When an essay or article has statements ike this:

                  A black hole is therefore a region of space that is totally, utterly dominated by the force of gravity.

It's clear the author knows little to nothing about physics. The physics _inside_ a black hole is local and can be quite normal: there's no reason to think it's _not_ normal physics. The definition of black holes involves the net effect of gravitation _outside_ the black hole, with a net escape velocity greater than C. Normal physics inside a black hole itself is critical to the "cyclic" models of the universe, where the gravitational mass is sufficient to draw the mass of the closed universe back and initiate a new "Big Bang". According to this model, the universe itself is one large black hole which we live inside. That's quite difficult if we're in a region of space that is "totally, utterly dominated by the force of gravity".

Some of the theoretical difficulty and potential for weird physics comes in observing the internal physics from outside the black hole. There's potential for a distinct set of physical laws, because it's effectively isolated and we can't observe the inside from the outside. But even those physical laws seem to obey angular momentum and charge, which can be be observed from outside the black hole itself much as the black hole's net gravity can be observed from outside.

Finally, there is no compelling reason to believe that there is _ever_ such an object as a completely spherical, detectable black hole, which is what this poorly researched article keeps talking about. Extremely small black holes, formed by possibly electrically neutral and non-spinning compressed objects, effectively evaporate extremely quickly for reasons described by Stephen Hawking described decades ago. Such an object might be spin neutral and electrically neutral, but would evaporate too quickly to be observed well at galactic distances. It's difficult to imagine there is any circumstance in which a larger black hole would have no spin whatsoever, and a spinning black hole is _not_ spherical. The earliest models of black holes described spinning black holes, including the work by Kerr, Penrose, and Hawking. (http://arxiv.org/abs/1306.1019)

It would be understandable to leave out such details in a shorter essay that didn't make such absolute claims. But no competent science editor would have ever let this be printed in any science magazine above the 1st grade level: the proliferation of bad chemistry, physics, and biology of such badly written content is a disheartening effect of modern web publishing.

QA also doesn't get to test a lot of complete systems. It's very expensive, and for testing entire rocket systems including the third stage, it's pretty destructive.

> BTW, you call chemistry "basic"? Why is chemistry of any practical use to anyone but anyone but a chemist?

Do you cook, or take any medications? A bit of knowledge of how they actually work can be invaluable, and the handling of precise quantities with expected results is also valuable. So is the discovery of margins of error: chemistry in a simulator program doesn't provide that.

Complex systems, such as human bodies, often have a "bathtub curve" of failure probabilities. Numerous potential flaws are most likely at the start of the system's existence, which is why infant mortality and miscarriage remain noticeable even with the most advanced medical support. And as bodies age, more and more smaller flaws accumulate to cause more and more profound system problems. These range from vascular problems, likely to cause strokes and aneurysms, to the wear and tear on joints causing motion problems, to accumulated heavy metal poisoning and debris in the lungs, to the ongoing risk of cancers.

Until complete prevention or cures exist for all of those issues, it seems nonsensical to discuss the population issues of eternal life. Population _growth_ from people living even a decade longer is a much more real and noticeable issue in our economy and resources. So is the cost of medical care for those older people. We're already seeing problems with Medicare funding and elderly care being real economic and political problems in the USA. This is partly because, as we reach the far end of that "bathtub" curve for human beings, addressing one factor that might have killed people far earlier, such as very successful heart surgery and antibiotics for infections that used to kill older people easily, end when more complex and difficult problems finally occur.

I am, myself, old enough to feel these effects. They do accumulate.

Except that according to general relativity, gravitational _waves_ also are limited to C. As long as people confuse the current state of the system and what are basically "phase velocity" of changes in that state with the limitations of the "group veolocity", which is limited to C, we'll continue to see this sort of confusion.

> The problem is that sending people to Mars is very expensive and the billions of dollars wasted on sending people to die on an inhospitable planet could be better used for other things.

Which is what people in my youth said about the Moon landing and, frankly, has been a constant refrain against all space flight. It's difficult to know which parts of interplanetary flight and technology will pay off the most, and I'd prefer myself to pursue some of those likely byproducts first. But just a few potential benefits include the multiplication of our space capacity, enough to support zero-gee crystal and semiconductor manufacture, zero-gee electrophoresis that multiplies the sensitivity of certain types of chemical analysis, solar power from space based solar mirrors, and the migration of the most dangerous biological and nuclear research to orbital or lunar bases instead of Earth based bases.

Mars 1 seems a poorly selected political target for space development, because the obstacles are so very large they may absorb all the resources that could more quickly and effectively build a real space infrastructure. But watch, in the mantime, while many proponents of real space flight and technology manage to squeeze some funding out of the overall Mars 1 project.

> If the network infra-structure allows for POS to connect to the Internet at large

If it can't reach "the Internet at large", then it has to use modems and modem based access for credit card and debit card transactions. This is relatively slow, fragile, and expensive per transaction. Such devices are almost completely gone. Sadly, Windows XP is still commonly used on point-of-sale terminals. A typical vendor, like the one below, has _no_ Windows * based systems and supports only Windows XP and Windows 7.

                http://www.barcodesinc.com/p/

> This is what happens when you have employees who think they have a god given right to surf the internet

Or when you have an employer mandate to check employee email about store policies, schedules, delivery dates, and inventory, verifying store hours for other branches, verifying alternative vendor prices for price matching, checking the weather for a customer buying exterior paint, looking up a product review or product specifications with a customer, or any of a dozen other uses. It is _embarrassing_ for a modern vendor to be unable to work with a customer checking the same information that the customer can obtain at home on their home computer, or to be unable to print out the specifications for a product that the vendor sells.

Such terminals have become quite common and are much more necessary now that customers expect one store to be able to verify inventory or reserve an item before proceeding to another physical store. If they cannot do this, they will lose the sale to an online vendor.

This especially includes video monitoring. The UK has a television tax, called the "television license fee". It's still a tax, and it's used to help fund the BBC and other government sponsored media. This tax is being skipped more and more with modern computers downloading video directly, and the DRM on British television is being evaded more and more and the broadcasts being retransmitted live, around the world. The problems of collecting the tax are compunded by home entertainment systems no longer being CRT based and easily detected by the scanning vans.

        http://www.theguardian.com/not...

> I agree on this point. But since the proposal is for a generic design to deal with any incoming impactor, be it comet, asteroid, or even generation ship, then a design that can handle any impactor without modification is needed. There won't be time to design a modification if it is actually needed.

And this is where I would say _what!!???_ at lest if we were in person. "Any incoming impactor" includes objects of such potentially high kinetic energy, and of such unlikeliness, that we cannot even include it in any practical discussion. That includes, for example, intrastellar planetary bodies, "rogue planets". And that is where such a discussion would need need to assess, right from the start, trade-offs of likelihood of combinations of mass, velocity, and lead time to deal with it.

This was played out in the Rosetta Comet mission, which did _not_ succeed in embedding anchors in the cometary surface. Expecting a single design to handle both intra-solar-system objects, such as those from the Astroid Belt and of much smaller relative velocity to the Earth, and a cometary body that could be expected to be far, far colder and of a much larger relative velocity.

So right there, in the necessary requirements, are two profoundly distinct missions that might require two very distinct designs. Let's not limit such a discussion from the start in a single idea or technology that _must_ handle both.

It's hard work, and the pay tends to be far below the amount of work expected. Pre-school is exhausting, and grade school and high school often demand as many hours of support work, meetings, after-hours activities, and lesson preparation as hours of actual classroom teaching Many of those teachers also hung on through several deep recessions, and have reached retirement age or worked well past retirement age. And many "district" educational boards are encouraging senior teachers to retire early, so that younger, teachers with no seniority and lower hourly wages can fill those roles. Older teachers often disagree with the latest fads, and have the experience and knowledge to resist fads: middle management often finds those older teachers to be a dangerous "note of discord", and work politically to eliminate them quietly.

Please note that most of those issues occur in senior engineering roles. In IT, the sudden egress of senior tends to be much faster, and more concentrated to single companies.

Please actually look at the older generation, and revisit your own. Many younger people have _no idea_ how the technology works, much like their older peers. They have considerable hands-on familiarity with newer tools and no older habits to unlearn, but wait that same 10 years and they will be in a similar situation. I'm old enough to remember when 'C' and 'BASIC' were new and exciting. And it's a delight with my older colleagues and peers to learn new tools, and a personal delight to walk the young programmers through the same problems we had decades ago, problems they didn't realize the new tools would also have or which they ignored in testing.

Measure. It.

I spent a very, very long week with developers and network architects arguing about the subtle disrepencies of their layouts and software and how their software works. And eventually, I took actual measurements and showed that for far less money, using the simplest tools provided the faster solution at a tiny fraction of the complexity and cost when you _actually measured things_.

This has been a consistent lesson throughout my career. People theorize and postulate endlessly with complex analysys and essentially fraudulent testcases, and don't examine it in the real world.

Just. Measure. It.

Philae did not have to apply significant force to the comet itself, especially applying consistent force as the comet itself melts, and to consistently apply force to the same side of the comet. Even if a solar sail is applied purely as a solar powered brake, the tumbling of a comet or asteroid will require that the attachment points be able to _spin_, and not to tangle the shrouds of the solar sail on the tumbling object itself. If the spin of the object has an axis on the side away from the Sun, it should be possible to attach there.

There are profound issues of how to attach robustly and avoid fracturing a comet, leaving a potentially deadly remainder still on target for Earth, if it is a porous, frozen object. I'd anticipate significatnt sublimation and thawing on even the backside if the solar sail does not reflect _away_ from the object. But the idea provides far more available thrust and control than draping coverings directly on a tumbling asteroid or comet.

I'm afraid "log jam" typically means getting a penis stuck during anal sex. Feces do not "compact" from anal sex: unless you've already got other problems. they're not that solid, and intestinal walls are somewhat elastic. They _squish_.