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Comment Re:If confirmed, does this make it realistic? (Score 1) 477

In a normal rocket, the speed you calculated is half the exhaust speed, not the speed of the rocket.

Power = (1/2)*(mass rate of fuel use)*(exhaust speed)^2
Force = (mass rate of fuel use)*(exhaust speed)

Power/Force = (exhaust speed)/2

Rockets are also machines that give a constant force at constant power, but both of these are constant because the exhaust velocity is constant. For the EM drive, if it really has no exhaust, then all these equations go out the door since momentum is not conserved and that means all calculations are inconsistent with our current knowledge of physics. "Over unity" no longer has any meaning.

I'm still waiting to see what happens.

Comment Re:Must be hiding (Score 3, Insightful) 205

Prior to the Mercury controversy, Uranus was found to be moving in ways not described by Newton's theory of gravity. Again, there are two solutions: our description of gravity is wrong, or there is an unseen ("dark") mass pulling on Uranus. In this case, it was dark matter, namely the undiscovered Neptune.

Both modified gravity and dark matter have been solutions to past conflicts between theory and measurement. There's no need to assume there's some conspiracy suppressing this or that idea.

Also, sometimes it takes a long time between a theoretical proposal to explain a mystery and direct detection. The neutrino was hypothesized in 1930 in order to conserve energy and momentum in beta nuclear decays. It wasn't directly detected until 12 years later in 1942. It took 49 years between the first papers proposing the existence of the Higgs boson and its discovery at the LHC. All we can do is search everywhere and be patient.

Comment I know: reading TFA is doing it wrong (Score 5, Informative) 499

Not only did the summary leave out the actual conclusion from the study (what was mentioned were stats before the masking) but also failed to mention the important finding:

Lerner dug into her data and came up with her own guess for the cause of the surprising results: women were leaving the platform after having one or two bad interviews. In other words, women, feeling discouraged, seemed to be just giving up on interviewing altogether. “Once you factor out interview data from both men and women who quit after one or two bad interviews,” she writes, “the disparity goes away entirely.”

Lerner’s findings here do correlate to some things academic research has also shown. She pointed to one study that found that after giving a scientific reasoning test to male and female undergrads and asking them how they fared, women underrated their own performance.

Both men and women perform better when two lessons are learned:
(1) Failure is not permanent, try again;
(2) Practice and training are valid ways of progressing in a technical field. The ability you are born with is not fixed for life.

Submission + - LIGO Reports Second Black-Hole Merger (quantamagazine.org)

An anonymous reader writes: Four months after announcing their epoch-making discovery of gravitational waves — ripples in the fabric of space-time — the Laser Interferometer Gravitational-Wave Observatory (LIGO) team and Virgo collaborators announced today and reported in Physical Review Letters that they’ve detected a second gravitational-wave signal. LIGO spokesperson Gabriela Gonzalez called it “a promising start to mapping the populations of black holes in our universe.”

Comment Re:free will IS bullshit (Score 3, Insightful) 386

Then there is no such a thing as free will, but rather an electrochemical process weighing the choice and the largest or smallest weight being preponderant.

The physical implementation of an abstract concept does not negate the abstract concept. Otherwise, there's no such thing as computation, just voltages and currents pulsing through printed circuit boards, signifying nothing.

Frankly free will does not exists and such study confirm it : our choice are dictated by our memory, education, past, and perception.

If our choices were not dictated by such things, they would be random. What else could we base our choices on?

In any case, the experiment in the TFA does not address free will, but an implementation detail of a mind. It's interesting, but not philosophically significant.

Comment Re:Classist (if that's a word) (Score 3) 84


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Comment Re:pointers & C (Score 1) 437

The "allocate in the constructor, clean up in the destructor" pattern ... is still just as error-prone (just fewer places for errors), and the fact that the destructor doesn't get called if the constructor throws isn't broadly internalized by coders (and is my least-favorite intermittent resource leak to run down).

I've come up with my own pattern (probably not original) for dealing with throwing constructors and I've been wondering if it's effective. Basically, write a separate cleanup() method that gets called by the destructor and the catch() block of a constructor:

    { // ... do stuff and acquire resources
        throw; // to prevent Foo instance from being used


{ // release any acquired resources

Comment Re:How Big an Improvement Are We Talking Here? (Score 1) 92

Not quite. There are very few algorithms that will see a substantial speedup on quantum computers, factoring numbers and simulating quantum systems being the big two. In fact, it wasn't until Shor's algorithm was discovered that physicists really took an interest in quantum computers since no one knew if there was anything a quantum computer could do better than a Turing machine. For general problems, you can only get a modest speedup over a brute force search on a classical computer. To find an entry in an unsorted database takes O(n) on a classical computer and O(sqrt(n)) on a quantum computer (Grover's algorithm). To get better results, the problem has to have some special property that is amenable to encoding in a quantum system (the quantum Fourier transform in the case of Shor's algorithm).

For now, it seems that quantum computers won't help with NP-complete problems.

Comment Re: Need to prove intent (Score 1) 308

If the subpoenaed material was destroyed, erased, or flushed before the subpoena was received, you're fine. It is the state's burden to prove you destroyed the materials in order to obstruct justice (that is, after receiving the subpoena or other court order) or that you are lying about not having them.

Comment Re:watched a movie yesterday (Score 3, Informative) 61

You're right: the LHC beams are made up of separate bunches of protons. These bunches only collide at the 4 detectors. If they collided anywhere else, there wouldn't be anything to detect the products of the collision, so that collision would be a waste. Until the collision in the detectors, the protons moving in opposite directions are kept in separate beam lines: http://lhc-machine-outreach.we.... Here's a look inside the beam pipe: http://lhc-machine-outreach.we...

The time between collisions is 25 nanoseconds, meaning there is 25 feet between each bunch (light travels at about 1 foot per nanosecond). When two bunches collide, there are only 20-30 proton-proton collisions because the protons are so small compared to the size of the bunches. By the time the next bunches arrive at the collision point, the debris from the first collisions are completely gone from the original collision point (about 25 feet away in all directions).


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