g is also a unit of acceleration: http://en.wikipedia.org/wiki/G...
I prefer to say that g is gravitational field strength in N/kg. It is equal to the acceleration of a free falling object, but I think it is clearer to think of it as the number of newtons of gravitational force one gets per kg in the field. Of course, 1N/kg is the same as 1m/s^2.
There are two approaches to radiation tolerant computing. One is to make the processors hardened to radiation. These processors are usually slower, and use an architecture with fewer knowledgable computer programmers. This seems to be the approach on Orion.
In contrast, the Space X Dragon Capsule uses multiple processors operating simultaneously to create a fault tolerant system. To quote:
Dragon uses a "radiation-tolerant" design in the electronic hardware and software that make up its flight computers. The system uses three pairs of computers, each constantly checking on the others, to instantiate a fault-tolerant design. In the event of a radiation upset or soft error, one of the computer pairs will perform a soft reboot.[45] Including the six computers that make up the main flight computers, Dragon employs a total of 18 triple-processor computers.[45]
An advantage of this is that the processors are far faster. There are also many more trained programmers available for these more current architectures. Such systems arguably have similar (or better?) radiation tolerance to the older hardened processors.
It is an edge bet against a future where petrofuels are too expensive. With declining oil prices electric cars and hydrogen cars are going to start becoming less attractive just like what happened in the 90s last time this was attempted. Tesla might still sell with their angle on performance. These guys will probably not sell well at all. Plus cost effective ways to produce hydrogen without using petrofuels or natural gas have never actually materialized. One way is high temperature nuclear power plants using thermoelectric water separation but given the current investment into nuclear technologies it is not going to happen. Another way was concentrated solar thermoelectric but that is not cost effective with current methods.
Read my post. Hydrogen as energy transmission is a dead end physics wise. Use the electrical grid and get 90%+ effiency, or use hydrogen and lose most of your energy. Electrolyzing water is, and always will be very inefficient. It will not, cannot reach the efficiency of the grid.
If one were to buy one of these, how would one proceed to fill up? Would it be a viable transportation option for a road trip?
This is why I think electric vehicles have an advantage...you can put the charging station at your residence. All it needs is a wire. The infrastructure is already there, and can be expanded with relatively little expense. I can imagine charging stations everywhere one parks one's car. We all park our cars at some point, so we will all be able to charge our battery cars enough to make them usable, especially if the charging stations are high capacity.
In addition I think that in terms of space and expense, the potential power output of batteries is far larger than for fuel cells. I picture fuel cells as being finicky and complicated. If I am wrong, please correct me. However I have trouble imagining 800hp output (like the latest Tesla) from a fuel cell. My suspicion is that such a powerful fuel cell would be a Rube Goldberg machine.
Finally, and I think this is the real nail in the coffin for hydrogen as an energy source, is energy efficiency. Creating hydrogen from water, or from whatever other source you have takes a fairly large amount of energy. Let's say we take our hydrogen from water. How much of that input energy will actually make it to the fuel in terms of chemical potential energy? Some of the energy will be put into the O2 bond, which will not be transferred as fuel. Some (most) of the energy will be lost as thermal energy. Only a relatively small amount of the input energy will make it into the fuel. I would be surprised if it was even 20%, and I suspect it is less.
Compare this with gas turbine generators, that can have efficiencies well over 50%. So, you use your natural gas to generate electricity, in which you lose half of your energy already. Now you have a choice: you can use that electrical energy to electrolize water and lose 80% or more of that remaining energy. Or you can use the electrical grid to transfer the electricity directly to the car and lose only about 5% of the energy to the electrical grid.
The laws of thermodynamics are against the use of hydrogen is a fuel. Unless we can find a way of electrolyzing water that has an efficiency equivalent to the electrical grid (more than 90% - and such a process would violate the laws of thermodynamics), hydrogen as a fuel is an obvious dead end. If only the people who ran these companies knew a little bit of physics. I'll take a BSc in Physics any day over an MBA.
Here is a twitter discussion with Musk and Carmak that gives some reasons for using the fins. To quote:
Elon Musk @elonmusk Nov 22
Testing operation of hypersonic grid fins (x-wing config) going on next flight pic.twitter.com/O1tMSIXxsT
Elon Musk @elonmusk Nov 22
Grid fins are stowed on ascent and then deploy on reentry for "x-wing" style control. Each fin moves independently for pitch/yaw/roll.
John Carmack @ID_AA_Carmack Nov 22
@elonmusk Good luck. We had supersonic control inversion issues with actuated fins, went back to little thrusters that worked at all speeds.
Elon MuskVerified account @elonmusk
@ID_AA_Carmack No choice. Entry velocity too high for a precision landing with N2 thrusters alone. Must have aero surfaces for pitch trim.
My suspicion is that there will be a degree of unpredictability for this flight as they refine the control characteristics of these fins. Thus Musk was quoted as saying that the success probability was 50/50 for this landing.
This is a quote from Elon Musk on what he thinks about "process":
"I don't believe in process. In fact, when I interview a potential employee and he or she says that 'it's all about the process,' I see that as a bad sign.
"The problem is that at a lot of big companies, process becomes a substitute for thinking. You're encouraged to behave like a little gear in a complex machine. Frankly, it allows you to keep people who aren't that smart, who aren't that creative."
This just about nails it for me.
I forgot to mention...what I describe above is called learning by induction. Which is a form of probabilistic learning.
Our brains are based upon probabilistic computing? Not doubting it since I don't know enough of the "real" neuron details. Just noting it as ironic given how bad we are at assessing risk.
Perhaps I am not using the correct terminology. And I am not an expert...this isn't really my field. But I have seen neural network simulations which, for example recognize handwriting. You show the program many variations on the letter F, and the computer then learns to take symbols that look like the letter F and put them into that group. One can imagine that the brain is made up of many such processes. It certainly sounds like the way that I learned. See a spoon, see mommy using it to feed me, see mommy using it to feed herself. They are all different spoons, but they look similar and they seem to be used to move food from a bowl to a mouth. In a way it isn't that different than taking similar shapes and calling them a particular hand-written letter. It's just that we do this categorization at a myriad of levels on a myriad of objects and eventually of ideas themselves.
I suppose what I think might happen is that instead of building simulations of neural networks, that we will build actual neural networks using some form of electronic system. I don't know what that will look like exactly, but I suspect it is quite possible. After all, nature has already done it.
What is the point of having a nuclear power station for 5 billion dollars emulating a brain if you can make one for something like 200k by inseminating a real WIFE ? And then schooling the offspring etc.
If we can make a human level brain, then we can make something much smarter as well.
For starters, look up how many neurons you can simulate with a single CPU. Then, calculate how many fibers you need for the comms bandwidth.
There is the problem...I think that CPU's are the wrong tool. The problem needs to be re-framed. Perhaps we need synthetic neurons. Then we will need precisely one synthetic neuron to simulate a real one. I know...easier said than done. But we do know the basics of neuron function. Why can't we make a single electronic element that does something very similar?
Neurons can typically fire at a rate of 250Hz. There are about 100 billion neurons in a typical human brain. These neurons are networked in an extremely complicated and changeable parallel network. This network of neurons can be powered for reasonably long time with the energy contained in a bowl of oatmeal. Surely we will at some point be able to create a similar device, and one that doesn't require most of the world's computing power to run.
I suspect the breakthrough will come with a new computing paradigm, one that is based on massive parallelism. Perhaps it will consist of a silicon based device that mimics the network and function of neurons. I suspect it will be based on probabilistic computing, similar to how our own brains work. It will be taught rather than programmed. Perhaps there will be more states than merely 0 and 1.
I think that this is coming, because our brains are already doing it. And with incredible efficiency. Once we saw birds fly, and so we tried to do it ourselves. Eventually we figured it out. I think it will be the same with AI. We will copy nature, learn its principles, and then we will create our own version. And in doing so, I suspect our ideas of what intelligence is will fundamentally change.
There is a BBC documentary film maker named Adam Curtis who makes some fascinating and disturbing videos about society and control. He has access to the BBC film archives, and uses historical footage extensively. The assertions made are extensively documented and the interviews of powerful people are extremely interesting. I think that this video, The Engineering of Consent, is relevant to this discussion. It is one hour, and quite "stream of consciousness", but worth watching. It is the second episode in a series called The Century of the Self.
From the wikipedia summary:
"This series is about how those in power have used Freud's theories to try and control the dangerous crowd in an age of mass democracy." —Adam Curtis' introduction to the first episode.
Sigmund Freud, the founder of psychoanalysis, changed the perception of the human mind and its workings. The series describes the propaganda that Western governments and corporations have utilized stemming from Freud's theories.
Freud himself and his nephew Edward Bernays, who was the first to use psychological techniques in public relations, are discussed. Freud's daughter Anna Freud, a pioneer of child psychology, is mentioned in the second part, as is one of the main opponents of Freud's theories, Wilhelm Reich, in the third part.
Along these general themes, The Century of the Self asks deeper questions about the roots and methods of modern consumerism, representative democracy, commodification and its implications. It also questions the modern way we see ourselves, the attitudes to fashion and superficiality.
The business and political world uses psychological techniques to read, create and fulfill the desires of the public, to make their products or speeches as pleasing as possible to consumers and citizens. Curtis raises the question of the intentions and roots of this fact. Where once the political process was about engaging people's rational, conscious minds, as well as facilitating their needs as a society, the documentary shows how by employing the tactics of psychoanalysis, politicians appeal to irrational, primitive impulses that have little apparent bearing on issues outside of the narrow self-interest of a consumer population.
A scanner the size of an iPhone that you could hold up to a person’s chest and see a vivid, moving, 3-D image of what’s inside is being developed by entrepreneur Jonathan Rothberg.
Rothberg says he has raised $100 million to create a medical imaging device that’s nearly “as cheap as a stethoscope” and will “make doctors 100 times as effective.” The technology, which according to patent documents relies on a new kind of ultrasound chip, could eventually lead to new ways to destroy cancer cells with heat, or deliver information to brain cells.
Understanding is always the understanding of a smaller problem in relation to a bigger problem. -- P.D. Ouspensky
