Um, can't we make a sustained nuclear fusion reaction right now?
In every particle accelerator since the 70's...
But it's a negligent yield.
As for energetically and commercially viable reactors, recently neutrons were detected from a fusion pellet using Z-pinch induced hohlraum radiation (ICF). [ press release]
AFAIK this variant on the ICF method holds at least as much promise for a viable reactor as MCF (The Tokamaks and ITERs of the world).
But I must disclaim that I am a grad-student researching Z-pinchs, so I have a natural bias...
It's one thing to assert evolution through unknown mechanisms (as Darwin did), and another to identify and model these mechanisms.
If this is true, and if this is widespread (at least in prokaryotes), than this may be a significant addition to the understanding of epigenetics's role in evolution. Very much NOT 19th century.
The first principle for quantum mechanics, the wave equation is not well understood.
It is understood well enough to numerically predict the atomic, nuclear and radiation physics for the particles envolved in the relevant energies.
For the purpose of the experiment at hand, this is as much as a physicist needs.
Additionally the.. nuclear force... QCD... is computationally so expensive to be currently untractable...
w.r.t. general QCD and nuclear physics - agreed. However, for the purposes of DT fusion actually all one needs is the cross section as a function of velocities (Gamow's peak)... and that's it.
I'm NOT saying either QCD and/or nuclear physics are not viable, active research areas, I'm just saying neither light-elements fusion in general, nor these experiments specificly, are even remotely being affected by the still open problems.
And finally the characterization of plasma temperature, density required, and time to hold to cause fusion is not well known. This is an area of intense research where alot of unknown effects are still being investigated.
Actually this is incorrect. The temperature, density and time required are connected by the lawson criterion. It is derived from undergrad-level plasma-collision theory and the cross-sections for fusion, which are well-known.
Which is again NOT to say that there are no (quite severe) plasma physics problems, scientific as well as technological, on the way to comercially viable controlled fusion, but these problems have nothing whatsoever with our current limits of understanding quantum effects, which were the OP topic. (My guess is that the OP perhaps confused quark-gluon plasma with fusion plasma. )
Besides, the reaction that occurs in the fusion chamber of the power center is not a bomb, it is controlled fusion, much more elegant (and more expensive).
In ICF the goal is a submilimeter scale thermonuclear explosion. A tiny bomb is indeed an accurate description.
It is indeed safe b/c the quantities are small: nuclear energy density is ~10^6 higher than chemical, so if one explodes 10^-6 the amount of, say, coal that is burned in a usual generator in a second, one gets the same power, which we know how to control (puting aside the nutronic difficulty).
...but rather to setup and run an experiment that could teach them new things. (Oh, and generate oodles of research papers.)
That is what is usually called "science".
Usually, in these kinds of basic "understanding" tests
That is what is usually called a "scientific experiment".
(which is still where we really are in terms of our understanding of quantum effects)
WTF are you talking about ? This is dense plasma physics, at these energies the only quantum effects are atomic, QED, and, hopefully, nuclear-fusion physics: the first principles for all are rather well understood.
In the immortal words of A. nonymous: Don't talk nuclear when you don't know shit
and it can be considered as a quantum blurring of the deuterium and tritium nuclei within the muon cloud
Or, to put it shortly: \mu causes two nucleons to get close enough so that tunnelling can occur.
I've wondered what might happen in a Bose-Einstein condensate of fusionable materials
first, AFAICT, one can't make BEC out of charged particles: so that means that one needs to cool ATOMS rather than nucleons: but for fusion one needs to overlap the nucleons' wavefunctions, and they occupy a minute part of the atoms'.
second, for BEC one needs bosons, i.e. one cannot use D, but can use T. But AFAIK there is no energetic gain from T-T reaction.
This definitely doesn't bound velocities. It bounds accelerations. While this would matter for short distances, for extremely long distances, the acceleration period really wouldn't matter all that much.
Playing a nitpicky purist for a minute, this does set a theoretic bound for both velocities and hence lorentz factor and time.
If, for long distances, a ship does not (de)accelerate continuously, then this simply means the theoretic bound is not reached.
But anyway this is just emantics. Like you've said, this is of no practical concern.
If we can levitate frogs using diamagnetic repulsion, effectivly reducing acceleration by 1g throughout their tissues, could we not build similar containers for humans allowing very high acceleration?
It doesn't matter which way you do it, if the crew's mean acceleration is smaller than the ship, the crew will stay behind... different average accelerations are impossible.
Using problems as an excuse for not doing anything, stating current limitations as reasons not to even try to overcome or deal with them is not wizdom. It's just plain-old, narrow-minded intelectual cowardice.
Yes, there are problems. Deal with them. Yees, there are obstacles. Don't sit and whine in your little corner of the universe like a frightened little kid - overcome them.
In science, and I had the honor and priviledge to know and study from great scientists personally, everything which was not disproved is considered possible. If it's possible and important, than it should be tried. If it's deemed impossible and important, sometimes it should be tried also.
You think space-colonization is impossible. Perhaps you're eventually right (though not for the feeble excuses you gave): But if humanity will not at least TRY, at least research and experiment and DO, not just moap and whine about what is hard to do or imagine - then we will all, as a specie, be as narrow-minded and cowardly as your post.
And BTW, IMHO, if judging from past experience: humanity, as a specie, eventually takes after our intelectually-brave. So I still have hope we wouldn't curl-up and die.
There is a universal speed limit - c - but there is no lower bound on the amount of proper time it takes to get from one place to another.
Although I generally agree with the spirit of your message, this specific statement is not accurate:
First, there's a biophysical upper bound on acceleration: the body cannot concievably withstand much more than several g's for long. This limits your Lorentz factor.
Second, once v/c ~.93-4 interstellar dust, and eventually gas, starts being a major concern. At these velocities a shield is essentual, which limits you cargo and fuel mass. The closer a ship is to C, the larger a shield. (Plus, gas and dust collisions also reduce ship momentum: over long voyage this is effectively a very non-linear viscosity...). The trade-off and viscosity limits spaceship velocities so that time-dilations much more than 10 are not feasible.
Then there's the nuclear capability of Israel.... can't imagine where that came from.
Maybe you need to work your imagination a little harder.
Israel's capabilities are the result of both its having a high-skilled personnel fleeing Europe and its cooperation with France (first) and South-Africa (later).
In fact, the US tried to deter the Israelly efforts from the start. Israel gained nuclear capabilities inspite of the US efforts.
Slashdot Mirror
not suffer from the "I read it on the internet" stigma. People are more likely to believe something if it doesn't glow when they read it.
I have a great bridge to sell, excellent condition. Don't just believe this glowing msg, read my paper booklet !
may be a great fertilizer, but it doesn't mean one should eat it as well as the real fruit
Lookup the Broken window fallacy
And this differs from the methodology of economics in what way?
A real practical difference is that changes in economical thinking affect the economy - thereby affecting (yet) unmeasured values.
This feedback is not, of course, valid in astrophysics.
Interestingly, even fluid dynamics equations are applicable in some cases
Ref, Link ?
Although I can easily think-up hypothetical examples myself I wonder what the real uses are.
(I'm a physicist, not an economist)
Um, can't we make a sustained nuclear fusion reaction right now?
...
...
In every particle accelerator since the 70's
But it's a negligent yield.
As for energetically and commercially viable reactors, recently neutrons were detected from a fusion pellet using Z-pinch induced hohlraum radiation (ICF). [ press release]
AFAIK this variant on the ICF method holds at least as much promise for a viable reactor as MCF (The Tokamaks and ITERs of the world).
But I must disclaim that I am a grad-student researching Z-pinchs, so I have a natural bias
I assume this is because marketing people are better at marketing their book about marketing than they are at writing a good book.
IOW: all marketteers really want to know is how to sell utter crap for the price of 24K gold.
And marketting-books authors MUST excell at that
(On a more serious note, yeah, I know there's a lot more to marketting than that - but it's hard to seperate chaff from grain)
It's one thing to assert evolution through unknown mechanisms (as Darwin did), and another to identify and model these mechanisms.
If this is true, and if this is widespread (at least in prokaryotes), than this may be a significant addition to the understanding of epigenetics's role in evolution. Very much NOT 19th century.
( Disclaimer: IANAB )
As an Israelly, I would say one needs smart bread especially on Passover.
I can see the adds now: "your merchandise will evade religious/government inspectors by itself ! A fortune saved in bribes !"
Really? I usually notice a huge performance decrease when using Wine. Blurred vision, slurred speech, light-headedness, a sense of euphoria.
Performance decrease for men, but increase for women : You've been utilising wine on the wrong client.
-- Premature optimization is the root of all evil.
Already
The first principle for quantum mechanics, the wave equation is not well understood.
It is understood well enough to numerically predict the atomic, nuclear and radiation physics for the particles envolved in the relevant energies.
For the purpose of the experiment at hand, this is as much as a physicist needs.
Additionally the
w.r.t. general QCD and nuclear physics - agreed. However, for the purposes of DT fusion actually all one needs is the cross section as a function of velocities (Gamow's peak)
I'm NOT saying either QCD and/or nuclear physics are not viable, active research areas, I'm just saying neither light-elements fusion in general, nor these experiments specificly, are even remotely being affected by the still open problems.
And finally the characterization of plasma temperature, density required, and time to hold to cause fusion is not well known. This is an area of intense research where alot of unknown effects are still being investigated.
Actually this is incorrect. The temperature, density and time required are connected by the lawson criterion. It is derived from undergrad-level plasma-collision theory and the cross-sections for fusion, which are well-known.
Which is again NOT to say that there are no (quite severe) plasma physics problems, scientific as well as technological, on the way to comercially viable controlled fusion, but these problems have nothing whatsoever with our current limits of understanding quantum effects, which were the OP topic.
(My guess is that the OP perhaps confused quark-gluon plasma with fusion plasma. )
Besides, the reaction that occurs in the fusion chamber of the power center is not a bomb, it is controlled fusion, much more elegant (and more expensive).
In ICF the goal is a submilimeter scale thermonuclear explosion. A tiny bomb is indeed an accurate description.
It is indeed safe b/c the quantities are small: nuclear energy density is ~10^6 higher than chemical, so if one explodes 10^-6 the amount of, say, coal that is burned in a usual generator in a second, one gets the same power, which we know how to control (puting aside the nutronic difficulty).
That is what is usually called "science".
Usually, in these kinds of basic "understanding" tests
That is what is usually called a "scientific experiment".
(which is still where we really are in terms of our understanding of quantum effects)
WTF are you talking about ? This is dense plasma physics, at these energies the only quantum effects are atomic, QED, and, hopefully, nuclear-fusion physics: the first principles for all are rather well understood.
In the immortal words of A. nonymous: Don't talk nuclear when you don't know shit
I'm not a real geek :)
...
maybe that was too harsh
raised in the US, born in Israel? Maybe that explains it? Well I did grow up on ST:TNG
As I grew up in Israel, I don't think it does. However, the time difference may explain it: STTNG ran [1987-94], while Cosmos was made in 1980.
Lets count, who here knew of the word "Googol" prior to this posting?
I would guess quite a lot, as Carl Sagan mentioned it in his "Cosmos" pop.sci. series.
And show me a real (western) geek, of the appropriate age, which did NOT see "Cosmos". Maybe not a zero-measure set, but quite close
Except decimal, that is
Can you point me to the design ?
You mean something based on this ?
and it can be considered as a quantum blurring of the deuterium and tritium nuclei within the muon cloud
...
Or, to put it shortly: \mu causes two nucleons to get close enough so that tunnelling can occur.
I've wondered what might happen in a Bose-Einstein condensate of fusionable materials
first, AFAICT, one can't make BEC out of charged particles: so that means that one needs to cool ATOMS rather than nucleons: but for fusion one needs to overlap the nucleons' wavefunctions, and they occupy a minute part of the atoms'.
second, for BEC one needs bosons, i.e. one cannot use D, but can use T. But AFAIK there is no energetic gain from T-T reaction.
But I'm no physicist.
I am. But I can still be wrong
This definitely doesn't bound velocities. It bounds accelerations. While this would matter for short distances, for extremely long distances, the acceleration period really wouldn't matter all that much.
Playing a nitpicky purist for a minute, this does set a theoretic bound for both velocities and hence lorentz factor and time.
If, for long distances, a ship does not (de)accelerate continuously, then this simply means the theoretic bound is not reached.
But anyway this is just emantics. Like you've said, this is of no practical concern.
If we can levitate frogs using diamagnetic repulsion, effectivly reducing acceleration by 1g throughout their tissues, could we not build similar containers for humans allowing very high acceleration?
It doesn't matter which way you do it, if the crew's mean acceleration is smaller than the ship, the crew will stay behind
Using problems as an excuse for not doing anything, stating current limitations as reasons not to even try to overcome or deal with them is not wizdom. It's just plain-old, narrow-minded intelectual cowardice.
Yes, there are problems. Deal with them.
Yees, there are obstacles. Don't sit and whine in your little corner of the universe like a frightened little kid - overcome them.
In science, and I had the honor and priviledge to know and study from great scientists personally, everything which was not disproved is considered possible. If it's possible and important, than it should be tried. If it's deemed impossible and important, sometimes it should be tried also.
You think space-colonization is impossible. Perhaps you're eventually right (though not for the feeble excuses you gave):
But if humanity will not at least TRY, at least research and experiment and DO, not just moap and whine about what is hard to do or imagine - then we will all, as a specie, be as narrow-minded and cowardly as your post.
And BTW, IMHO, if judging from past experience: humanity, as a specie, eventually takes after our intelectually-brave. So I still have hope we wouldn't curl-up and die.
There is a universal speed limit - c - but there is no lower bound on the amount of proper time it takes to get from one place to another.
.93-4 interstellar dust, and eventually gas, starts being a major concern. At these velocities a shield is essentual, which limits you cargo and fuel mass. The closer a ship is to C, the larger a shield. (Plus, gas and dust collisions also reduce ship momentum: over long voyage this is effectively a very non-linear viscosity ...). The trade-off and viscosity limits spaceship velocities so that time-dilations much more than 10 are not feasible.
Although I generally agree with the spirit of your message, this specific statement is not accurate:
First, there's a biophysical upper bound on acceleration: the body cannot concievably withstand much more than several g's for long. This limits your Lorentz factor.
Second, once v/c ~
Then there's the nuclear capability of Israel.... can't imagine where that came from.
Maybe you need to work your imagination a little harder.
Israel's capabilities are the result of both its having a high-skilled personnel fleeing Europe and its cooperation with France (first) and South-Africa (later).
In fact, the US tried to deter the Israelly efforts from the start.
Israel gained nuclear capabilities inspite of the US efforts.