Prototype Volvo Flywheel Tech Uses Car's Wasted Brake Energy
Same for the Toyota Prius: unless you press the brake, regenerative braking is not engaged. So with neither pedal depressed, the car is just coasting. In fact, because the Prius is so aerodynamic, it coasts 'faster' (by which I mean it slows down due to air friction more slowly) than most other cars, so you can coast for quite awhile before needing to touch the gas again. In fact, I've actually been in situations where I was over-taking other cars while coasting...
Physics Forum At Fermilab Bans Powerpoint
Indeed, the best talks will use both for what they are good at: a pre-arranged slidedeck for images and complex graphs that cannot be hand-drawn; and a chalkboard/whiteboard for developing an idea, skething a graph, deriving an equation, or discussing back-and-forth.
I will note that many conference rooms are poorly designed in this regard. They have the screen for the projector on a slow motor, and when the screen is down it entirely or subtantially covers the chalkboards/whiteboards. This makes it cumbersome to jump back and forth between them. If you want to encourage people to use both (and we should), then the screen should be offset and there should be a large whiteboard always unobstructured and available for the presenter to draw on. (Another pet peeve is that the whiteboard markers in the room will often be dry, or the chalk missing; which makes the whiteboard/chalkboard useless.)
Interview: Ask Richard Stallman What You Will
SoylentNews is a new site (based on SlashCode, in fact) that is complementary to Slashdot in that it seems to be targetting sci/tech discussions.
A New Car UI
Parenthetically, (geek alert) the controls on TOS Enterprise, with their distinctive shapes, seemed a LOT more practical to me for an environment with lots of tipping and juddering in combat, as opposed to the all-touch-screen controls in later generations, which required that you keep your hands in contact with the control surface in a potentially hostile environment and watch your hands manipulate virtual buttons and switches, when you should probably be looking at something else.
The "Star Trek: The Next Generation Technical Manual", on page 33, when describing the touch-panels, says: "Also incorporated into this layer is a transducer matrix that provides tactile and auditory feedback to the operator..." They don't elaborate on what this 'tactile feedback' might be like. At a minimum it would presumably indicate (e.g. via a vibration) that a button was pressed. Some fans have hypothesized that the panels perhaps incorporate miniature versions of the force-field technology used throughout the ship: so that even though the panel looks flat, you can actually 'feel' the buttons/layouts as you move your hands around; and of course this tactile response updates as the layout does. (This is supported by the fact that in Voyager, when Tuvok is blinded he is able to activate a "Tactile mode" on his workstation, implying that all panels have the ability to generate tactile feedback.) Thus, the TNG-era touchscreens could have had substantial amount of tactile control.
The reason I point this out is that the creators of a sci-fi show in 1991 could easily imagine that a flat-panel interface would benefit substantially from tactile feedback. The fact that modern vehicle UI designers can't understand this is thus rather ridiculous.
Graphene Conducts Electricity Ten Times Better Than Expected
You are correct that using graphene or carbon nanotubes (which are close cousins) only for the wiring wouldn't gain you much; especially since large resistances can arise from the junctions between two conductors/materials.
People are certainly investigating how to turn graphene and nanotubes into transistors. There have been demonstrations of using an applied voltage to mechanically 'kink' a nanotube so that its resistance changes. Thus it can be used as a non-volatile memory element. (The kinking is reversible and fast.) Others have looked into ways to 'dope' graphene by controlling what material it is sitting on top of (which changes its electrical properties, similar to doping atoms into silicon). Things like this can be used to make transistors out of these carbon nanomaterials; and in principle to do it in a way where the conducting carbon network is unbroken.
Of course, the devil is in the details. We've seen demonstrations of many pieces of the puzzle, but turning it all into a technology (where you can build it all easily on a single substrate, in a scalable way, etc.) is still a ways off. But there is at least a chance these materials will pan out.
P.S.: Don't let this comment distract from the legitimate outcry against Slashdot Beta.
Military Electronics That Shatter Into Dust On Command
Yeah the Slashdot comment-box has some longstanding issues, like support for displaying source-code/html properly, or unicode support in general.
The devs should really consider coding an improvement to Slashdot that addresses these concerns. Some kind of 'Slashdot beta'. I'm sure it would turn out great...
Military Electronics That Shatter Into Dust On Command
What really scares me is the thought that the editors haven't really even noticed.
One of the things that has always surprised me (even bothered me a bit) about Slashdot is that the people running the site do not appear to actually use the site. The editors don't routinely participate in discussions. We occasionally see a comment from an editor, but they are certainly not among the top commenters. (Even CmdrTaco's comment history was surprisingly thin...) These are people who are paid to be involved with the site. I know they have other duties, and perhaps being an employee makes participating in the community less fun. But on the other hand, if your job is to manage an online community, I would expect to see more involvement.
I sometimes wonder whether the editors actually read through Slashdot comments at all, or whether they just queue up some stories and then work on something else.
I'm guessing that by now they've noticed the firestorm of hate, since it's being injected into the comments, firehose/story-submissions, polls, via email, etc. But even so, I feel that ultimately the disconnect between what the Slashdot community wants, and what the powers-that-be are planning to provide, is that the people running Slashdot are not Slashdot users (much less contributors). So they do not even realize why we hate the beta so much. To an outsider, one commenting system and another might seem pretty much the same. It might seem like we're complaining over minutia. But to someone who is trying to participate in the fast-paced and highly technical discussions that erupt on Slashdot, the commenting system is paramount. Ruin it, and you've killed the site.
The Standards Wars and the Sausage Factory
I agree that the owners of Slashdot are free to take it in another direction if they want. Presumably what they desire is more money, and they believe the redesign is a way to increase ad revenue. So far so good.
In this case, however, I believe their strategy is not a good one. If you alienate the commenters, then they will leave, and all that will be left is a stream of story digests with links to other sites. The bulk of their readership (all those people who come to Slashdot but don't comment on stories) will go to other sites (there are plenty that do a better job of finding and organizing links to interesting stories). The only differentiator that Slashdot has is its vibrant and intellectual community, which leads to interesting discussions, which in turn justifies actually visiting the site. Once the commenters leave, your revenue stream (ad impressions) will go away.
The problem is, most slashdot contributors I don't think click on the ads. So frankly as a community, you're not that valuable.
There is some truth to this. Slashdot users are probably less likely to click on ads than the average person. We are probably more aware of advertising tactics, and may thus avoid being influenced (to the extent one can). Slashdot users are probably more likely than most people to use ad-blockers. On the other hand, Slashdot users occupy a huge number of key decision-making posts in all the major tech companies. Even 'lowly' employees can have a huge impact on what their employer spends money on. I would also note that an ad is not necessarily a failure if no one clicks on it. One of the main purposes of advertising is awareness and branding. If you see ads for a given company on Slashdot, you will subconsciously become aware of them, making it more likely that you will consider them when making your next purchase. No clicking required.
I fully admit that it is difficult to quantify the 'value added' of advertising to the unique Slashdot community. I would hope that Dice has made this case to their ad partners; I guess it wasn't enough?
And what's wrong with that? They have ongoing costs in terms of servers, IT support, and the moderators. Word is for the most part the Slashdot revenue stream has been shrinking for Dice, which means they'd be bleeding money.
Actually it's not clear to me that's the case. The things I've read indicate that revenue coming from Slashdot is decreasing with time. But this isn't the same thing as saying that Slashdot doesn't generate enough revenue to pay for operating Slashdot. From what I can gather, Slashdot is a net money-maker... it's just not making enough money, and the owners want to make more. (If someone has better info, please share!)
Is Intel Selling Bay Trail Chips Below Cost?
The nascent "AltSlashdot.org" effort hasn't settled on a name yet. The name will be changed, and will avoid all trademark issues. The plan is to have a community vote on the new name; several punctuation related puns have already been suggested.
The hardest part, of course, is building up enough momentum fast enough for such a large community to transition. It may or may not work...
Amazon's Double-Helix Acquisition Hints At Gaming Console
This is probably right. We are all looking at the beta redesign as an obvious failure. But the people in power may well believe that overall the loss of the community of commenters will be "worth it" to transform the site into a higher-traffic (and thus higher-profit) news aggregator. On some level this makes sense: the active community of Slashdot commentors is far smaller than the size of the people who just visit the site. So if one can piss off the commentors but increase web traffic overall, then it's worth it.
The problem with this logic is that all of those visitors only come to the site to read (if not engage in) the commenting that goes on. Really the (relatively high-quality) comments are the only thing that differentiate Slashdot from any other website. Once you make commenting/discussion more cumbersome, it will go away, and all you will be left with is the Slashdot "brand". But does that brand really have any weight? It only does with the small community of tech-enthusiasts that you just drove away from your site. It's not like the average person is going to see a "friendlier jazzier Slashdot" and immediately think "Wow, finally a Slashdot I can enjoy!".
If you look into the financial details, it appears that Dice considers Slashdot a loser:
... advertising revenue has declined over the past year and there is no improvement expected in the future financial performance of Slashdot.
Note that this isn't saying that Slashdot's ad revenue isn't enough to pay for operating Slashdot; merely saying that the ad revenue is falling with time. They are no doubt desperate to increase profits. It's actually quite possible that Slashdot's ad revenue is undervalued (because it isn't taking into account that many Slashdot users hold key positions where they influence what tech is purchased by companies, friends come to them for tech advice, etc.). But overall the idea that they can increase ad revenue by revamping the entire site is a bad gamble: the community will disappear in a flash, and ad revenue will drop to zero.
Ultimately, Dice management appears willing to take the gamble. It is one they will most likely lose, and we will lose Slashdot in the process. But they won't care much, since Slashdot as-is just isn't pulling in that much money. It's a sad reality that even a community as big and stable as Slashdot (generating constant ad revenue) is still too small/niche to satisfy their money-lost. Our last hope may lie in efforts to build a new site that we can migrate to (e.g. AltSlashdot.org).
Amazon's Double-Helix Acquisition Hints At Gaming Console
Actually, Slashdot alternatives should avoid having a name too closely tied to "Slashdot", so as to avoid trademark disputes down the road.
In fact, Slashdot has actually used the "backslash" brand. If I recall correctly, the original idea was for that site-section to house various 'about slashdot' material, but currently there seems to be nothing there. The tag "Slashback" has also been used on Slashdot and so should be avoided.
FYI, there is burgoning effort to build a replacement at AltSlashdot.org (final name pending a community vote). If you're interested in having a replacement exist, then consider contributing to one of these efforts.
Build an Open-Source Electric Car In About One Hour
BTW, you should consider coordinating effort with others who are attempting roughly the same thing. E.g. user Okian Warrior has registered AltSlashdot.org and is planning to put a slashcode install there.
In fact, there may be more parallel efforts out there. On the one hand, competition may be good (let the best replica win!); on the other hand, migrating a community the size of Slashdot is no small task, so we may only get one shot at this.
Also, for legal/trademark reasons, you may want to consider a name that doesn't include "Slashdot" so overtly. E.g. tpaudio has suggested "Plusdot". Another idea (mine) is to call it "divergence" or "divergence operator"... the logo would be the mathematical form of divergence, i.e. nabla symbol followed by a dot (which looks like an augmented "slash dot").
Google Launches Voice Search Hotword Extension For Chrome
I agree. The voice-to-text is remarkably good: definitely at the point that it has become a tool and not just a toy. (I won't say that it never makes mistakes, but it's accurate enough that you can dictate a text message and only have to make a small number of fixes, making it overall faster in many cases.) The Google Now features also work well (asking relatively free-form questions).
However, the 'embarrasement factor' still looms large: I don't want to use the functionality where it might disturb other people (e.g. at work), and I'm even self-conscious using it when walking around in public. (Yes, it remains ironic that we feel weird talking into our phones.) I also avoid using when my wife is in a nearby room, because of the "What did you say? Are you talking to me?" factor. And of course, I usually don't want to broadcast my activities for all to hear. As a result, I'm not conditioned to use the feature, and I forget to use it even in cases where it would make sense (e.g. home alone).
I guess what I'm saying is that the adoption of these technologies might well be more limited by social convention, rather than limitations in the tech itself. I'm not sure if this is an intrinsic aspect of humanity (that on average people don't like talking to technology, despite what sci-fi has long predicted), or whether this is purely generational, and the next batch of users will be completely comfortable speaking commands to their computers/phones/etc. (in which case, the tech will no doubt have to improve; e.g. in order to only respond to the assigned user's voice).
Pinholes and Plastic Wrap Make Solid Walls "Transparent" To Sound
Well, TFA suggests:
The research has potential uses in creating security barriers that permit voice communication to pass through, and in developing types of sound-based microscopes that could find application in research laboratories and medical practice.
The scientific paper further notes:
Such a high concentration of acoustic energy into a small hole of radius enables sensitive detection of acoustic signals with subwavelength resolution ... the present work not only opens the way to the efficient realization of [near-field acoustics] in fluid ultrasonics and underwater acoustics, but also to the analogous realization in solid-state ultrasonics.
More broadly, results obtained for one kind of wave behavior often have implications for other kinds. I.e.: results in controlling acoustic waves sometimes have implications in controlling/sensing light-fields, or radio waves, or even more esoteric things like electron beams or neutron beams (which are also regulated by wave equations).
One-Time Pad From Caltech Offers Uncrackable Cryptography
This work seems to be based on this high-profile paper from 2002:
Ravikanth Pappu, Ben Recht, Jason Taylor, Neil Gershenfeld Physical One-Way Functions Science 2002, 297 (5589), 2026-2030, doi: 10.1126/science.1074376
Abstract: Modern cryptographic practice rests on the use of one-way functions, which are easy to evaluate but difficult to invert. Unfortunately, commonly used one-way functions are either based on unproven conjectures or have known vulnerabilities. We show that instead of relying on number theory, the mesoscopic physics of coherent transport through a disordered medium can be used to allocate and authenticate unique identifiers by physically reducing the medium's microstructure to a fixed-length string of binary digits. These physical one-way functions are inexpensive to fabricate, prohibitively difficult to duplicate, admit no compact mathematical representation, and are intrinsically tamper-resistant. We provide an authentication protocol based on the enormous address space that is a principal characteristic of physical one-way functions.
Basically, they create a slab of epoxy with a bunch of glass micro-spheres randomly distributed within it. When you shine light through it, the multiple refractions/scattering events lead to a complicated path for the various light beams, which interfere to generate a complicated light-speckle pattern on the other side. This multiple-scattering process is of course deterministic, but in practice it is so complicated that it is not feasible to reverse-engineer the internal structure of such a material. (In fact, the method exploits coherent scattering, and because the light-detector can only measure the amplitude (and not the phase) of the scattered light, the problem is formally 'ill-posed': there is no way to invert the coherent scattering data to obtain the material structure. Instead such problems can only be approximately solved with iterative processes; this can be made arbitrarily difficult by increasing the number of scattering entities (glass beads in this case)...) This is analogous to mathematical one-way functions: in principle you can crack them, but it takes an infeasible amount of time.
Ultimately the 'randomness' (uniqueness of a slab) comes from the inital preparation of the slab: you're basically 'freezing in' the random Brownian motion of the micro-particles. Thermal noise is a pretty robust source of randomness.
These slabs are neat in the sense that you can use them to generate multiple pads. A different illumination condition (incident angle, or light pattern) generates a new one-time-pad (see the paper for a discussion of 'how different' the illumination condition needs to be in order to yield a uncorrelated/unique one-time-pad), so one idea is for people to carry a single physical token and use it to generate different OTPs for different communications channels they care about.
These schemes are not without their downsides, of course, but it's a neat idea to use a physical structure (rather than mathematical function) to generate pseudo-random numbers. (Thes slabs don't require a battery to maintain their state; one could image secure ways of generating two identical slabs at fabrication time, and then giving them to the two parties; etc.)
Physicists Attempting To Test 'Time Crystals'
Possibly I don't know what is meant by perpetual motion.
Well actually I think the term "perpetual motion" isn't particularly helpful. You're right that it's easy to imagine systems that undergo a certain periodic motion without end, as long as they are not disturbed (no energy extracted). Some people call that 'perpetual motion'. Other people might reserve the term 'perpetual motion' for discussions of non-ideal systems (i.e. real systems in our universe), which are subject to incidental effects (like friction). For real systems, there are going to be additional channels of interaction that allow energy to move into other systems, and thermodynamics (entropy wants to increase) thus guarantees that these channels will be used, preventing cyclic/periodic motion from being endless. (One can imagine gas atoms randomly moving around until the end of time, normally that random motion wouldn't be called 'perpetual motion'.)
However, if left alone, my understanding... is that it will keep orbiting forever assuming the orbit is stable and is left alone.
In Newtonian physics, this is true: the orbit will continue forever. (An unremarkable example of perpetual motion. Unfortunately only theoretical since our universe doesn't strictly obey Newtonian physics.) In relativity theory, the orbiting bodies will emit gravitational waves, which means they are slowly radiating away energy. The orbit will decay and the system will eventually end up in a minimum-energy state where there is no orbit/motion. (The ambient random energy of space-time will have been increased: hence entropy increased.)
I believe there are solutions to the equations of general relavitity which include time-oscillatory behavior but do not emit gravitational waves. (Wikipedia says that an ideal spherically-symmetric pulsating mass should not.) But these kinds of ceaseless motion are different than what is being proposed in TFA.
When I said this looked like a perpetual motion machine and that was nothing that extraordinary that is what I was referring to... stable systems that don't degrade assuming you leave them alone.
Right. And if that's all that they were talking about, it wouldn't be that impressive. E.g. one can imagine putting an ion in a magnetic trap, giving it a small push, and watching it orbit around through the trap without end. Call it perpetual motion if you like. (In reality it will be radiating electromagnetic energy and slowing down imperceptibly as a function of time.)
The novel thing about these 'time crystals' is that they would exhibit motion and yet be in a minimum energy state. There would be no way to extract energy from their motion. This also means that the motion would be truly perpetual in the sense that no incidental process could cause the motion to stop, since there is no excess energy to be radiated away. This is the novelty of the new states (assuming they actually exist).
Physicists Attempting To Test 'Time Crystals'
Here's my understanding (I'm a physicist though not in a field at all related to the described work):
As usual, the summary and the article somewhat mis-state the interesting part. They talk about 'perpetual motion' but there are lots of examples of things that move seemingly without end: e.g. a planet orbiting a star. However if you think about it a bit more, you'll realize that those kinds of motion can't be used to get "free energy" and actually are not even perpetual. If you try to extract energy from some kind of bound system that exhibits motion, you decrease the energy of the system and alter the motion. So you can extract energy from a planetary orbit (in principle), but then the planet will have less energy, and orbit more slowly (its orbit will decay). As other posters mention, all kinds of natural processes inherently perform this kind of "energy extraction": e.g. random collisision with space-dust, or tidal interactions between planetary bodies, will slowly alter these 'perpetual' orbits. Even if you imagine a highly idealized system (perfectly rigid objects orbiting one another in perfect vacuum), we have reason to believe that such a system will radiate away energy (slowly) by emitting gravitational waves.
What this all amounts to is saying that the system has some 'extra energy' that could be extracted. In physics we would say that the system is not in its ground state, or "minimum energy state". This is the key phrase that the quoted physicists use which the article doesn't properly explain.
The idea is that a system in its ground state will have lost all the energy it can possibly lose. There is no extra energy left. And, conventionally one would assume that a system in the ground state would no longer exhibit any kind of motion: because any motion is extra energy that could be extracted, obviously. So an idealized orbital system has motion, but is not in the minimum energy state. What Wilczek is proposing is that he's discovered kinds of systems which exhibit motion in their ground state. In other words, the system oscillates as a function of time, and yet one cannot extract energy from this oscillation. Cool!
The analogy to crystals is this: as you cool atoms, they vibrate less and less, and eventually they settle into their minimum energy state. This state is usually a crystal, where all the atoms are frozen into perfect rows. This is the minimum energy state. Interestingly, at high-temperature the system was spatially homogeneous (a gas has atoms all over the place), whereas the ground state has spontaneously broken space-translational symmetry: the atoms exist in well-defined positions and don't occupy intervening points. Thus the ground state spontaneously breaks a symmetry (space-translation). Wilczek's proposed states, if they really exist, would upon cooling to their ground state (no excess energy left) settle into an arrangement where they are in motion. Thus along the time axis the system is not constant/homogeneous. The system has spontaneously broken time-translational symmetry. Hence this is like a crystal along the time axis: a 'time crystal'.
I'm not qualified to say whether this is right or wrong. It would be exciting if true. But it doesn't seem to violate any known laws (e.g. you can't use it to violate conservation of energy, so no 'perpetual motion' in the 'free energy' sense), so it seems possible that these states could exist.
Terrible Advice From a Great Scientist
In your analogy, you're talking about a very high-level split that can be done cleanly. One person does the creative work of coming up with a game design (storyline, play control, etc.) without worrying about the underlying implementation details. Then another person can certainly do the engineering and coding work to implement that.
But it should be obvious that for some other problems this won't work. For example, it doesn't make sense to try and split the coding into a "creative coder" (who knows nothing about programming) and an "implementation coder" who turns the creative's ideas into actual code. The creative would toss out nonsensical ideas (like "instead of using vectors, why not use genetic algorithms?"), and then the implementer would have to explain why all those ideas are silly... or else they would just have to ignore the creative type and simply code something that makes sense.
In other words, generating good source code requires someone who knows enough about programming that they can see creative solutions. Their intuition is not separate from their programming talent: their intuition is based upon years of training and experience with source code, math, engineering, and so forth. That's where the good ideas come from.
Coming up with good scientific ideas is similar. Analysing scientific data even moreso. It's only once you have a deep, subliminal understanding of the important concepts that you're going to make substantive progress. Whether a deep understanding of math counts as an "important concept" depends on the field, of course... but I would argue that for science generally, the more mathematical know-how you have, the more informed and powerful your ideas will be.
Elon Musk Lays Out His Evidence That NYT Tesla Test Drive Was Staged
Unless these logs were doctored (unlikely), then Broder lied. However, the one claim of Broder's that Tesla doesn't try to debunk is the loss of charge from overnight cold. Looking at the graphs, somewhere around mile 400, there is a sudden drop in charge from ~45% to ~38%, with a corresponding drop in estimated range from ~80 miles to ~20 miles (the two are not linearly related, presumably because of the intrincacies of the charge/discharge curve being nonlinear). This seems to correspond to what Broder said, that by letting the car sit in the cold, it lost 2/3 of its range.
This is the one negative thing that may have been true in the NYTimes story. Of course, now that Broder has ruined his credibility, even that must be called into question (did he leave it running in a parking spot for a few hours with the heater blasting? ... actually there is a spike in the 'cabin temperature' right at that point...). As someone actually interested in electric cars, that's the kind of question I would like a proper answer to. So, it would have been nice for Tesla to address it (beyond just saying that they have lots of sales in frigid countries).
Ask Slashdot: Why Is It So Hard To Make An Accurate Progress Bar?
Predicting the future perfectly is impossible, but coming up with reasonable predictions is do-able. We do it all the time (from the mundane "I'll be there in 10 minutes" to the more general "science"). Throughout this thread I've seen all manner of explanations given for why it's hard. But I think the real explanation is not "it's hard" but rather "it's not worth it".
Consider an analogy. One might say that building a backup application is impossible: files could disappear halfway through a backup, there could be multiple versions of a file, multiple copies of files could exist, network connection could be lost, etc. But none of this makes it impossible, it just means that one has to design solutions that take into account all of these factors (deduplication, versioning, error recovery, etc.). It's a solvable problem, and one that is solved (to varying extents) in existing backup software. We go to the effort because it's important that backup software work properly.
Similarly for a progress bar. If we really wanted to, we could have an API where the OS monitors the computer's performance, and has ready-to-use metrics for "average disk copy speed" and "average download speed" and so on (even with stats on variation by type of task, time of day, temperature of CPU, etc.). Then when a progress-bar widget pops up, it polls this API, and multiplies a pre-computed task list (# of bytes to download, # files to copy, etc.), and comes up with an estimate. Then it monitors the actual progress, and continues to refine the estimate (averaging over appropriate timescales so as to ignore fluctutions). End result is that the time estimate for a progress bar would be quite accurate most of the time (and when it started getting it wrong, it would be an immediate hint that something went wrong). GPS navigation software is actually a good example of this: it appears to multiply miles travelled*speed limit along the route, add in some padding for usual delays (stop signs), and ends up with an estimate that is remarkably accurate. (Of course it can't account for complete unknowns, but that's fine.)
But is it worth all that effort?
My point is: it could be done. The reason it isn't done is because it's usually not worth it. Or at least, programmers don't think it's worth it. I would personally love to have accurate and useful progress bars in all applications. But, crappy progress bars are not the end of the world... and ultimately someone writing an application probably doesn't want to spend a lot of time refining a progress bar that users only see for 10 seconds every couple of weeks. It's not worth their time when there are so many other things that need fixing. And I would rather an application that is robust in terms of saving data but innacurate in estimating save time... rather than an application that knows exactly how long it will take to create a corrupted file on disk.