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Einstein believed that an aether was necessary for his entire theory of General Relativity to have any validity at all.
Have you read Stephen Wolfram's A New Kind of Science?
He's trying to develop a completely fresh approach to physics based on cellular automata (and similar structures).
One of his models is a network of interconnected nodes which grows with time (representing the expansion of the universe). He puts forward the idea that the curvature of spacetime that you get in GR could just be an artefact of the density of nodes.
I'm not totally convinced that he can get the model to work out as easily as he wants, but it's certainly a compelling way of looking at spacetime. It also provides - effectively - an 'aether', without having all the normal problems of how compressible it is etc. It's just the network of nodes, and particles are just configurations of those nodes; so in a way, the particles and the aether are the same 'stuff'.
As I say, I'm not convinced, but it's an interesting direction.
I think clark's comments have been grossly misinterpreted. I agree with him. But he's quite capable of defending himself, if he sees fit.
Anyway...
The whole adult/child question hinges on what you define an adult to be. If we think that an adult is someone who understands the consequences of his own actions, then do we have to make everyone undergo an enquiry every year to test whether we think they're ready to be an adult? By this criteria, you could easily end up with 40 year olds who are legally children, and 10 year olds who are legally adults.
Instead, we come to some sort of collective judgement about an appropriate age at which we expect someone to be an adult. Maybe a specific individual is ready sooner, maybe not 'til later. But whatever, he knows in advance that this date is coming, so he'd better get ready for it.
The specific age we choose is arbitrary, but it's a 'bounded' arbitraryness. 5 is clearly too young, 35 is clearly too old. Different societies and cultures at various times have used different definitions for this age. It's far from a perfect system; it's grossly unfair to both early and late maturers. But it beats the crap out of any other system I can think of which leaves the judgement of an individual's adulthood in the hands of 'authorities'.
(Closed space example) Two spaceships ditto, but on an open-ended cylinder representing space with the cylindrical axis as the time-axis--one along a straight line on the surface and the other along a line spiraling around the cylindrical surface. The clocks don't match on arrival, with the spiral-line clock having run slower than the straight-line clock. But, by imagining the cylinder cut and unrolled, the spiral is seen to be straight as well, only longer. Velocity alone can be attributed to the discrepancy.
By 'unrolling' the cylinder, you change the geometry of the space. So the observation that the line is straight when the cylinder is unrolled doesn't have any bearing on the rolled-up case.
A line spiralling around the cylinder is travelling along a curved geodesic, therefore it is experiencing 'acceleration'.
(It's not acceleration in the dv/dt sense, but it is equivalent as far as the geometry of the space is concerned.)
But who knows, maybe it's just better if we just let the whole medical system crash and burn world-wide and just take it from there.... ???
You been reading Ayn Rand lately? :laugh:
why on Earth would ordinary workers want to risk their benefits, minimum wage, education, etc. by electing a right winger?
Arnold -- for lack of a better governor -- is good.
Arnold is right.
Arnold works.
Arnold cuts through, clarifies, and captures the essence of the evolutionary spirit.
Arnold in all of his forms -- Terminator, Commando, Running Man -- has marked the upward surge of mankind, and Arnold -- you mark my words -- will not only save California, but that other malfunctioning corporation: the U.S.A.
I was wondering how long it would take before you spotted this little discussion and chimed in!
You know, it's always a little scary when someone on a forum says something like this!
I haven't replied before now 'cos a whole batch of Preacher comics arrived from Amazon and, well, some books just need readin'.
(Oh, I managed to sneak into a politics thread somewhere and dump a sarcy comment into the broth. Doesn't count as real interaction; was just letting off steam between books.)
have you had much contact with the "Rethinking Relativity" stuff SpiderMan has made reference to in this thread?
I've read the article, and I have heard of the guy before. It's an interesting controversy.
My take on the whole thing is this:
As far as I know, General Relativity is fine as it is. It's based on a sound principle (that gravity and acceleration are, deep down, the same kinda thing). That gives the whole equivalence between gravitational and inertial mass a "logical basis" (for want of a better phrase). Otherwise it'd be hard to see why they should be the same.
On the other hand, there really is no fundamental reason why GR must be right. There are interesting cracks beginning to appear in the theory. The fact that it even allows the possibility of reverse time-travel gives cause for concern; yes, it may be that no time machine can actually be used (because noise and positive feedback will shut it down as soon as you switch it on). But still, the fact that such solutions of the equations exist is "odd", to say the least.
And it's proving desperately hard to kludge it into a good theory with Quantum Mechanics. QM is pretty much the best scientific theory ever produced. It just works so damn well, everywhere you try it. Yet we need two theories to describe the universe, not just one. How strange!
So I don't think anyone is unprepared for the fact that one or more theories are going to have to at least give a little at some point. Historically, that's always turned out to be the point at which the most fascinating revolution is about to happen; you've almost got it all worked out, but you just need to clear up these pesky details...
As to the "ether" theory...
Well, I can't answer that. Special Relativity works; it gives the right answers. Some people say that it's 'absurd' to imagine that electromagnetic waves can propagate without having a medium to "do the waving". I really can't go that far. How can we tell what is absurd for the universe at the fundamental level? What reason do we have to think that deep down it must behave in a way that is analogous to the things we see at our macro level?
When you push a stone with a stick, you get a kind of image in your mind of what is going on. But when you analyse what is actually happening, it starts to get difficult to say what is really going on at the tiniest level between the stick and the stone. The atoms are hitting each other. Well, not really the atoms, the outer electron shells. Well, they're not really pushing each other, more sort-of excluding other electrons by a combination of quantum effects and electric repulsion. And that's mediated by virtual photons being exchanged. And these photons aren't literally pushing the electrons (for otherwise how would electric attraction work?).
It's so tempting to try to find something deep down which works just like an everyday thing we're familiar with. Like throwing a ball, or pushing with a stick... or a wave on water. But truthfully, it just ain't like that. We don't have the faintest idea what this stuff really is, or what makes it do it. Every so often we get another theory which explains how things work in terms of something at a more fundamental level. This just pushes the same mystery down further, but it's still there. It's beginning to look like we may be reaching the end of these detailed explanations, at least as far as particles are concerned. Or maybe not; watch string theory for exciting developments.
So while we can't analogise fundamental physics to everyday life, we can do the next best thing: we can describe it in exacting detail, using the most phenomenal language ever developed by mankind: mathematics.
Now, math doesn't even attempt to tell you what a thing is, or what it means. It just tells you what it does, or describes its attributes.
Why the universe appears to follow mathematical laws, I have no idea. But I'm convinced that somewhere in it all, something that makes the universe run resembles in some way whatever it is that the math is describing.
Which isn't to say that the universe is mathematical; I once heard a lovely quote to describe this position:
"Just because the Bible can be written in English, it doesn't mean God is an Englishman."
Yup, that's right.
So this is basically my long-winded way of saying that I don't know, and furthermore, I'm not sure we can ever really know, and we have no way of telling what is 'absurd' (unless it generates a bona-fide logical-implosion-type contradiction with reality).
But it's sure as hell fun getting more and more details, learning bit by bit how all the pieces fit together, how we can manipulate them to make them do what we want.
Should I be worried about such questions .. or should I get out once in a while, have a few beers and loosen up?!!
Beer good. Get yourself a copy of A Man, A Can, A Plan. Some great beer recipes in there.
Anybody care to offer an outside assessment of who should lead my state?
How about a system of governance based on rational, logical scientific principles?
But for a taste of one of the doubts about particle physics that percolates through the recesses of my mind, try this logical sequence:-
1) What's a photon?
A vibrating electromagnetic field.
2) What's a field?
A region in which a force (in this case electromagnetism)
exerts its influence.
3) How is this influence exerted?
By the exchange of particles called carrier bosons.
4) What's the carrier boson for the electromagnetic force
called?
A ... photon .. !!!HUH???!!
I think step 2 is causing the problem.
"What's a field?" "A region in which a force exerts its influence."
Yes, but that's not the pertinent attribute of a field to this argument. A field is an array of potentials, in this case electric and magnetic.
The self-sustaining wave known as a photon depends on the electric and magnetic components continually generating each other. AFAIK, there's nothing to suggest that this 'internal' physics of the photon has to be mediated by another photon. It's just a wave in the field, not the potential at one part of the field being transmitted remotely to another part via a photon.
Of course, it might be that virtual photons are required to make this work, but I'm just pointing out that it doesn't have to be that way, so there's not necessarily a contradiction (or endless regression).
[Even if there is an infinite regression, that's not necessarily a problem. If each photon requires 'smaller' photons to sustain it (and I'm deliberately not defining 'smaller'), then you've got an infinite sum; but as 'every schoolboy knows', an infinite sum can result in a finite value. (And I've deliberately not defined what I'm summing.)]
Crazy li'l ol' universe, huh?
Einstein is very clear, if you read Relativity, his book on the subject, that it is not velocity, but acceleration which causes time dilation. You can go as fast as you want, but if it's at a constant velocity, you won't experience time dilation anymore than you will experience artificial gravity (G-forces).
Both velocity and gravity cause time dilation. The one caused by velocity (or strictly relative velocity) emerges in Special Relativity. The dilation caused by gravity is shown in General Relativity.
Where acceleration comes in is the resolution of the twin-paradox. If Bill leaves Earth in a space ship travelling at 0.99c, while his twin brother Fred stays at home, then each of them will perceive the other's clock to be running slower than his own. (Note that this has nothing to do with the propagation delay due to the finite speed of light. Even if you take that into account, the time dilation is there.)
This looks like a paradox - how can each clock be running slower than the other? - but it's fine provided each of them continues in their current state, Bill travelling at a constant velocity and Fred sitting at home.
The interesting thing happens when Bill turns round and heads back to Earth. When he arrives back home, Fred has aged more than Bill i.e. Fred's clock has been objectively running faster than Bill's.
This is resolved by the fact that there is an asymmetry between the brothers. Bill has undergone an acceleration (when he turned his ship round) while Fred has not. This asymmetry accounts for the difference in the clocks.
[Pedants may note that there is a slight inaccuracy in my example. Bill has accelerated from Earth at the beginning of the trip, thus generating an immediate asymmetry between the brothers. Technically, we should have Bill on an infinitely long journey extending into the distant past and future, no acceleration and constant velocity, and 'flying by' Earth at 'zero-hour'. However, this complication doesn't significantly affect the thought experiment, so it's usually omitted from it.]
The gravitational time dilation is due to the difference in gravitational potential between two points. So a clock in orbit around the Earth runs slightly faster than one sitting on the surface. This isn't the same dilation as that caused by velocity differences.
[Pedant alert again... superficially it isn't the same case, but if you delve really deeply into relativity, they are sorta kinda the same kinda sorta thing deep down... but hey, let's not go there! ]
Basically what a "technocracy" is about is a system of governance based on rational, logical scientific principles.
The idea of a 'technocracy' scares the living bejeezus outa me.
Especially as I know exactly what rational logical scientific principles should be applied to society. I know for absolute certain that I am right...
... and I also know that I have believed this in the past and then realised I was utterly wrong.
As to the suggestion for universal participatory democracy (i.e. everyone votes on governmental decisions), from what I've read about places this has been tried, in practise the votes are dominated by those groups which have a strong dogma e.g. commies. They will be motivated to put the effort into each vote to achieve their ends, whereas the "comfortable neighbor" types, who subscribe to a wooly pragmatism, don't have the will or interest to devote time to researching each and every subject in the level of detail required to exercise their franchise.
Compelling people to vote doesn't solve the problem, as they are then voting either with superficial 'gut' feeling or randomly.
*Has anyone read _Snow Crash_ by Neal Stephenson? It's available at Amazon.com.
Not read that one, but I have read one of his other books Cryptonomicon, which was very entertaining indeed.
From what I've heard, Snow Crash is better.
It's on my list of stuff-to-read-maybe-one-day, so when you've read it, let us know what you think.
...and of course we know they LOVE to put "u" in everything from "colour" to "neighbour", etc. :;):
Hey, what's with all the Brit bashing today? :;):
Oh, and my favorite (albeit old and outdated): "Gaol" and "gaoler". What's that? Jail and jailer.
Heh... I doubt that many Brits under 40 would even recognise the word 'gaol' any more. They'd probably think it meant "strong wind".
Another one that amuses me is that Americans refer to the "British billion", meaning a million million. But we haven't used that for ages. Since before I was born, a billion here has been a thousand million, just like in the USA.
We also get our word "faggot" from the Brits, but it originally had a VERY different meaning than what we moderns ascribe to it:
And "faggots" here are a kind of meatball. I recall once eating lunch in a pub, and the girl was bringing out the food for a nearby table. "Faggots?" she called out, and a table full of Americans looked utterly stunned! Maybe they thought she was identifying the customers by their sexual orientation. :laugh:
::EDIT:: Just now recalled that America's Founding Fathers, who of course were originally British citizens, substituted "s" for "f" when found in the middle of a word. For instance, if you look at a copy of the founding documents, you'll see the word "President" written as "Prefident." No kidding. It seems they used "s" as we use it -only- at the beginning and ending of words; for an "s" elsewhere in the word as we know it today, an "f" was used. It's quite a challenge to read the old English style, but is definitely worth the effort.
Ah, but it's not really an 'f' though. More of an elongated 's', a bit like the integral calculus symbol.
Anyway, I'll have a chance to observe some American nuances when I am back in the USA next week. Woo-Hoo!!!
I would kill for a chance to sleep in free fall just to see what it's like. I imagine it would be a pretty restful sleep..unless your arm starts drifting around and bops you in the head!...
I hear astronants have a hard time getting more than six hours a night in the Shuttle or ISS, although their bodies still require the same amount of sleep they're used to on Earth.
From what I've read, the effect of zero-g on the human body is very much like having a head cold (because of all the fluids 'collecting' in the upper body). Probably feels a bit like lying down with your head slightly lower than your feet.
I'd imagine that this might have something to do with the lack of sleep.
Re. Sleeping positions; Where in the World do you all get those names for the positions you sleep in...?
From the BBC article linked above. (We didn't just make up all this nonsense ourselves! :;): )
My preference would have to be the "Weightless" position, next to a viewport facing Earth. in the ISS!
WHAT??? Heretic! Don't ya know this is a Mars Society board?
Ooh, what a strange thing to think about!
I think I do all of them in one night, except for Starfish, which doesn't look good for sleeping (though it seems ideal for - ah-hem - other purposes... and now I've started on this track, I'm definitely not gonna discuss Freefaller ).
Can antimatter bombs be exploded behind a ship much like the proposed orion a bomb starship? The force coming from the energy behind the ship could in theory propell it to incredibly fast speeds, speeds that would be faster if nuclear fusion or fission was used to make a whole lot of kinetic energy. Could someone design such a ship that would make a whole lot of energy come out of the back of the ship or be exploded against the side of the back of the ship in order for it to accelerate to an extremely fast speed?
No theoretical reason why not. But the engineering would be pretty nasty, principally because antimatter is such a damn dangerous thing to handle. You need some really clever storage tanks to ensure it doesn't touch any normal matter. I think at present most people are considering some form of electromagnetic container; the worry with that is that the ship goes to hell in a radiation basket if the power fails for even a tiny fraction of a second.
Having said that, some bright spark will probably come up with an idea for storage that is fiendishly simple, and will leave everyone 200 years hence scratching their heads wondering "How on earth did the early 21st century folk not think of that?"
The other big problem is generation of antimatter. At present, it's still hideously expensive to produce (in energy and cost terms).
Something for the Phobos Research Company to investigate maybe.
Another good option is IrfanView. Very easy to use, and best of all... it's FREEWARE!
*Hey Pat! Long time no see. And just the other day I was recalling (in preparation for this anniversary date of 9/11) the exchanges you, Phobos, Shaun, and myself (and perhaps a few other folks) had regarding your having been in New York the day prior to 9/11/01. I hope I'm recalling that correctly.
Hey Cindy, how ya doing?
Yeah, been a bit too busy for a while to post. I've been browsing now and then whenever I could grab a moment.
You remember correctly, I was indeed in New York (and the WTC) the day before 9/11. That awful day is always in my thoughts, but you know, NYC is still a beautiful city. Crazy and smelly, sure, but beautiful nonetheless.
If, for example, you caused someones death from unsanitary food preparation you should be punished.
Fat lot of good that does me, the person who ate the hamburger. I'm dead now.
clark, some of your arguments are good, some are not so good (IMHO).
However, this one is just a bit unfair. You can make that argument against absolutely any system whatsoever.
No matter what protections or regulations you put in place, you can't actually stop someone from committing, or at least attempting to commit a crime. The most you can hope to do is to try to catch them at it, or planning it, and make a believable promise to catch and punish them if they do manage it.
---
As a further aside (nothing to do with this post), someone said above that one of the tenets of libertarianism is "do not lie".
I ain't ever heard that one before, and in fact I don't think it's right. There are many times when it's absolutely right to lie, or at least not wrong to do so. What you can't do is lie about something you're offering in trade i.e. misrepresenting attributes of whatever it is you're selling. That's plain and simple fraud. But there's no problem with lying about (for example) your age, or the number of indoor lavatories in your house, in answer to a casual enquiry.
I don't really have any favorite 'types' of music. Just particular tracks (or bands that tend to produce good tracks).
And it also varies tremendously with mood.
Still, on the whole I prefer modern music to old stuff (pre-1990s). At the moment I enjoy songs by Avril Lavigne and Linkin Park, among many others.
I like a few more obscure groups, such as God Speed You Black Emperor.
And I also enjoy some old stuff, like Mozart's Requiem (this is my all-time favorite album, though a lot of Mozart's other stuff is bit sickly for my taste). Wagner's Tannha?ser is pretty stirring.
For background music while tidying or whatever, I listen to Country (Gruene with Envy on Live365 satisfies this nicely).
Do you think file sharing is wrong, or acceptable? Are there conditions?
I don't know.
The reason I don't know is because I haven't decided whether the the concept of intellectual property is truly legitimate or not.
I have read excellent arguments both ways. And I still can't make up my mind.
I normally take such indecision as a signal that I don't really understand the problem enough.
I'm reading the Honor Harrington novels by David Weber. Right now, I'm about halfway through Ashes of Victory.
Very enjoyable military sci-fi in the style of Horatio Hornblower.
I'm also reading:
Cheap Shots by Marc Animal MacYoung (my favorite personal defense author)
Saddam's Bombmaker by Khidir Hamza
the Penguin History of the World
Human Action by Ludwig von Mises (I'm proofreading the electronic version)
Hacking Exposed
Object Oriented Software Construction
Upgrading and Repairing PCs.
And I'm also squeezing in the Harry Potter novels which I didn't get time to read when they came out.
It seems to me that many of us are using the same words to refer to very different concepts and very different economic systems. Unless we all share a common understanding of what is meant by
capitalism;
socialism;
free markets;
communism;
anarchismetc, etc, etc,
there will be plenty of heat but no light.
Darn it, you're giving away the plan!
The capitalists have hooked up this forum to a turbine, and they're using the heat to generate lots of electricity which they're selling out of a van in downtown LA.
Hey, you gotta raise money for the Mars Mission somehow!
I dunno where you learned about capitalism, but your description bears no resemblance at all to the concept I associate with that term.
In capitalism, what you are supposed to be concerned with is bringing resources under your control. You are not supposed to be concerned with anyone else ; if you are, you'll go out of buisness.
The name 'capitalism' is given to a system in which property is privately owned ('ownership' meaning that you may use and dispose of your property as you see fit).
It says nothing at all about what you are 'supposed' to do. You may assume any ideals you want, anything from total ascetism to lusting after untold riches. All these are compatible with capitalism.
Be concerned with other people if you want. Don't give a crap if you don't want. That decision is one that you make independent of the existence of capitalism.
Now, normally, it is assumed that to be capitalistic there should be certain restraints on the profit motive: you should not, for example, be allowed to kill someone if they do not work for you.
Uhh... more to the point, you're not allowed to kill anyone, regardless of whether they work for you or not! (Self-defense excepted, of course.)
However, this constitutes a restraint on the profit motive.
No; in a capitalist system, you are allowed to use your property as you see fit. The corollary to this is that you are not allowed to use other people's property (including their bodies) unless you obtain their agreement. (This follows because if you were allowed to use their property against their will, then they would not be able to exercise their own property right.)
There's no restraint of anything involved here. Just a consistent application of the principle. Killing someone or stealing their property is inherently anti-capitalist.
Are we then to conclude that pure capitalism actually has regulation built in? Some would say this, and in a sense they are right--it depends on the language we use. But in a more consistent sense, "pure capitalism"--that is, a system where the profit motive drives all, is simply warlordism and utter tyranny. This is not difficult to see.
These 'restrictions' on certain actions (killing, theft) are not 'tacked-on' to capitalism. They're not regulations that must be added in order to rein in the 'capitalist excesses'.
They are part and parcel of the consistent application of property rights. You simply cannot simultaneously advocate the principle of private property and permit killing and theft. That would require the ability to sustain a contradiction, and the last time I checked, the universe still won't permit that.
As to the 'warlordism' and 'tyranny' claim, that's a bit outside the scope of a short analysis. In brief, I think that it's a lot easier for people in a capitalist system to stave off these threats than in any other system I've ever heard of.
6) Pre-orbital abort capabilities
In terms of 6, even if we had known the implications of the foam pre-exit from the atmosphere, the orbiter was doomed. at that point, our only abort option would have been to leave the atmosphere, orbit and come down. obviously, the shuttle would have found the same fate.
I was reading this on the NASA site a couple of days ago:
The idea is to use paraffin as a rocket fuel. This kind of technology would vastly increase the range of abort modes available; the current restriction is the fact that you can't turn off the damned SRBs. Once they're lit, you're going come hell or high water.