why GPS shouldn't work, too; and yet the accuracy of the results remain as high as ever.
The problem is, according to everybody who has tested it, the EM Drive does produce thrust. When your theory contradicts reality, it is the theory which is discarded (or at least updated). Unless there's some pervasive experimental error in all of the independent observations of this effect - which is possible, but becomes less likely with each successful reproduction - that will need to happen with our understanding of those grad-level physics you studied.
In that case, on your final, you did the equivalent of computing that if a 1kg object (constant mass, initially at rest relative to you) produces 10^8 N of thrust in a straight line away from you for six seconds, it'll be going at just over twice the speed of light relative to you afterwards. Perfectly consistent with physics as it was near-universally understood until 110 years ago...
Of course, in this case, we have an experimental result before we have a fully consistent theory to explain it. In a reversal from the way much (though not all) recent physics progress has been made, the empiricists appear to be outracing the theorists. That's why right now there are a number of hypotheses, each of which have problems. More experiments will allow us to refine those hypotheses and throw out those which are shown to be incorrect (for example, Guido Fetta - of the Cannae Drive - had a theory that radial slots inside the drive's chamber were required; NASA demonstrated that they weren't). More time will also allow theoretical physicists to work out the underpinnings of how this happens. That will expand our understanding of the universe, give us the tools to predict future experimental results (rather than trying to explain the result after the fact), and open new branches of scientific exploration.
The above paragraph is, of course, predicated on the assumption that the effect does happen. I'm not discarding the possibility of experimental error at this point. It is simply becoming less and less plausible of an explanation.
First of all, a horse cannot continuously accelerate given a constant amount of electricity (or even hay). Horses need to push against something (the ground) and can only do that so fast; there is a cap on their maximum velocity. In practice, for any given real-world flywheel and generator, there would be a max speed for an EM Drive-driven rotor too - due to centrifugal force, if nothing else - but there's no theoretical maximum that I'm aware of.
Read david_thornley's comment above for the math. The basic idea is that if you have something which increases its velocity at a constant rate and for constant energy, then its kinetic energy growth will eventually exceed the energy driving it. That's because kinetic energy grows as the square of velocity.
Of course, a conventional rocket could accelerate continuously (unlike a horse) if you could keep it supplied with fuel. That's the big "if", though; the total energy you could get out of it is never more than the rest energy of the fuel you put in. Imagine a total-conversion antimatter rocket, which is probably the most efficient kind of reaction drive possible (since you are literally extracting all the energy possible from a given mass). It produces an incredible amount of energy for the fuel you put in... but at the end of the day, it runs out of fuel (stops accelerating) and you have to put more in, consuming the mass/energy of something from outside the system. It can't run forever without consuming an infinite amount of mass.
The EM Drive has no fuel requirement at all. Electricity isn't a thing that can be consumed, it's a process, the motion of electrons. A generator can keep applying (electromotive) force to those electrons, keeping them moving forever as long as there's an energy input to the generator itself. The EM Drive can keep producing thrust as long as it has electricity. Once you reach the break-even point, no outside mass/energy is required.
Except it doesn't. The microwaves are not emitted anywhere. They are generated into a sealed chamber. There's nowhere they can go.
The formulae you listed would be useful to describe thrust from a photon drive (or light drive), but those need an open-ended emitter. Also, the results you get from them are about three orders of magnitude too low for the observed ratio of thrust to power. A 700W microwave photon drive wouldn't be detectable by the experimental apparatus.
A) That's one hypothesis among several, and many physicists claim it is, to use your term, "bollocks". I did mention there are multiple theories about how it works. They all have supporters, but they all have counterarguments too.
B) No, classical rocket engines push real particles one way and itself the other way. Unless you intend to claim that "virtual" and "real" particles are the same thing, it's not working "exactly the same way". Analogously, perhaps, but hardly "exactly the same".
Oh, and just for the heck of it: C) To conclusively state that the EM Drive works according to your preferred theory is quite absurd unless you're an extremely well-educated theoretical physicist, and only slightly less even then. To even *claim* that I claimed anything about how the drive works, much less that my supposed idea is "bollocks", indicates a lack of reading comprehension, lack of understanding of the concept of scientific hypotheses, and lack of maturity.
Not indefinitely, just over a long time. Ion engines consume fuel (which they ionize, and then throw the ions out the back of the drive, hence the name) so an ion engine still needs to haul its reaction mass along for the ride, and stops being able to thrust once it runs out of stuff to ionize and expel.
The fuel (energy storage) used to produce the electricity doesn't need to be internal to the craft, though. Photovoltaic panels, for example, take electromagnetic energy (photons), such as stars (big balls of fuel) produce, and turn it into electricity. A magnetron (such as the one inside an EM Drive) can turn that electricity back into electromagnetic energy. You now have a relatively tiny craft that can thrust forever so long as there's a star close enough to provide photons (in reasonable quantity). Maybe not viable for a starship, but it could completely revolutionize intra-system travel.
I wrote a comment on this up above, but just to help you understand...
1) No, the ion drive does not use electricity to produce thrust. Ion drives, as their name suggests, use ions to produce thrust. The ions are accelerated using fields generated via electric power, but that's no more a case of using electricity to (directly) produce thrust than an electric car is (the car pushes against the road, imparting momentum to the earth which balances the momentum imparted to the car). 2) Yes, it sounds like a free energy machine. If a given amount of electrical power produces a given thrust, constantly, without consuming any fuel, then you can generate unlimited energy by attaching this thing to a flywheel or rotor arm that drives a generator and it will produce more energy than it requires to drive the thruster. Some of the current theories about this thing claim that it won't do that, that its efficiency will go down the faster it's moving (relative to a given frame of reference). 3) No, electricity is not fuel. Electricity is not a thing. It is a process. Electricity is the motion of electrons. It is a form of energy. Fuel is a way to store energy, but it is not energy itself. You can generate electricity from many things, including fuel, and there are many forms of chemical devices with electrical potential energy - we usually call them batteries - but electricity is not, itself, fuel. Now, the energy still needs to come from somewhere (unless this drive does turn out to be usable to get more energy out than is put in, which would turn *all* of physics on its head) and that "somewhere" is usually fuel of some kind... but it can be things like uranium in a nuclear reactor that is usable for decades from a tiny amount of mass, or hydrogen in the sun producing photons as it fuses and those photons being captured and used to move electrons via the photoelectric effect (in layman's terms, solar panels).
Scientists Confirm 'Impossible' EM Drive Propulsion
Science News, Space / July 27, 2015 / by Giulio Prisco/
Later today, July 27, German scientists will present new experimental results on the controversial, "impossible" EM Drive, at the American Institute for Aeronautics and Astronautics' Propulsion and Energy Forum in Orlando. The presentation is titled "Direct Thrust Measurements of an EmDrive and Evaluation of Possible Side-Effects."
Presenter Martin Tajmar is a professor and chair for Space Systems at the Dresden University of Technology, interested in space propulsion systems and breakthrough propulsion physics.
A Revolutionary Development for Space Travel
The EM Drive (Electro Magnetic Drive) uses electromagnetic microwave cavities to directly convert electrical energy to thrust without the need to expel any propellant. First proposed by Satellite Propulsion Research, a research company based in the UK founded by aerospace engineer Roger Shawyer, the EM Drive concept was predictably scorned by much of the mainstream research community for allegedly violating the laws of physics, including the conservation of momentum.
However, NASA Eagleworks – an advanced propulsion research group led by Dr. Harold G. “Sonny” White at the Johnson Space Center (JSC) – investigated the EM Drive and presented encouraging test results in 2014 at the 50th Joint Propulsion Conference.
White proposes that the EM Drive’s thrust is due to virtual particles in the quantum vacuum that behave like propellant ions in magneto-hydrodynamical propulsion systems, extracting "fuel" from the very fabric of space-time and eliminating the need to carry propellant. While a number of scientists criticize White's theoretical model, others feel that he is at least pointing to the right direction. The NASASpaceFlight website and forums have emerged as unofficial news source and discussion space for all things related to the EM Drive and related breakthrough space propulsion proposals such as the Cannae Drive.
Shawyer has often been dismissed by the research establishment for not having peer-reviewed scientific publications, but White and Tajmar have impeccable credentials that put them beyond cheap dismissal and scorn. Physics is an experimental science, and the fact that the EM Drive works is confirmed in the lab. "This is the first time that someone with a well-equipped lab and a strong background in tracking experimental error has been involved, rather than engineers who may be unconsciously influenced by a desire to see it work," notes Wired referring to Tajmar's work.
Hacked has obtained a copy of Tajmar's Propulsion and Energy Forum paper, co-authored by G. Fiedler.
"Our measurements reveal thrusts as expected from previous claims after carefully studying thermal and electromagnetic interferences," note the researchers. "If true, this could certainly revolutionize space travel."
“The nature of the thrusts observed is still unclear.”
"Additional tests need to be carried out to study the magnetic interaction of the power feeding lines used for the liquid metal contacts," conclude the researchers. "Nevertheless, we do observe thrusts close to the magnitude of the actual predictions after eliminating many possible error sources that should warrant further investigation into the phenomena. Next steps include better magnetic shielding, further vacuum tests and improved EMDrive models with higher Q factors and electronics that allow tuning for optimal operation."
Contrary to sensationalist reports published by the sensationalist press, the EM Drive is not a "warp drive" for faster than
Finally, in the hacked.com article, rather than expelling "propellant", aren't you expelling "reaction mass"?
Where did you get that idea? The article never uses the term "reaction mass" (or even either word individually). The only references to "propellant" are to explain what the EM drive *doesn't* use, or to contrast the EM Drive with ion drives (which do have a propellant, the ions that the drive expels).
Also, for the record, "reaction mass" is just "propellant" that has been given momentum and kicked out of the vehicle. They are the same thing at different points in time, and the terms are often used interchangeably.
It appears to impart momentum to something without an opposite momentum imparted to anything else... you know, the basic concept of how every other propulsion system in the world works?
When you walk, your feet push against the ground, imparting a (tiny, relative to the mass of the Earth) amount of momentum to it at the same time that your feet impart momentum to your body. When you sail a boat, the sails alter the momentum of the wind, and an opposite alteration is imparted to the momentum of the boat. When a rocket engine fires, it releases exhaust with a lot of momentum going one way, and the rocket receives the momentum going the other way. This model holds for any kind of propelling of anything. Even a flashlight projecting photons imparts a tiny, tiny bit of momentum to your hand, to your body, to the earth. Magnetic propulsion, chemical propulsion, ion propulsion... all of them operate on the principle of "we go this way, by making something else go that way".
The EM Drive appears to go one way without making anything else go the other way. It releases no exhaust, pushes against no solid or fluid, emits no photons, and interacts with no external magnetic fields. We don't know how it works (there are a number of theories, none of which are that widely accepted), and we still aren't 100% sure it does work (maybe it's still all experimental error... that becomes less likely with each independent verification, but extraordinary claims call for extraordinary evidence), but if it does work it does so in a way that is outside our current understanding of physics. That is a Really Big Deal.
Yep, the microwave cavity is sealed. Nowhere for them to go.
Also, even in these early and probably very inefficient (assuming the thing really works) trials, the thrust/power ratio is something like three orders of magnitude beyond what you'd get from a photon drive. No "microwave-emitting thruster" operating at these power levels would come even close to the sensitivity threshold of the experimental apparatus, much less reach several times that threshold.
That's actually not *entirely* true... humans haven't been making artificially modulated RF for a millennium yet, but artificial sources of EM (remember, *light* is EM) have existed practically as long as any form of civilization has. Cities are visible from space. Much less so when they're lit by candles and fireplaces than when they're lit by all the myriad electric sources found in modern cities, and there's a nearly-incomprehensible difference between LEO "from space" and interstellar "from space", of course. It also wouldn't tell the aliens anything about us (even if they had the sensors to detect those tiny motes of firelight, and distinguish them from natural sources) other than that we'd invented fire. Still, that's a lot, in some ways.
Are you counting Firefox with or without Firebug? Feature-wise, Firebug is still pretty much the gold standard... but it's dog-slow even without turning on the optional stuff that makes it even slower, and it's a third-party aftermarket install. Firefox's built-in dev tools have gotten better in the last few builds, but (as you noted) are still well behind IE11 (or Chrome). I haven't tried Edge yet.
Good question. IE has had ad-blocking and tracking protection (same feature, Tracking Protection Lists just can also be used to block ads) for a few versions now, and I think there's actually a legit AdBlock Plus extension for IE (haven't tried it). On the other hand, Edge is supposed to be super-minimalist, and I'm not sure if it'll support any kind of browser add-in (at least, initially). Tracking Protection and TPLs like IE9-11 have had is harder to say (I haven't tried it yet).
Worst case you can always use a HOSTS file, but of course you can also just use a non-Microsoft browser.
Pilot wouldn't have needed to. Dragon 2 has automatic abort capabilities (even when unmanned). It would have separated from the second stage - probably firing its SuperDraco thrusters - and then automatically deployed parachutes once it was a safe distance away.
Dragon 1 doesn't have the SuperDracos (only the much smaller Draco attitude control thrusters) so it wouldn't have been able to put as much distance between itself and the booster, but from the video and the telemetry it looks like the capsule survived the (accidental) separation anyhow. It could have deployed its parachutes and probably survived the landing, but it wasn't programmed to do so. They have added it to the Dragon 1 programming now though.
Failures that occur high enough to land under parachutes, slow enough to get away from the inevitable explosion without heavy rockets, and early enough in flight that there's no time to manually enable the landing sequence are... really, really rare in rocketry. Usually you either fail at liftoff (see Orbital's last attempt to launch Antares), fail rapidly and catastrophically during liftoff (any number of examples), or fail once in orbit (often, though not always, at stage separation). In orbit you have time to make a decision and send orders. On the launchpad you can't land safely (without abort rockets). In midair you *usually* can't get away in time (without abort rockets). This was an exception to the "in midair" usual failure case; there were nine seconds from beginning of the failure to loss of vehicle, and in fact the capsule had already tumbled free (and probably *could* have used its ACS thrusters to put some extra distance between itself and the booster.
One thought, though: what about, in the case of a pre-separation second-stage failure, executing MECO 1 (Main Engine Cut Off, when the Falcon 9 first stage kills its rockets) early and doing an emergency stage separation? Normally there's no point - the first stage on most launch vehicles has no purpose if the launch fails and nowhere to go even if it separates safely - but the Falcon 9 first stage is designed for reusability. Emergency MECO, separate the stages, use the ACS and/or grid fins to steer clear of the second stage, and then fire up the main engines again and aim for the droneship or other landing pad. You'd need to be quick about it, and it might still not work, but if it does you've saved a booster worth $70,000,000 USD. Well, that and demonstrated the first successful first stage recovery ever, but assuming that becomes as routine as Musk wants it to be...
Actually, it would have been super cool if the first successful recovery of the first stage had been an emergency abort!
Not necessarily. Sometimes companies intentionally order small numbers for their initial run of a product. If it doesn't sell well, they waste less money. If it sells well, they can spin the "can't keep them on the shelf; backordered for months!" story. That kind of thing actually *increases* appeal; the handful of people who buy something other than that company's product when they can't get it immediately are overwhelmed by the number of people who wouldn't have bought such a product at all until they heard how in-demand it was (must mean it's great, right?).
Gaaaaah why do people keep recommending this *STUPID* approach? DO NOT block update servers! If you're going to do that, do yourself *and* the rest of us a favor and just disconnect your computer altogether...
Here: https://technet.microsoft.com/... Microsoft's own documentation, years old and still valid, explaining how to control all aspects of Windows Update with simple registry changes. Yes, it's annoying that they removed the brain-dead-easy UI for doing so, but the problem with brain-dead-easy UIs that allow making bad decisions is that brain-dead people will use them.
I view this kind of thing as a shibboleth for "are you sufficiently competent to administrate your own computer?". It's amazing and horrifying how many people in this thread have failed that. Did *any* of you try typing "windows update registry" into a browser search box, for example?
That's an abysmally stupid way to do this (then you never get updates) compared to the many superior alternatives, many of which were posted in this discussion...
but yes, you could do that. You could also just disconnect your machine from the Internet altogether, which in terms of overall utility is probably better than leaving it connected but unpatched.
Or, you could, you know, not be a *complete* idiot and use the clearly-explained steps for controlling this behavior ( https://technet.microsoft.com/... ) even if you want to be a *minor* idiot and run "Windows n00b edition". Or you could run an edition of Windows targeted at people who actually have a hope in hell of correctly administrating their own Internet-connected machine.
Yep. In fact, you're even more correct than you realize... 1) Microsoft has done this before! Windows RT has the same "no option to not update" behavior. As you say, they just removed the UI for changing the automatic update options, but the update service still runs exactly the same way including respecting the same registry keys. 2) No need to go find anything! Microsoft has already documented it all for you, listing what registry keys and values do what, and what the valid values are. https://technet.microsoft.com/... (scroll down to the Automatic Updates section).
Manual control over a ton of security stuff, like advanced firewall configuration and user account privileges. Encrypting File System and BitLocker. The ability to join domains. Support for Remote Desktop server (though still limited to one interactive session active at a time unless you go all the way to Server).
I'm sure there's other stuff, that's just the things I notice most are missing from Home.
Windows does actually support snapshots. Volume Shadow Copies are snapshots - either diffs or full images - and you can create or restore them at pretty much any time. Updates, driver installs, and major product installs all trigger creation automatically. "System Restore" uses these snapshots. The restore duration is definitely perceptible, but - while I don't know its time complexity - it doesn't take very long (less than a minute?)
There's an arguably even easier option: take control of Windows (Automatic) Update behavior by tweaking a single registry key. Here, Microsoft will even tell you which one and what the settings mean: https://technet.microsoft.com/... (scroll down for the automatic update options). You can also, as Hairyfeet mentioned above, disable the WU service except when you want to manually run it, but that's definitely not ideal because you *should* promptly install most updates. The registry change lets you select "Notify me of updates / download them, but let me choose when to install", and it works even on OS editions that have removed that option from the UI. It's like a really easy "I'm not completely incompetent at Windows administration" test...
With that said, the AC has a point about the advantages of using Pro editions of Windows. One of the big differentiators is transparent encryption; Home editions don't have any built-in support for encrypting data at rest, so if your laptop gets stolen attackers can take anything on the hard drive. My girlfriend has been dealing with the aftermath of this for a few weeks now (as if having her computer stolen wasn't bad enough), with constant attempts at various kinds of identity theft. It sucks. Encrypt your shit! While Pro editions of Windows have had Encrypting File System for ages, it is per-file (or per-directory) and depends on you having a really strong password, since attackers can still pull the SAM and mount an offline attack. Since Win8 (for Pro; Vista and Win7 had it in Enterprise and Ultimate too) there's also BitLocker full volume encryption. I really wish Microsoft would make this available on all installs - they did for RT and phone, but not for PCs - but it's worth the upgrade to Pro. I also wish they would make it easier to use BitLocker without a TPM - it's entirely possible, you just need to change a setting most people don't even know exists, much less know how to find - but again, this is totally worth doing if you don't have a TPM.
Plus all the behind-the-scenes improvements made in Win8.x (high-entropy ASLR, RAM page combining, etc.), support for modern hardware (not just DX12, but also things like native USB3 support), and user-facing improvements (vastly improved multi-monitor support, settings and such synchronization across machines, etc.). Hell, some people even like some of the Store apps (and with Win10 bringing the ability to run them windowed on the desktop - as should have been possible from the start - a large part of the reasons to *not* use them goes away).
Slashdot Mirror
Possibly. I don't actually know anything about quantum virtual particles except what I've read related to the theories on how the EM Drive might work. I've got a BS in computer engineering, not a PhD in physics. I can believe that Hawking could have shown that, but I don't know if it has or has not been shown.
Empirical observations trump theory. Theory is an attempt to explain how the universe works, but it does not dictate the universe's workings. Grad-level physics can explain why the EM Drive shouldn't work. Newtonian physics can explain why GPS shouldn't work, too; and yet the accuracy of the results remain as high as ever.
The problem is, according to everybody who has tested it, the EM Drive does produce thrust. When your theory contradicts reality, it is the theory which is discarded (or at least updated). Unless there's some pervasive experimental error in all of the independent observations of this effect - which is possible, but becomes less likely with each successful reproduction - that will need to happen with our understanding of those grad-level physics you studied.
In that case, on your final, you did the equivalent of computing that if a 1kg object (constant mass, initially at rest relative to you) produces 10^8 N of thrust in a straight line away from you for six seconds, it'll be going at just over twice the speed of light relative to you afterwards. Perfectly consistent with physics as it was near-universally understood until 110 years ago...
Of course, in this case, we have an experimental result before we have a fully consistent theory to explain it. In a reversal from the way much (though not all) recent physics progress has been made, the empiricists appear to be outracing the theorists. That's why right now there are a number of hypotheses, each of which have problems. More experiments will allow us to refine those hypotheses and throw out those which are shown to be incorrect (for example, Guido Fetta - of the Cannae Drive - had a theory that radial slots inside the drive's chamber were required; NASA demonstrated that they weren't). More time will also allow theoretical physicists to work out the underpinnings of how this happens. That will expand our understanding of the universe, give us the tools to predict future experimental results (rather than trying to explain the result after the fact), and open new branches of scientific exploration.
The above paragraph is, of course, predicated on the assumption that the effect does happen. I'm not discarding the possibility of experimental error at this point. It is simply becoming less and less plausible of an explanation.
First of all, a horse cannot continuously accelerate given a constant amount of electricity (or even hay). Horses need to push against something (the ground) and can only do that so fast; there is a cap on their maximum velocity. In practice, for any given real-world flywheel and generator, there would be a max speed for an EM Drive-driven rotor too - due to centrifugal force, if nothing else - but there's no theoretical maximum that I'm aware of.
Read david_thornley's comment above for the math. The basic idea is that if you have something which increases its velocity at a constant rate and for constant energy, then its kinetic energy growth will eventually exceed the energy driving it. That's because kinetic energy grows as the square of velocity.
Of course, a conventional rocket could accelerate continuously (unlike a horse) if you could keep it supplied with fuel. That's the big "if", though; the total energy you could get out of it is never more than the rest energy of the fuel you put in. Imagine a total-conversion antimatter rocket, which is probably the most efficient kind of reaction drive possible (since you are literally extracting all the energy possible from a given mass). It produces an incredible amount of energy for the fuel you put in... but at the end of the day, it runs out of fuel (stops accelerating) and you have to put more in, consuming the mass/energy of something from outside the system. It can't run forever without consuming an infinite amount of mass.
The EM Drive has no fuel requirement at all. Electricity isn't a thing that can be consumed, it's a process, the motion of electrons. A generator can keep applying (electromotive) force to those electrons, keeping them moving forever as long as there's an energy input to the generator itself. The EM Drive can keep producing thrust as long as it has electricity. Once you reach the break-even point, no outside mass/energy is required.
Except it doesn't. The microwaves are not emitted anywhere. They are generated into a sealed chamber. There's nowhere they can go.
The formulae you listed would be useful to describe thrust from a photon drive (or light drive), but those need an open-ended emitter. Also, the results you get from them are about three orders of magnitude too low for the observed ratio of thrust to power. A 700W microwave photon drive wouldn't be detectable by the experimental apparatus.
A) That's one hypothesis among several, and many physicists claim it is, to use your term, "bollocks". I did mention there are multiple theories about how it works. They all have supporters, but they all have counterarguments too.
B) No, classical rocket engines push real particles one way and itself the other way. Unless you intend to claim that "virtual" and "real" particles are the same thing, it's not working "exactly the same way". Analogously, perhaps, but hardly "exactly the same".
Oh, and just for the heck of it:
C) To conclusively state that the EM Drive works according to your preferred theory is quite absurd unless you're an extremely well-educated theoretical physicist, and only slightly less even then. To even *claim* that I claimed anything about how the drive works, much less that my supposed idea is "bollocks", indicates a lack of reading comprehension, lack of understanding of the concept of scientific hypotheses, and lack of maturity.
Good day to you.
Not indefinitely, just over a long time. Ion engines consume fuel (which they ionize, and then throw the ions out the back of the drive, hence the name) so an ion engine still needs to haul its reaction mass along for the ride, and stops being able to thrust once it runs out of stuff to ionize and expel.
The fuel (energy storage) used to produce the electricity doesn't need to be internal to the craft, though. Photovoltaic panels, for example, take electromagnetic energy (photons), such as stars (big balls of fuel) produce, and turn it into electricity. A magnetron (such as the one inside an EM Drive) can turn that electricity back into electromagnetic energy. You now have a relatively tiny craft that can thrust forever so long as there's a star close enough to provide photons (in reasonable quantity). Maybe not viable for a starship, but it could completely revolutionize intra-system travel.
I wrote a comment on this up above, but just to help you understand...
1) No, the ion drive does not use electricity to produce thrust. Ion drives, as their name suggests, use ions to produce thrust. The ions are accelerated using fields generated via electric power, but that's no more a case of using electricity to (directly) produce thrust than an electric car is (the car pushes against the road, imparting momentum to the earth which balances the momentum imparted to the car).
2) Yes, it sounds like a free energy machine. If a given amount of electrical power produces a given thrust, constantly, without consuming any fuel, then you can generate unlimited energy by attaching this thing to a flywheel or rotor arm that drives a generator and it will produce more energy than it requires to drive the thruster. Some of the current theories about this thing claim that it won't do that, that its efficiency will go down the faster it's moving (relative to a given frame of reference).
3) No, electricity is not fuel. Electricity is not a thing. It is a process. Electricity is the motion of electrons. It is a form of energy. Fuel is a way to store energy, but it is not energy itself. You can generate electricity from many things, including fuel, and there are many forms of chemical devices with electrical potential energy - we usually call them batteries - but electricity is not, itself, fuel. Now, the energy still needs to come from somewhere (unless this drive does turn out to be usable to get more energy out than is put in, which would turn *all* of physics on its head) and that "somewhere" is usually fuel of some kind... but it can be things like uranium in a nuclear reactor that is usable for decades from a tiny amount of mass, or hydrogen in the sun producing photons as it fuses and those photons being captured and used to move electrons via the photoelectric effect (in layman's terms, solar panels).
Scientists Confirm 'Impossible' EM Drive Propulsion
Science News, Space / July 27, 2015 / by Giulio Prisco/
Later today, July 27, German scientists will present new experimental results on the controversial, "impossible" EM Drive, at the American Institute for Aeronautics and Astronautics' Propulsion and Energy Forum in Orlando. The presentation is titled "Direct Thrust Measurements of an EmDrive and Evaluation of Possible Side-Effects."
Presenter Martin Tajmar is a professor and chair for Space Systems at the Dresden University of Technology, interested in space propulsion systems and breakthrough propulsion physics.
A Revolutionary Development for Space Travel
The EM Drive (Electro Magnetic Drive) uses electromagnetic microwave cavities to directly convert electrical energy to thrust without the need to expel any propellant. First proposed by Satellite Propulsion Research, a research company based in the UK founded by aerospace engineer Roger Shawyer, the EM Drive concept was predictably scorned by much of the mainstream research community for allegedly violating the laws of physics, including the conservation of momentum.
However, NASA Eagleworks – an advanced propulsion research group led by Dr. Harold G. “Sonny” White at the Johnson Space Center (JSC) – investigated the EM Drive and presented encouraging test results in 2014 at the 50th Joint Propulsion Conference.
White proposes that the EM Drive’s thrust is due to virtual particles in the quantum vacuum that behave like propellant ions in magneto-hydrodynamical propulsion systems, extracting "fuel" from the very fabric of space-time and eliminating the need to carry propellant. While a number of scientists criticize White's theoretical model, others feel that he is at least pointing to the right direction. The NASASpaceFlight website and forums have emerged as unofficial news source and discussion space for all things related to the EM Drive and related breakthrough space propulsion proposals such as the Cannae Drive.
Shawyer has often been dismissed by the research establishment for not having peer-reviewed scientific publications, but White and Tajmar have impeccable credentials that put them beyond cheap dismissal and scorn. Physics is an experimental science, and the fact that the EM Drive works is confirmed in the lab. "This is the first time that someone with a well-equipped lab and a strong background in tracking experimental error has been involved, rather than engineers who may be unconsciously influenced by a desire to see it work," notes Wired referring to Tajmar's work.
Hacked has obtained a copy of Tajmar's Propulsion and Energy Forum paper, co-authored by G. Fiedler.
"Our measurements reveal thrusts as expected from previous claims after carefully studying thermal and electromagnetic interferences," note the researchers. "If true, this could certainly revolutionize space travel."
"Additional tests need to be carried out to study the magnetic interaction of the power feeding lines used for the liquid metal contacts," conclude the researchers. "Nevertheless, we do observe thrusts close to the magnitude of the actual predictions after eliminating many possible error sources that should warrant further investigation into the phenomena. Next steps include better magnetic shielding, further vacuum tests and improved EMDrive models with higher Q factors and electronics that allow tuning for optimal operation."
Contrary to sensationalist reports published by the sensationalist press, the EM Drive is not a "warp drive" for faster than
Where did you get that idea? The article never uses the term "reaction mass" (or even either word individually). The only references to "propellant" are to explain what the EM drive *doesn't* use, or to contrast the EM Drive with ion drives (which do have a propellant, the ions that the drive expels).
Also, for the record, "reaction mass" is just "propellant" that has been given momentum and kicked out of the vehicle. They are the same thing at different points in time, and the terms are often used interchangeably.
It appears to impart momentum to something without an opposite momentum imparted to anything else... you know, the basic concept of how every other propulsion system in the world works?
When you walk, your feet push against the ground, imparting a (tiny, relative to the mass of the Earth) amount of momentum to it at the same time that your feet impart momentum to your body.
When you sail a boat, the sails alter the momentum of the wind, and an opposite alteration is imparted to the momentum of the boat.
When a rocket engine fires, it releases exhaust with a lot of momentum going one way, and the rocket receives the momentum going the other way.
This model holds for any kind of propelling of anything. Even a flashlight projecting photons imparts a tiny, tiny bit of momentum to your hand, to your body, to the earth. Magnetic propulsion, chemical propulsion, ion propulsion... all of them operate on the principle of "we go this way, by making something else go that way".
The EM Drive appears to go one way without making anything else go the other way. It releases no exhaust, pushes against no solid or fluid, emits no photons, and interacts with no external magnetic fields. We don't know how it works (there are a number of theories, none of which are that widely accepted), and we still aren't 100% sure it does work (maybe it's still all experimental error... that becomes less likely with each independent verification, but extraordinary claims call for extraordinary evidence), but if it does work it does so in a way that is outside our current understanding of physics. That is a Really Big Deal.
One way or another, this is exciting!
Yep, the microwave cavity is sealed. Nowhere for them to go.
Also, even in these early and probably very inefficient (assuming the thing really works) trials, the thrust/power ratio is something like three orders of magnitude beyond what you'd get from a photon drive. No "microwave-emitting thruster" operating at these power levels would come even close to the sensitivity threshold of the experimental apparatus, much less reach several times that threshold.
That's actually not *entirely* true... humans haven't been making artificially modulated RF for a millennium yet, but artificial sources of EM (remember, *light* is EM) have existed practically as long as any form of civilization has. Cities are visible from space. Much less so when they're lit by candles and fireplaces than when they're lit by all the myriad electric sources found in modern cities, and there's a nearly-incomprehensible difference between LEO "from space" and interstellar "from space", of course. It also wouldn't tell the aliens anything about us (even if they had the sensors to detect those tiny motes of firelight, and distinguish them from natural sources) other than that we'd invented fire. Still, that's a lot, in some ways.
Are you counting Firefox with or without Firebug? Feature-wise, Firebug is still pretty much the gold standard... but it's dog-slow even without turning on the optional stuff that makes it even slower, and it's a third-party aftermarket install. Firefox's built-in dev tools have gotten better in the last few builds, but (as you noted) are still well behind IE11 (or Chrome). I haven't tried Edge yet.
Good question. IE has had ad-blocking and tracking protection (same feature, Tracking Protection Lists just can also be used to block ads) for a few versions now, and I think there's actually a legit AdBlock Plus extension for IE (haven't tried it). On the other hand, Edge is supposed to be super-minimalist, and I'm not sure if it'll support any kind of browser add-in (at least, initially). Tracking Protection and TPLs like IE9-11 have had is harder to say (I haven't tried it yet).
Worst case you can always use a HOSTS file, but of course you can also just use a non-Microsoft browser.
Pilot wouldn't have needed to. Dragon 2 has automatic abort capabilities (even when unmanned). It would have separated from the second stage - probably firing its SuperDraco thrusters - and then automatically deployed parachutes once it was a safe distance away.
Dragon 1 doesn't have the SuperDracos (only the much smaller Draco attitude control thrusters) so it wouldn't have been able to put as much distance between itself and the booster, but from the video and the telemetry it looks like the capsule survived the (accidental) separation anyhow. It could have deployed its parachutes and probably survived the landing, but it wasn't programmed to do so. They have added it to the Dragon 1 programming now though.
Failures that occur high enough to land under parachutes, slow enough to get away from the inevitable explosion without heavy rockets, and early enough in flight that there's no time to manually enable the landing sequence are... really, really rare in rocketry. Usually you either fail at liftoff (see Orbital's last attempt to launch Antares), fail rapidly and catastrophically during liftoff (any number of examples), or fail once in orbit (often, though not always, at stage separation). In orbit you have time to make a decision and send orders. On the launchpad you can't land safely (without abort rockets). In midair you *usually* can't get away in time (without abort rockets). This was an exception to the "in midair" usual failure case; there were nine seconds from beginning of the failure to loss of vehicle, and in fact the capsule had already tumbled free (and probably *could* have used its ACS thrusters to put some extra distance between itself and the booster.
One thought, though: what about, in the case of a pre-separation second-stage failure, executing MECO 1 (Main Engine Cut Off, when the Falcon 9 first stage kills its rockets) early and doing an emergency stage separation? Normally there's no point - the first stage on most launch vehicles has no purpose if the launch fails and nowhere to go even if it separates safely - but the Falcon 9 first stage is designed for reusability. Emergency MECO, separate the stages, use the ACS and/or grid fins to steer clear of the second stage, and then fire up the main engines again and aim for the droneship or other landing pad. You'd need to be quick about it, and it might still not work, but if it does you've saved a booster worth $70,000,000 USD. Well, that and demonstrated the first successful first stage recovery ever, but assuming that becomes as routine as Musk wants it to be...
Actually, it would have been super cool if the first successful recovery of the first stage had been an emergency abort!
Not necessarily. Sometimes companies intentionally order small numbers for their initial run of a product. If it doesn't sell well, they waste less money. If it sells well, they can spin the "can't keep them on the shelf; backordered for months!" story. That kind of thing actually *increases* appeal; the handful of people who buy something other than that company's product when they can't get it immediately are overwhelmed by the number of people who wouldn't have bought such a product at all until they heard how in-demand it was (must mean it's great, right?).
Simple marketing trick.
Gaaaaah why do people keep recommending this *STUPID* approach? DO NOT block update servers! If you're going to do that, do yourself *and* the rest of us a favor and just disconnect your computer altogether...
Here: https://technet.microsoft.com/... Microsoft's own documentation, years old and still valid, explaining how to control all aspects of Windows Update with simple registry changes. Yes, it's annoying that they removed the brain-dead-easy UI for doing so, but the problem with brain-dead-easy UIs that allow making bad decisions is that brain-dead people will use them.
I view this kind of thing as a shibboleth for "are you sufficiently competent to administrate your own computer?". It's amazing and horrifying how many people in this thread have failed that. Did *any* of you try typing "windows update registry" into a browser search box, for example?
That's an abysmally stupid way to do this (then you never get updates) compared to the many superior alternatives, many of which were posted in this discussion...
but yes, you could do that. You could also just disconnect your machine from the Internet altogether, which in terms of overall utility is probably better than leaving it connected but unpatched.
Or, you could, you know, not be a *complete* idiot and use the clearly-explained steps for controlling this behavior ( https://technet.microsoft.com/... ) even if you want to be a *minor* idiot and run "Windows n00b edition". Or you could run an edition of Windows targeted at people who actually have a hope in hell of correctly administrating their own Internet-connected machine.
Yep. In fact, you're even more correct than you realize...
1) Microsoft has done this before! Windows RT has the same "no option to not update" behavior. As you say, they just removed the UI for changing the automatic update options, but the update service still runs exactly the same way including respecting the same registry keys.
2) No need to go find anything! Microsoft has already documented it all for you, listing what registry keys and values do what, and what the valid values are. https://technet.microsoft.com/... (scroll down to the Automatic Updates section).
Manual control over a ton of security stuff, like advanced firewall configuration and user account privileges. Encrypting File System and BitLocker. The ability to join domains. Support for Remote Desktop server (though still limited to one interactive session active at a time unless you go all the way to Server).
I'm sure there's other stuff, that's just the things I notice most are missing from Home.
Windows does actually support snapshots. Volume Shadow Copies are snapshots - either diffs or full images - and you can create or restore them at pretty much any time. Updates, driver installs, and major product installs all trigger creation automatically. "System Restore" uses these snapshots. The restore duration is definitely perceptible, but - while I don't know its time complexity - it doesn't take very long (less than a minute?)
There's an arguably even easier option: take control of Windows (Automatic) Update behavior by tweaking a single registry key. Here, Microsoft will even tell you which one and what the settings mean:
https://technet.microsoft.com/... (scroll down for the automatic update options).
You can also, as Hairyfeet mentioned above, disable the WU service except when you want to manually run it, but that's definitely not ideal because you *should* promptly install most updates. The registry change lets you select "Notify me of updates / download them, but let me choose when to install", and it works even on OS editions that have removed that option from the UI. It's like a really easy "I'm not completely incompetent at Windows administration" test...
With that said, the AC has a point about the advantages of using Pro editions of Windows. One of the big differentiators is transparent encryption; Home editions don't have any built-in support for encrypting data at rest, so if your laptop gets stolen attackers can take anything on the hard drive. My girlfriend has been dealing with the aftermath of this for a few weeks now (as if having her computer stolen wasn't bad enough), with constant attempts at various kinds of identity theft. It sucks. Encrypt your shit!
While Pro editions of Windows have had Encrypting File System for ages, it is per-file (or per-directory) and depends on you having a really strong password, since attackers can still pull the SAM and mount an offline attack. Since Win8 (for Pro; Vista and Win7 had it in Enterprise and Ultimate too) there's also BitLocker full volume encryption. I really wish Microsoft would make this available on all installs - they did for RT and phone, but not for PCs - but it's worth the upgrade to Pro. I also wish they would make it easier to use BitLocker without a TPM - it's entirely possible, you just need to change a setting most people don't even know exists, much less know how to find - but again, this is totally worth doing if you don't have a TPM.
Plus all the behind-the-scenes improvements made in Win8.x (high-entropy ASLR, RAM page combining, etc.), support for modern hardware (not just DX12, but also things like native USB3 support), and user-facing improvements (vastly improved multi-monitor support, settings and such synchronization across machines, etc.). Hell, some people even like some of the Store apps (and with Win10 bringing the ability to run them windowed on the desktop - as should have been possible from the start - a large part of the reasons to *not* use them goes away).