No, you already input energy to separate the water and the salt. Remixing them will release part of the energy which could be harnessed, but inevitable losses in conversion will make it better to just use your original energy if you didn't need the fresh water. One nice thing about this article is that they explicitly state the most important point...that it is impractical to use this method in the only context where it would have potential for significant impact which is in the mixing of fresh water rivers with ocean water.

At one level, they are right that unreproducible results are usually not fraud, but are simply fluctuations that make a study look promising leading to publication. But raising the standard of statistical significance will not really improve the situation. The most important uncertainties in most scientific studies are not random. You can't quantify them assuming a gaussian distribution. There are all kind of choices made in acquiring, processing, and presenting data. The incentives that scientists have are all pushing them to look for ways to obtain a high profile result. We make our best guesses trying to be honest, but when a set of guesses leads to a promising result we publish it and trust further study to determine whether our guesses were fully justified. There is one step that would improve the situation. We need to provide a mechanism to receive career credit for reproducing earlier results or for disproving earlier results. At the moment, you get no credit for doing this. And you will never get funding to do it. The only way to be successful is to spit out a lot of papers and have some of them turn out to be major results that others build on. The number of papers that turn out to be wrong is of no consequence. No one even notices except a couple of researchers who try to build on your result, fail, and don't publish. In their later papers they will probably carefully dance around the error so as not to incur the wrath of a reviewer. If reproducing earlier results was a priority, then we would know earlier which results were wrong and could start giving negative career credit to people who publish a lot of errors.

Problem is they don't care about quantum computing. What the authors of this proposal mean by 'the national interest' is 'does it enhance the power and prestige of the wealthy interests that currently control much of the US government and economy'. If they had the capability to think about it, they would realize that quantum computing is in their short term interests (it would allow them to read the rest of the global communication that they are not already intercepting), but not in their long term interests (because eventually everyone will switch to quantum information passing for which interception is detectable). But they actually don't know enough to care about quantum computing. They simply want to rule the world and they view scientists as a tool to use toward their ends.

We can be pretty sure that there are new fundamental laws that we don't yet know. The phenomena ascribed to dark matter for example are clearly physical phenomena and there must be fundamental laws that describe them. It is not at all clear that we have exhausted possible means to learn about new fundamental laws. There are improved dark matter searches going on all the time. Gravity wave detectors are likely to find something in the next few decades opening a new window on the universe, and there is a reasonable chance that LHC will show new physics beyond the standard model. It has been slow going compared with the first half of the 20th century, but progress on fundamental laws has not ground to a halt.

You may be hinting that discovery of new fundamental laws may not be very useful for building new technology. There I would probably agree, at least in the next century of two. But that is very different than the claim that we will not discover any new fundamental laws. The deep claim that many people seem not to have accepted yet is the one made by Sean Carroll in his series of blog posts explaining that the physics of everyday life is already understood. 'http://www.preposterousuniverse.com/blog/2010/09/23/the-laws-underlying-the-physics-of-everyday-life-are-completely-understood/' In his sense, you are right. This is it. We will always be describing our world using concepts of electrons, photons, neutrons, and protons etc. interacting by the four known forces. However, simpler calculating methods may well be possible, like the ones proposed in the original post, which can dramatically change our abilities to predict the outcomes of known fundamental principles.

This comment sounds like Elon Musk himself. There is even a Freudian slip 'we'. http://www.popularmechanics.com/how-to/blog/elon-musk-on-spacex-tesla-and-why-space-solar-power-must-die-13386162

Yes, you are right. I made a basic mistake. I did 1 m/s^2 rather than 1 g. 350m/s at 1g has a turn radius of 12.2km. Much more manageable. That also gives you 3.7cm misalignment over a 30 m section for 1g which will be much easier to maintain. However, you probably want less than 0.1g rapidly varying acceleration, so alignment at mm or better tolerances may still be required. I think high speed rail are already aligned to mm tolerances without active feedback. It seems like a critical cost question will be whether a good suspension and good static construction methods can maintain adequate alignment or whether they need active feedback. Seems the active feedback would be expensive and difficult.

Yes, evolution has created intelligence without knowing how it works, so it seems it must be possible for us to do it again...although we can't really wait around to develop it by selection on random variations.

It also seems that we easily underestimate the number of kinds of intelligence that may be possible. Although it is possible that human intelligence is a good example of a kind of general intelligence that is evolutionarily convergent and other kinds of intelligence will be similar (although maybe different in degree by being faster or less prone to mistakes (or slower or more prone to mistakes)); it seems more likely to me that human intelligence is one of many ways to understand, and many different kinds of intelligence could be developed depending on which of many different tasks it is being optimized to perform.

So for example, I wouldn't focus on natural language capability if I were working on building AI. And hence I think the Turing test is mostly irrelevant. It seems that language is an unbelievably complicated approximation scheme that humans developed to communicate while avoiding dealing with the complexity of their surroundings. Science developed largely to the degree that we became able to use experiments and mathematics to help us find precision amid the ambiguities involved in human language. I would probably focus on building a system that could simulate its environment, using approximate models to simplify the complex parts to make it computable. Then give the system some kind of way to represent goals and simulate ways to approximately reach those goals. Then try to try the way that seems most promising and learn from mistakes. This is the path that robotics and video games are already going. However the alternate route of trying to understand natural language and use the massive base of human understanding as a starting point for artificial intelligence will continue to be an attractive avenue also.

One of the great open questions about the future of humanity is which will happen first: A) we figure out how our minds are able to understand the world and solve the problems involved in surviving and reproducing. B) we figure out how to build machines that are better than humans at understanding the world and solving the problems involved in surviving and reproducing.

I think it is not at all clear which one will happen first. I think the article's point is exactly right. It doesn't matter what intelligence is. It only matters what intelligence does. The whole field of AI is built around the assumption that we can solve B without solving A. They may be right. Evolution often builds very complicated solutions. Compare a human 'computer' to a calculator doing arithmetic. Clearly we don't need to understand how the brain does this in order to build something better than a human. Maybe the same can be done for general intelligence. Maybe not. I advocate pursuing both avenues.

Since reading the paper on the proposed Hyperloop when it was posted, I have been wondering what piece of the research and development will turn out to be the most difficult. Everyone focuses on the costs and political difficulties of getting this actually built. But at least on /. we should be able to contemplate the engineering without worrying about the biggest problems for these systems which is that foolish humans have to build and use them. :)

It seems to me that maintaining alignment of the tube might be the most difficult challenge. To maintain accelerations below 1g at 350 m/s (782 mph) you have to have a radius of curvature more than 122 km (a=v^2/r). That means the variation from a straight line of only 3.7 mm over the 30 m between pylons will produce 1g. And it takes 0.085 seconds to travel this distance, so it has the potential to produce one hell of a bumpy ride. Now I think they could maintain alignment of a few microns over 30 m and a good suspension could probably remove most of the bumps, but it could be a tough challenge. Since day/night temperature differences and many other things will probably move the pylons on these scales, they are going to need active feedback to maintain alignment.

The alignment will need to be measured and corrected over scales up to at least tens of kilometers. What kind of a system would you use to measure alignment with accuracies of microns over tens of kilometers? What kind of actuators would you use to position a steel tube 2 cm thick and 2.3 m in diameter with accuracy of microns? What failure rate can be tolerated with 25000 pylons? How much would the tube bend if one pylon had its actuators fail or if a semi truck ran into a pylon?

When I first thought of how to build a prototype for this system, I thought of using a circular loop since it would allow a single induction motor to accelerate a cycling capsule many times until it reached full speed, just like a cyclotron. But then I calculated the radius necessary to maintain moderate accelerations, and realized how straight this tube is really going to have to be. Maybe they can use a circular loop to test low speed operation, but even a circle of 10km radius can only go to 70 m/s (158 mph) before going above 1g. In a 1km radius circular loop at 350 m/s you have 122g. So the high speed tests are going to have to be in a straight test facility with linear motors capable of taking the capsule up to full speed.

That is a very interesting result. Their first measurements of the positron energy spectrum are consistent with super-symmetry ideas about dark matter collisions creating positron-electron pairs. If it turns out to be right, it will be the first non-gravitational detection of dark matter. But there is not much experimental support for the super-symmetry ideas being used to connect dark matter with positrons, and there are other possible sources of the positron spectrum at the current accuracy. So we'll see. It is great to see they have some results...this experiment has taken a long time and a lot of money. But when you introduce a much more precise way to measure, it usually turns out to be worth the cost and effort in the end.

Economist tech news seems to always have these breathless descriptions of new technologies that will change everything without bothering to understand the underlying science. Why let facts get in the way of a story that sells? At the root of it, I think some economists realize that the model of continuous exponential growth used in their models depends on continuous revolutionary break-throughs in energy technology and basic materials. Since the recent reality has only had incremental changes, they feel pressed to make up revolutions in hope that it will save their models.

I think you misunderstand the situation with our understanding of gravity. We already have a theory that describes everything we have been able to observe on scales smaller than a galaxy. This is very different than magnetism where we were using magnets for hundreds of years before we had an adequate theory. My point is that solving a theoretical inconsistency (like quantum gravity) has no clear practical consequences when there are no observations that need to be explained.

Nuclear reactions are already well within the range of energy scales that are fully described by our current theories. You have to be at truly exotic energies that haven't existed since the big bang (except in very rare cosmic rays or in our future particle colliders) before you might find deviations from our current theories.

Many of you seem focused on Star Trek. Does it not seem a little odd that it is fictional entertainment rather than experiments that are being used to decide what is physically possible? No one has ever detected anything moving faster than the speed of light. A hint of neutrinos going 1 part in a million faster than light was treated as a major anomaly this past year, until it was found to be an experimental error. There is no reason whatsoever to expect warp drives...except the human attraction to wishful thinking. And there is also no reason to think that wormholes exist or that we would be able to manipulate them.

There are many cases like this. I mentioned the human brain. But there is no evidence to suggest that superconductivity is not simply many body quantum mechanics. Unsolvable at the moment, yes. But it doesn't show any deviations from current theory in a fundamental sense.

The only way to manipulate gravity that anyone has found is to move mass around. Similarly, we manipulate electromagnetism by moving charges around. But we don't have a theory of quantum gravity precisely because we have not found any ways of moving masses that doesn't agree with the predictions of general relativity. In short, there is no evidence of any effects of quantum gravity that could be exploited for any of the Star Trek like manipulations of gravity. For E&M, the situation was exactly the opposite. There were a hole bunch of observed phenomena before there was any useful theory. The last two examples (superconductivity and biology) fall into the latter part of my comment...There will be major revolutions. But they will not be in fundamental physics. They will be in our ability to use our known theories to predict the behavior of complex systems.

You are after increases in our experimental capabilities, but mbkennel is talking about something else. The materials and processes relevant to our lives on earth are largely understood at a fundamental level. That is a major difference that isn't going to be changed by more precise experiments. Say we can measure collisions at 500 TeV rather than 8 TeV currently. It may produce a breakthrough in particle physics. But what materials and processes relevant to our lives will be revolutionized? (Now of course we can't predict the behavior of many things relevant to our lives, and there are major breakthroughs available there, but it won't be in fundamental physics).