We have NASA ice cores that show more wild swings in our temperatures and more extremes than we see now.
Well, when we're at the extreme for a temperature swing, that's a little too late to act.
We're already off the charts for something else - carbon dioxide. We know that CO2 plays a huge role when it comes to temperature, life, and oh, a half dozen other things.
Why isn't it enough that CO2 is off the charts (and accelerating off the charts) for the current geologic epoch? We know it's anthropogenic. It's not sustainable to have the rate of CO2 emissions that we have. Why isn't that enough?
Millions of species would survive the entire time, and species diversity would be back where it is today in a geologic eyeblink.
Why is this mindset so prevalent? It's not like the Earth is sticking around forever - life isn't incapable of adjusting to all conditions. It needs water. Do something bad enough to the Earth's atmosphere such that liquid water no longer sticks around, and they all die.
Sufficient amount of radiation would do it, too, though that would require a fair bit more effort. Though silly stories love to make jokes about the resiliency of a cockroach, a sufficiently high dose of radiation really can kill anything. It's that whole "shatter all your DNA" thing.
Heck, if you started life back at the whole primordial ooze thing, it wouldn't have enough time to evolve again. Many models suggest that life has less than a billion years left, and it took life 3 billion years the first time.
Sure you can. The Earth's going to die on its own when solar forcing breaks the hydrologic cycle, but we could probably speed the process up by releasing really really huge quantities of CO2. Burn all the limestone on the planet (hell, we've burned a large fraction of the oil on the planet, so just need a way to power cars off of limestone), send the CO2 levels sky-high, destroy the ozone layer to speed up water disassociation, and the planet would be dead and gone.
(A better approach would be to use those bombs to change the orbit of a nice, large, 100km asteroid to intersect Earth's. And even then, you'd be pretty hard pressed killing everything.)
Actually, I think you could probably do it easier. We've already proven capable of increasing the CO2 in the Earth's atmosphere by about 20% or so - almost 100 ppm so far. Just need to repeat that about 20 times over, which would take effort, but is probably not impossible. An economic reason for burning limestone would help.:) Plus releasing an absolute ton of methane, etc. Add in the complete destruction of the ozone layer (CFCs are our friends) and you could probably strip the planet of water in a few hundred years.
Life's resilient, but water drives everything. Push the hydrologic cycle off the edge of a cliff, and it isn't coming back.
if they are unable to experience their own existence, then to them they don't exist...
But they are experiencing it. They're just not remembering it. Remembering things allows you to have control over your own experience, but it's not what provides the experience.
You could argue that my responses to people (as non-sensical as they were) were just programmed responses.
A person who experiences complete retrograde amnesia could claim the same thing when seeing film of himself before an incident. It's just lack of memory, not lack of being.
Not to bring up philosophy, of course, as they didn't exactly have the same context as we're describing, but Descartes was right when he said "I think; therefore, I am" - not, "I remember; therefore, I am."
Of course, it's also important to realize that determining "being" is completely impossible. I don't know that anyone else on the planet is conscious - I just presuppose that they are. I know I am, and I know that I still existed even while I was asleep, even though I don't remember it. But I have no way of proving that, of course. I could've been created out of the blue this morning, with the memories I have. So you have to reason "I am now; therefore it is logical that I am the me that was before, and I am the me that will be."
when this mechanism surely ceases functioning just as it would with injury, the experience of the dead person would be the same - nothingness.
I can't see how you can argue that. Your memory isn't who you are - it can be faked, manipulated, damaged, or destroyed. But the important thing about living isn't being able to remember. It's being able to choose. And given that we have no idea where that mechanism comes from, it's impossible to say what happens to it after death.
because with that small part of my brain not working I was literally no longer a person, I didn't exist as a mind - I was just some pile of animated meat.
Hate to comment on this, but if you were a person during that portion, how would you know? You couldn't remember it.
Weather fluxuates. Always has. Always will. To claim that every -previous- shift in climate was completely natural but THIS one is caused by humans...
Atmospheric composition fluctuates, too. Always has, and always will (a lot of it has to do with continental drift, for one). But claiming that every previous shift in CO2 levels is natural, but this one is anthropogenic... makes sense. The spike occurs within the period of anthropogenic CO2 emissions. The amount is consistent with levels of human CO2 production. If you look at ice core data, the last 150 years isn't just an anomaly. It's off the charts. By a lot. (And yes, CO2 levels have been higher in the past, but unless continents have been moving around half the planet while I wasn't looking, that probably isn't the problem).
So now we know we've got an anthropogenic CO2 spike. And now we're seeing a temperature spike. We've got a theory which connects CO2 to temperature which is really, really well founded (by many, many years of agriculture). Unless someone is proposing a theory which explains the temperature spike via other methods while simultaneously explaining why the CO2 spike doesn't cause it, and predicting something the other one doesn't, Occam's Razor says to choose the first one - it's simpler. One cause, two effects. Saying "it's natural fluctuations, that's simpler" isn't right because you're ignoring data - you have to explain why the CO2 rise isn't causing a temperature spike, while simultaneously a different process is.
It's simply bad science to claim that the climate change we're seeing isn't likely to be anthropogenic. Is it anthropogenic? I don't know. Could be that the Martians simply turned up their remote Earth thermostat. Got me. But until a better explanation comes along, this one's the most likely to be true.
Do we understand everything about climate? No. That doesn't mean that the intelligent course of action isn't prudence.
I don't know how I'm going to die, but that doesn't mean that I shouldn't exercise and eat healthy. I could still be hit by a car tomorrow, making all of my work pointless, but it was still the right action to take.
Mercury doesn't really have an atmosphere. Being small and close to the Sun will do that to you. You'll find papers on Mercury's 'atmosphere', but it's not stable. It'd be more properly called an exosphere.
We'd never, ever, ever be able to measure oxygen in Mercury's atmosphere from another solar system. No way.
My only point is that the existence of oxygen in the atmosphere is not a litmus test for life.
Significant oxygen. Oxygen doesn't stay very long in the atmosphere since it binds to, well, everything. It's trivial to measure the atmospheric content of a planet (spectroscopy rules). If you get a planet with say, an oxygen fraction of 10% or more, and temperatures anywhere near reasonable, it's got life.
Right now, if we were looking in on Earth from another solar system, Earth would look very strange - it's the only terrestrial planet with a significant oxygen component. That's the signature for life. Easy enough.
Yes, but bremsstrahlung losses prevent a useful He3-He3 reactor by a wide margin. Brem losses for D-He3 could kill it completely as well, but it's definitely gone for He3-He3.
The benefit of using helium 3 is that you bypass the radioactive element tritium.
The benefit of Helium-3 is that its fusion reaction is aneutronic. This means that the containing vessel wouldn't be irradiated, and it's more efficient - that is, it should be easier to generate ignition with Helium-3 than with a similar fuel that wouldn't be aneutronic.
The downside, of course, is that the reaction involved is D+He3, which means you'd have D+D, and He3-He3 side reactions, and D+D does give off neutrons. And D+He3 takes higher temperatures than D+T. So it's a little - um - daring for the Russians to be saying this, although it's not impossible to believe that given a supply of He3, there'd be economic incentive to build a freaking big fusion reactor.
Seriously though, I hate when people think like this. Maybe by looking out into deep space, we'll discover some new method for easily detecting life which we can then apply to Mars.
The other problem with that quote is that searching for life on Mars is difficult because Mars is very, very close to dead. Mars isn't teeming with surface life. That's pretty much a total given. It might have life clinging in a few underwater reservoirs, but it's not like Earth.
If someone was able to see Earth from a distant star, they'd be able to tell that there's life on the planet in a heartbeat. All you have to do is look for atmospheric oxygen.
We're not looking for marginal life. We're looking for another Earth.
I think this is quite a departure from what is conventional accepted about gravity. The gravitational constant, G, sets the scale for the force of interaction of gravity. It is normally assumed that this value is constant throughout the entire universe.
This isn't a new idea. This idea has been around a long time - it comes from Mach's principle (yes, that Mach) which essentially states that the inertial mass of an object only means anything in context of other objects. Taken with the equivalence principle, this means that gravity depends on the spatial distribution around it.
General relativity does not satisfy Mach's principle - you can create an "empty Universe" which solves Einstein's equations. There have been several modifications to GR to try to satisfy Mach's principle. The simplest one is Brans-Dicke theory, which does exactly what SVTG does - allows G to vary. Brans-Dicke theory is essentially identical to general relativity if the coupling between the scalar field and the tensor field (gravity) becomes infinitely weak. Sounds like SVTG is an extension of Brans-Dicke, allowing a scalar, vector, and tensor component for gravity.
I've always wondered why they don't teach what virtual particles are directly in most physics courses. It's very strange. Even when you get to quantum field theory, if you ask "what's a virtual particle?" the answer that you'll get isn't very illuminating - "it's a particle off mass shell." If you read the Wikipedia article on them, you'll see what I mean.
The difference between a virtual particle and a real particle is... well... very little. In any calculation, you usually have a "beginning" and an "end". Like, you say, "an electron scatters off of a photon". You don't know where the electron was, or what it was doing, before the scatter, or what it does after the scatter. We call that electron 'real'.
But you learn in QFT that electron-photon scattering is a two-step process: first, the electron absorbs the photon, the electron propagates a bit, and then the electron reradiates the photon in a new direction. ("bit" here is "really, really, really small"). There's a problem, though - while the electron is propagating, it "isn't really" an electron - that is, it's off mass shell. For a normal electron, its energy is just the quadratic sum of its mass and its momentum. For this "thing", it's not - its energy is a little bit higher than the quadratic sum of its mass and momentum. If you would treat the electron mass as a shell in "energy-momentum" space (where m = sqrt(E^2-p^2)), that "thing" has left that shell. But it still carries all the quantum numbers and interactions of an electron - so we call it a "virtual electron". In a sense, you can think of it as an unstable excitation of an electron, with the "decay time", if you will, being determined by the energy of the "absorbed" photon. High energy, short lifetime, and vice versa.
Now you can see - if the energy is really low, and the lifetime really long, is there any difference between a real and virtual electron? No, not really - it's just a mathematical artifact. If a "virtual electron" interacts with a "real electron", it means in order to calculate it correctly, you need to take into account the interaction that caused the first electron to go off-mass shell.
Taking those interactions into account is called "radiative corrections" - they're first order corrections to QFT, because quantum field theory is perturbative. It starts off by calculating the most important portion of the interaction, and then corrects things later.
So does it matter if a graviton is virtual or not? No, not really. All the exchanges being talked about here are all soft, so the gravitons are very, very close to real.
then why doesn't placing one object in front of another reduce the influence of the body that the second object is shielding against?
Because gravitons don't "push", they only "pull". The only reason we can shield against, say, an electron, is because the electric field can "push" as well as "pull".
Since a gravitational interaction is always purely attractive, any material you put in the middle, to first order, doesn't have any effect. If you've got particle A, B, and C, if A exchanges with C (A==C), and then you put B in the middle, forcing A to exchange with B, then B to exchange that same graviton with C (A==B==C), the net effect is the same - B gets momentum towards A, and C gets momentum towards A because B is now heading towards A.
If you read the article, though, SVTG says it does have an effect - in exactly the wrong way you'd expect. That is, putting matter between doesn't shield gravity, but makes it stronger. And that's how they can explain galaxy rotations - gravity is stronger near the dense central region, and weak farther away. That's also how they explain the Pioneer anomaly - it's not an acceleration as much as gravity gets weaker as density decreases (so the farther you get, the weaker it gets).
The "scalar" part of scalar-vector-tensor gravity makes me think it's related to a Brans-Dicke theory, which was an attempt to satisfy Mach's principle - that is, the mass of an object only makes sense if there's something else around it, so gravity itself should be dependent upon the matter distribution. This theory, also, seems to satisfy Mach's principle.
However, we're still left with the age old question: If gravity is manifest as a particle, why can't we shield against it?
You typically think about stopping "particles" with other particles - like a wall. That's a very classical idea. But in order for a particle to stop at a wall, it needs to interact with that wall - in fact, it needs to either be "absorbed" by the wall, or it needs to be totally deflected by the wall. But in either case, it needs to interact with the wall.
Neutrinos, for instance, don't interact with much, since they only interact via the weak interaction. So we really can't shield from neutrinos that well, although you could build weird gadolinium-doped materials which would probably cut down on the flux of neutrinos more than others. Thankfully, neutrinos interact just like normal matter when they *do* interact, and so you could conceivably shield against them - just not easily.
As for gravitons, though, the situation changes - now you have to ask "can we build a material that interacts with gravitons?" Well, yes - all matter does. But annoyingly, that material itself would produce gravitons as well, and in terms of the SVTG theory, it sounds like it "conducts" them through, too. It's a lot like magnetic shielding - putting a material that interacts with magnetic fields isn't enough to shield a field from you. You need a high-permeability material - that is, one that makes it easier for a magnetic field to flow around you rather than through you.
You can even realize this based on the spin that the graviton has: a graviton would be a spin-2 particle, and any interaction with a spin-2 particle as its mediator must be an attractive potential. Without the possibility of repelling a graviton, you can see that you can't build a shield.
Note that we don't have any fundamental spin-2 particles other than a graviton, so it's understandable that naive ideas don't work.
Are they invalid, or reserved ones? I hate it when shows use invalid ones (300.631.42.12 or something like that) when they could just as easily use a reserved IP address. It'd be easy enough to ask any geek "give me an IP address that sounds random, but won't actually be anything", and give them 172.18.101.84 or something similar. (does anyone use the 172.16-31.x.x block?)
Yet Einstein implied as much when he said: "God does not play dice." Many scientists and mathematicians are guided by what they see as divine beauty. If that isn't supernatural causation, what is?
That's not supernatural causation. That's human opinion.
What you're missing is that Einstein was eventually proven wrong. He had an opinion, he tried to justify it, and he failed. Bohr's response is appropriate: "Albert, who are you to tell God what to do?" Which is, curiously, an appropriate response to this entire argument - who are the ID people to tell God how he created the Earth, and humans?
The scientists and mathematicians don't throw out theories based on their "beauty". They throw them out based on evidence. Ugliness is not a kiss of death for a theory, it just makes goofy scientists with an idea of how the universe is supposed to work dedicate their life to trying to figure out how to get around it.
It should be pointed out that natural evolution is also a nondisprovable theory.
No, it's not. What the hell makes you think it is?
The process of evolution is a fact. First off, it's idiotically simple. We've got genes. We pass them to offspring. Those of us who live, pass off our genes to offspring. Therefore future generations look like those who lived. Go fig. Humans have been doing it for thousands of years. We call it dog breeding. Second off, it's observed. We see it. We know the process happens. Regardless of what that process has done, like "the greenhouse effect", no one is challenging that survival of the fittest exists - just what role it played in the development of species.
The theory of evolution - that is, the process by which an amoeba became E. coli became a worm became a fish became a frog became a reptile became a mammal - that's the theory. And that is challengeable - both genetically, anthropologically, and hell, directly! If we really wanted to - and I mean really wanted to - we could look for the reflection of light reflected off of the Earth from distant bodies, thus looking back in time on our own planet. That information is there. It is challengeable. It makes predictions which can be tested.
Intelligent design, however, is not challengeable because it doesn't describe a process. Just a creator. And anyone who's taken journalism class should know that knowing "who" did something doesn't tell you "how" it's done.
The nature of life, the structure of life, and the existance of life can only be explained as an engineering miracle that was created.
That's not an explanation.
In fact, let's get completely specific. There's a decent amount of evidence to suggest that the planet was, in fact, created, and wasn't here at some previous time, right?
So how do you get from that ball of "stuff" (let's call it dust) to the world we have now?
Exactly how?
Saying it "just happened" isn't an explanation. Saying it "was a miracle" isn't an explanation (that answers "why" or "who", not "how").
What you actually want to say is that there is no complete explanation for how life formed. None. Nada. Zero. Zilch. Saying "it was an engineering miracle that was created" isn't an explanation. If ten million years from now, someone finds a clock lying around, and they want to explain how it was made, even if they (rightly) conclude that someone built it, that doesn't answer how it was built. Just who built it.
Likewise, knowing how something was built doesn't necessarily tell you who built it.
Stop trying to offer up "miracle!" as an explanation for "how". It's not one.
Just because you wrote more stuff it doesn't give you the leeway to screw up more...
Uh, so if the Brittanica has an article which says "Bill Clinton was the 41st President of the United States" and that's all, and Wikipedia has a 12-page entry on Clinton which gets his date-of-birth wrong by one day but is perfectly accurate everywhere else, that's okay?
Look at some of the articles listed. The Wiki article (on Robert Burns Woodward) has a detailed breakdown of his life, his career, discoveries, and Nobel prize. The Wiki article's section on his honors and awards - which is just a list - is longer than the entire Britannica article!
Curiously, though, reverse engineering is. So apparently, you're allowed to circumvent the protection and extract the ISO if you claim you're working on reverse engineering the XBOX 360.
So when Microsoft comes yelling at you, apparently you can yell "dude, it's okay. I'm a hacker."
Did you happen to hear the multiple times that they call humans "Sons of Adam and Daughters of Eve" ?
That's just terminology. It doesn't make it an allegory of Christ. I could stick those terms into any random fantasy setting, and it wouldn't mean anything there, either - other than someone wanted to use a phrase that sounded more regal than "men" and "women".
Perhaps you missed the part saying that Aslan died for what essentially are the sins of another.
There's the kicker. Then again, the original poster is correct that it's not a simple allegory for Christ. It's a retelling - that is, put Christ in a different setting, and let the story play out. Thus there's nothing akin to Pontius Pilate, or any of that stuff.
Of course, it's more direct when you read Magician's Nephew, and you realize that the Witch was brought into Narnia by men in the first place.
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We have NASA ice cores that show more wild swings in our temperatures and more extremes than we see now.
Well, when we're at the extreme for a temperature swing, that's a little too late to act.
We're already off the charts for something else - carbon dioxide. We know that CO2 plays a huge role when it comes to temperature, life, and oh, a half dozen other things.
Why isn't it enough that CO2 is off the charts (and accelerating off the charts) for the current geologic epoch? We know it's anthropogenic. It's not sustainable to have the rate of CO2 emissions that we have. Why isn't that enough?
Millions of species would survive the entire time, and species diversity would be back where it is today in a geologic eyeblink.
Why is this mindset so prevalent? It's not like the Earth is sticking around forever - life isn't incapable of adjusting to all conditions. It needs water. Do something bad enough to the Earth's atmosphere such that liquid water no longer sticks around, and they all die.
Sufficient amount of radiation would do it, too, though that would require a fair bit more effort. Though silly stories love to make jokes about the resiliency of a cockroach, a sufficiently high dose of radiation really can kill anything. It's that whole "shatter all your DNA" thing.
Heck, if you started life back at the whole primordial ooze thing, it wouldn't have enough time to evolve again. Many models suggest that life has less than a billion years left, and it took life 3 billion years the first time.
But you can't really erase life itself.
Sure you can. The Earth's going to die on its own when solar forcing breaks the hydrologic cycle, but we could probably speed the process up by releasing really really huge quantities of CO2. Burn all the limestone on the planet (hell, we've burned a large fraction of the oil on the planet, so just need a way to power cars off of limestone), send the CO2 levels sky-high, destroy the ozone layer to speed up water disassociation, and the planet would be dead and gone.
(A better approach would be to use those bombs to change the orbit of a nice, large, 100km asteroid to intersect Earth's. And even then, you'd be pretty hard pressed killing everything.)
:) Plus releasing an absolute ton of methane, etc. Add in the complete destruction of the ozone layer (CFCs are our friends) and you could probably strip the planet of water in a few hundred years.
Actually, I think you could probably do it easier. We've already proven capable of increasing the CO2 in the Earth's atmosphere by about 20% or so - almost 100 ppm so far. Just need to repeat that about 20 times over, which would take effort, but is probably not impossible. An economic reason for burning limestone would help.
Life's resilient, but water drives everything. Push the hydrologic cycle off the edge of a cliff, and it isn't coming back.
if they are unable to experience their own existence, then to them they don't exist...
But they are experiencing it. They're just not remembering it. Remembering things allows you to have control over your own experience, but it's not what provides the experience.
You could argue that my responses to people (as non-sensical as they were) were just programmed responses.
A person who experiences complete retrograde amnesia could claim the same thing when seeing film of himself before an incident. It's just lack of memory, not lack of being.
Not to bring up philosophy, of course, as they didn't exactly have the same context as we're describing, but Descartes was right when he said "I think; therefore, I am" - not, "I remember; therefore, I am."
Of course, it's also important to realize that determining "being" is completely impossible. I don't know that anyone else on the planet is conscious - I just presuppose that they are. I know I am, and I know that I still existed even while I was asleep, even though I don't remember it. But I have no way of proving that, of course. I could've been created out of the blue this morning, with the memories I have. So you have to reason "I am now; therefore it is logical that I am the me that was before, and I am the me that will be."
when this mechanism surely ceases functioning just as it would with injury, the experience of the dead person would be the same - nothingness.
I can't see how you can argue that. Your memory isn't who you are - it can be faked, manipulated, damaged, or destroyed. But the important thing about living isn't being able to remember. It's being able to choose. And given that we have no idea where that mechanism comes from, it's impossible to say what happens to it after death.
because with that small part of my brain not working I was literally no longer a person, I didn't exist as a mind - I was just some pile of animated meat.
Hate to comment on this, but if you were a person during that portion, how would you know? You couldn't remember it.
Weather fluxuates. Always has. Always will. To claim that every -previous- shift in climate was completely natural but THIS one is caused by humans...
Atmospheric composition fluctuates, too. Always has, and always will (a lot of it has to do with continental drift, for one). But claiming that every previous shift in CO2 levels is natural, but this one is anthropogenic... makes sense. The spike occurs within the period of anthropogenic CO2 emissions. The amount is consistent with levels of human CO2 production. If you look at ice core data, the last 150 years isn't just an anomaly. It's off the charts. By a lot. (And yes, CO2 levels have been higher in the past, but unless continents have been moving around half the planet while I wasn't looking, that probably isn't the problem).
So now we know we've got an anthropogenic CO2 spike. And now we're seeing a temperature spike. We've got a theory which connects CO2 to temperature which is really, really well founded (by many, many years of agriculture). Unless someone is proposing a theory which explains the temperature spike via other methods while simultaneously explaining why the CO2 spike doesn't cause it, and predicting something the other one doesn't, Occam's Razor says to choose the first one - it's simpler. One cause, two effects. Saying "it's natural fluctuations, that's simpler" isn't right because you're ignoring data - you have to explain why the CO2 rise isn't causing a temperature spike, while simultaneously a different process is.
It's simply bad science to claim that the climate change we're seeing isn't likely to be anthropogenic. Is it anthropogenic? I don't know. Could be that the Martians simply turned up their remote Earth thermostat. Got me. But until a better explanation comes along, this one's the most likely to be true.
Do we understand everything about climate? No. That doesn't mean that the intelligent course of action isn't prudence.
I don't know how I'm going to die, but that doesn't mean that I shouldn't exercise and eat healthy. I could still be hit by a car tomorrow, making all of my work pointless, but it was still the right action to take.
Mercury doesn't really have an atmosphere. Being small and close to the Sun will do that to you. You'll find papers on Mercury's 'atmosphere', but it's not stable. It'd be more properly called an exosphere.
We'd never, ever, ever be able to measure oxygen in Mercury's atmosphere from another solar system. No way.
My only point is that the existence of oxygen in the atmosphere is not a litmus test for life.
Significant oxygen. Oxygen doesn't stay very long in the atmosphere since it binds to, well, everything. It's trivial to measure the atmospheric content of a planet (spectroscopy rules). If you get a planet with say, an oxygen fraction of 10% or more, and temperatures anywhere near reasonable, it's got life.
Right now, if we were looking in on Earth from another solar system, Earth would look very strange - it's the only terrestrial planet with a significant oxygen component. That's the signature for life. Easy enough.
Yes, but bremsstrahlung losses prevent a useful He3-He3 reactor by a wide margin. Brem losses for D-He3 could kill it completely as well, but it's definitely gone for He3-He3.
The benefit of using helium 3 is that you bypass the radioactive element tritium.
The benefit of Helium-3 is that its fusion reaction is aneutronic. This means that the containing vessel wouldn't be irradiated, and it's more efficient - that is, it should be easier to generate ignition with Helium-3 than with a similar fuel that wouldn't be aneutronic.
The downside, of course, is that the reaction involved is D+He3, which means you'd have D+D, and He3-He3 side reactions, and D+D does give off neutrons. And D+He3 takes higher temperatures than D+T. So it's a little - um - daring for the Russians to be saying this, although it's not impossible to believe that given a supply of He3, there'd be economic incentive to build a freaking big fusion reactor.
Seriously though, I hate when people think like this. Maybe by looking out into deep space, we'll discover some new method for easily detecting life which we can then apply to Mars.
The other problem with that quote is that searching for life on Mars is difficult because Mars is very, very close to dead. Mars isn't teeming with surface life. That's pretty much a total given. It might have life clinging in a few underwater reservoirs, but it's not like Earth.
If someone was able to see Earth from a distant star, they'd be able to tell that there's life on the planet in a heartbeat. All you have to do is look for atmospheric oxygen.
We're not looking for marginal life. We're looking for another Earth.
I think this is quite a departure from what is conventional accepted about gravity. The gravitational constant, G, sets the scale for the force of interaction of gravity. It is normally assumed that this value is constant throughout the entire universe.
This isn't a new idea. This idea has been around a long time - it comes from Mach's principle (yes, that Mach) which essentially states that the inertial mass of an object only means anything in context of other objects. Taken with the equivalence principle, this means that gravity depends on the spatial distribution around it.
General relativity does not satisfy Mach's principle - you can create an "empty Universe" which solves Einstein's equations. There have been several modifications to GR to try to satisfy Mach's principle. The simplest one is Brans-Dicke theory, which does exactly what SVTG does - allows G to vary. Brans-Dicke theory is essentially identical to general relativity if the coupling between the scalar field and the tensor field (gravity) becomes infinitely weak. Sounds like SVTG is an extension of Brans-Dicke, allowing a scalar, vector, and tensor component for gravity.
Gravitons here are virtual particles.
I've always wondered why they don't teach what virtual particles are directly in most physics courses. It's very strange. Even when you get to quantum field theory, if you ask "what's a virtual particle?" the answer that you'll get isn't very illuminating - "it's a particle off mass shell." If you read the Wikipedia article on them, you'll see what I mean.
The difference between a virtual particle and a real particle is... well... very little. In any calculation, you usually have a "beginning" and an "end". Like, you say, "an electron scatters off of a photon". You don't know where the electron was, or what it was doing, before the scatter, or what it does after the scatter. We call that electron 'real'.
But you learn in QFT that electron-photon scattering is a two-step process: first, the electron absorbs the photon, the electron propagates a bit, and then the electron reradiates the photon in a new direction. ("bit" here is "really, really, really small"). There's a problem, though - while the electron is propagating, it "isn't really" an electron - that is, it's off mass shell. For a normal electron, its energy is just the quadratic sum of its mass and its momentum. For this "thing", it's not - its energy is a little bit higher than the quadratic sum of its mass and momentum. If you would treat the electron mass as a shell in "energy-momentum" space (where m = sqrt(E^2-p^2)), that "thing" has left that shell. But it still carries all the quantum numbers and interactions of an electron - so we call it a "virtual electron". In a sense, you can think of it as an unstable excitation of an electron, with the "decay time", if you will, being determined by the energy of the "absorbed" photon. High energy, short lifetime, and vice versa.
Now you can see - if the energy is really low, and the lifetime really long, is there any difference between a real and virtual electron? No, not really - it's just a mathematical artifact. If a "virtual electron" interacts with a "real electron", it means in order to calculate it correctly, you need to take into account the interaction that caused the first electron to go off-mass shell.
Taking those interactions into account is called "radiative corrections" - they're first order corrections to QFT, because quantum field theory is perturbative. It starts off by calculating the most important portion of the interaction, and then corrects things later.
So does it matter if a graviton is virtual or not? No, not really. All the exchanges being talked about here are all soft, so the gravitons are very, very close to real.
then why doesn't placing one object in front of another reduce the influence of the body that the second object is shielding against?
Because gravitons don't "push", they only "pull". The only reason we can shield against, say, an electron, is because the electric field can "push" as well as "pull".
Since a gravitational interaction is always purely attractive, any material you put in the middle, to first order, doesn't have any effect. If you've got particle A, B, and C, if A exchanges with C (A==C), and then you put B in the middle, forcing A to exchange with B, then B to exchange that same graviton with C (A==B==C), the net effect is the same - B gets momentum towards A, and C gets momentum towards A because B is now heading towards A.
If you read the article, though, SVTG says it does have an effect - in exactly the wrong way you'd expect. That is, putting matter between doesn't shield gravity, but makes it stronger. And that's how they can explain galaxy rotations - gravity is stronger near the dense central region, and weak farther away. That's also how they explain the Pioneer anomaly - it's not an acceleration as much as gravity gets weaker as density decreases (so the farther you get, the weaker it gets).
The "scalar" part of scalar-vector-tensor gravity makes me think it's related to a Brans-Dicke theory, which was an attempt to satisfy Mach's principle - that is, the mass of an object only makes sense if there's something else around it, so gravity itself should be dependent upon the matter distribution. This theory, also, seems to satisfy Mach's principle.
However, we're still left with the age old question: If gravity is manifest as a particle, why can't we shield against it?
You typically think about stopping "particles" with other particles - like a wall. That's a very classical idea. But in order for a particle to stop at a wall, it needs to interact with that wall - in fact, it needs to either be "absorbed" by the wall, or it needs to be totally deflected by the wall. But in either case, it needs to interact with the wall.
Neutrinos, for instance, don't interact with much, since they only interact via the weak interaction. So we really can't shield from neutrinos that well, although you could build weird gadolinium-doped materials which would probably cut down on the flux of neutrinos more than others. Thankfully, neutrinos interact just like normal matter when they *do* interact, and so you could conceivably shield against them - just not easily.
As for gravitons, though, the situation changes - now you have to ask "can we build a material that interacts with gravitons?" Well, yes - all matter does. But annoyingly, that material itself would produce gravitons as well, and in terms of the SVTG theory, it sounds like it "conducts" them through, too. It's a lot like magnetic shielding - putting a material that interacts with magnetic fields isn't enough to shield a field from you. You need a high-permeability material - that is, one that makes it easier for a magnetic field to flow around you rather than through you.
You can even realize this based on the spin that the graviton has: a graviton would be a spin-2 particle, and any interaction with a spin-2 particle as its mediator must be an attractive potential. Without the possibility of repelling a graviton, you can see that you can't build a shield.
Note that we don't have any fundamental spin-2 particles other than a graviton, so it's understandable that naive ideas don't work.
They've always put invalid IP's in the show
Are they invalid, or reserved ones? I hate it when shows use invalid ones (300.631.42.12 or something like that) when they could just as easily use a reserved IP address. It'd be easy enough to ask any geek "give me an IP address that sounds random, but won't actually be anything", and give them 172.18.101.84 or something similar. (does anyone use the 172.16-31.x.x block?)
Too bad Faraday cages block electric fields, not magnetic fields.
Magnetic shielding is done using highly permeable metals - "mumetal", an alloy of copper, chromium, nickel, and iron, is the standard material used.
It'd be nice if magnetic fields were blocked by a simple Faraday cage. Mumetal's expensive.
Yet Einstein implied as much when he said: "God does not play dice." Many scientists and mathematicians are guided by what they see as divine beauty. If that isn't supernatural causation, what is?
That's not supernatural causation. That's human opinion.
What you're missing is that Einstein was eventually proven wrong. He had an opinion, he tried to justify it, and he failed. Bohr's response is appropriate: "Albert, who are you to tell God what to do?" Which is, curiously, an appropriate response to this entire argument - who are the ID people to tell God how he created the Earth, and humans?
The scientists and mathematicians don't throw out theories based on their "beauty". They throw them out based on evidence. Ugliness is not a kiss of death for a theory, it just makes goofy scientists with an idea of how the universe is supposed to work dedicate their life to trying to figure out how to get around it.
It should be pointed out that natural evolution is also a nondisprovable theory.
No, it's not. What the hell makes you think it is?
The process of evolution is a fact. First off, it's idiotically simple. We've got genes. We pass them to offspring. Those of us who live, pass off our genes to offspring. Therefore future generations look like those who lived. Go fig. Humans have been doing it for thousands of years. We call it dog breeding. Second off, it's observed. We see it. We know the process happens. Regardless of what that process has done, like "the greenhouse effect", no one is challenging that survival of the fittest exists - just what role it played in the development of species.
The theory of evolution - that is, the process by which an amoeba became E. coli became a worm became a fish became a frog became a reptile became a mammal - that's the theory. And that is challengeable - both genetically, anthropologically, and hell, directly! If we really wanted to - and I mean really wanted to - we could look for the reflection of light reflected off of the Earth from distant bodies, thus looking back in time on our own planet. That information is there. It is challengeable. It makes predictions which can be tested.
Intelligent design, however, is not challengeable because it doesn't describe a process. Just a creator. And anyone who's taken journalism class should know that knowing "who" did something doesn't tell you "how" it's done.
The nature of life, the structure of life, and the existance of life can only be explained as an engineering miracle that was created.
That's not an explanation.
In fact, let's get completely specific. There's a decent amount of evidence to suggest that the planet was, in fact, created, and wasn't here at some previous time, right?
So how do you get from that ball of "stuff" (let's call it dust) to the world we have now?
Exactly how?
Saying it "just happened" isn't an explanation. Saying it "was a miracle" isn't an explanation (that answers "why" or "who", not "how").
What you actually want to say is that there is no complete explanation for how life formed. None. Nada. Zero. Zilch. Saying "it was an engineering miracle that was created" isn't an explanation. If ten million years from now, someone finds a clock lying around, and they want to explain how it was made, even if they (rightly) conclude that someone built it, that doesn't answer how it was built. Just who built it.
Likewise, knowing how something was built doesn't necessarily tell you who built it.
Stop trying to offer up "miracle!" as an explanation for "how". It's not one.
Just because you wrote more stuff it doesn't give you the leeway to screw up more...
Uh, so if the Brittanica has an article which says "Bill Clinton was the 41st President of the United States" and that's all, and Wikipedia has a 12-page entry on Clinton which gets his date-of-birth wrong by one day but is perfectly accurate everywhere else, that's okay?
Look at some of the articles listed. The Wiki article (on Robert Burns Woodward) has a detailed breakdown of his life, his career, discoveries, and Nobel prize. The Wiki article's section on his honors and awards - which is just a list - is longer than the entire Britannica article!
So a *pedia article on Slashdot that says "Slashdot is a web site" would be good for you, then?
Hey, it's accurate!
A:Fair use is not a defense to circumvention.
Curiously, though, reverse engineering is. So apparently, you're allowed to circumvent the protection and extract the ISO if you claim you're working on reverse engineering the XBOX 360.
So when Microsoft comes yelling at you, apparently you can yell "dude, it's okay. I'm a hacker."
You mean, other than the fact that Lewis actually said that Nephew coming first is the order they're supposed to be read?
Did you happen to hear the multiple times that they call humans "Sons of Adam and Daughters of Eve" ?
That's just terminology. It doesn't make it an allegory of Christ. I could stick those terms into any random fantasy setting, and it wouldn't mean anything there, either - other than someone wanted to use a phrase that sounded more regal than "men" and "women".
Perhaps you missed the part saying that Aslan died for what essentially are the sins of another.
There's the kicker. Then again, the original poster is correct that it's not a simple allegory for Christ. It's a retelling - that is, put Christ in a different setting, and let the story play out. Thus there's nothing akin to Pontius Pilate, or any of that stuff.
Of course, it's more direct when you read Magician's Nephew, and you realize that the Witch was brought into Narnia by men in the first place.