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a reply to: Pirvonen
Neutrinos pass through even more matter, but neutrons can go through quite a bit. The source I cited a few posts back said that neutrons can pass about 2/3 of a meter through solid rock, and that's an average so individual neutrons may travel less or more distance. Most neutrinos of course pass through the entire Earth.

a reply to: ErosA433
Thanks for fielding the astronomy question about the nova; I was hoping you would with your astronomy background. Since you didn't mention electric universe, KryZma may not be satisfied with your answer, but I thought it was very good.

originally posted by: Pirvonen

originally posted by: ErosA433

... for neutrons a shutter doesn't do very much, neutrons can pass through a significant amount of material

Are you sure you don't mean neutrinos here? Neutrons, although electrically neutral and thus more penetrating than charged alphas or betas, are massive and do interact with matter. Something dense.

Yes, definitely neutrons

While it is possible to stop neutrons, the approach is typically to use a material with a high hydrogen density within the molecule/material, or something else like boron. These light elements have a high neutron capture cross section, or can thermalize the neutrons (slow them down lots till eventually they either decay or are captured)

Neutrons being electrically neutral is part of what causes this high level of penetration. For our experiment underground, our detector uses PMTs for photon detection, now glass is quite radioactive (dont worry, not THAT radioactive) for a rare event search, and thus how we reduce the backgrounds from PMTs creeping into the detector is to offset the PMT from the detector volume on the end of a 20 inch long, 8 inch wide acrylic light guide.

While PMT glass doesn't produce neutrons directly, it produces alphas... these alphas can interact and produce neutrons.

Not only those 20 inch long light guides, we also worry about muon spallation events which at a depth of 6800ft below the surface in a hard rock mine, is a very low flux, muons interacting in the rock can produce bursts of neutrons. We shield these by using a 8 meter diameter water shield tank Instrumented with PMTs. The PMTs are to observe the muons that produce Cherenkov light, and the water is to stop the neutrons. A combination timing can grately reduce the background impact on the Dark Matter search.

We also WANT to use a calibration source, since Dark Matter will have the same signal inside the detector as neutrons... so how do we put neutrons inside the detector through all that shielding? We go high intensity. We do this using an AmBe source. It works by the Americium producing gammas which are higher energy than the neutron binding energy in the Beryllium. So we get a nice bit of AmBe alloy/mixture and put it near the detector.

This being said, the storage location for our source (not approved for use yet, still under review) is a location that is about 70 ft away through rock. Sounds fine right? Well lets just say that experiments at the lab also doing dark matter searches are making us do simulations to show the impact at their experiments is less than their normal backgrounds... and yes... you would be surprised how far neutrons get in the simulations... talking many hundreds of feet here.


Also for neutrons interacting with something dense is not typically a good way to shield things, because they tend to cause activation. Most elements when you add more neutrons to, can be unstable, so with a neutron source, incasing it in lead or concrete, results in a lovely mix of radioactive isotopes, most of which are short lived (1-2 month half life) the rest however can be quite long lived. Most neutron sources / beams are thus surrounded by paraffin wax coffins, or light materials like hi-density poly ethylene or water.

Hopefully this is helpful, it is directly related to my work so haha sorry for the page of text. Hopefully presented in a clear and interesting manner


Neutrinos of course like to go through everything

originally posted by: Arbitrageur
Thanks for fielding the astronomy question about the nova; I was hoping you would with your astronomy background. Since you didn't mention electric universe, KryZma may not be satisfied with your answer, but I thought it was very good.

Thanks - not sure it will be accepted either. Truth is, iv not done any n-body or gas simulations, or have a PhD directly in that field, I just have a basic run down as to why the material accretes and the kinds of systems they are. The shape of the gas being thrown off and lit up in these nice pictures however I can only speculate why it isn't spherical. But that speculation does form the potential for many parameters that could easily in my opinion give you a wide variety of shapes Nature is surprising and interesting that way

originally posted by: ErosA433

originally posted by: Pirvonen

originally posted by: ErosA433

... for neutrons a shutter doesn't do very much, neutrons can pass through a significant amount of material

Are you sure you don't mean neutrinos here? Neutrons, although electrically neutral and thus more penetrating than charged alphas or betas, are massive and do interact with matter. Something dense.

Yes, definitely neutrons

While it is possible to stop neutrons, the approach is typically to use a material with a high hydrogen density within the molecule/material, or something else like boron.

The soviets used paraffin their tanks to protect against neutron bombs.

originally posted by: Arbitrageur


You're right that positrons are cheaper than anti-protons, but I wouldn't say cheap:

Antimatter_cost

In 2006, Gerald Smith estimated $250 million could produce 10 milligrams of positrons[56] (equivalent to $25 billion per gram); in 1999, NASA gave a figure of $62.5 trillion per gram of antihydrogen.

So yes $25 billion a gram is cheaper than 62 trillion dollars a gram, but what else costs even 25 billion dollars a gram? I'm not sure how much the costs have come down since 2006 but in this paper the authors suggest that antimatter may never be very economical to produce:

Antimatter_paper

A study by the RAND Corporation gives a cost estimate of $500 to 1000 million for a prototype factory providing 10 to 100 micrograms (of anti-protons or anti-hydrogen), and $5 to 15 billion for a full production factory with an output of about 10 mg per year[4]. As a consequence, civilian applications of antimatter for power production are very unlikely.

For Tony Stark, cost might be no object and he apparently has more money than he knows what to do with, but he is a comic book character. In the real world, cost matters.

well these gents with thier papers are supersceded by subsequent developments. I reject thier reality and substitute my own.

we now have new forms of accelerator that are desktop foot print and produce more positrons than the big machines do. This is new technology that those authors had no clue about. it is small but puts out positrons easily in vast quantities. Compared to big accelerators this has the requirements and ease of a microwave oven.

now i am talking about the economics and quantity issues. and not the gamma rays vs more useful byproducts of anti-protons or problems of storage. you were absolutely spot on on those issues.

(they have to be stored because if you put an anti-proton generator on a ship, you obviously have a power source putting out twice the energy needed to make anti-protons in the first place and should instead use that power source to power your engines.)

a reply to: stormbringer1701

What if we use the particle as a means of "storing" the anti-matter/ positron? We just need to develop a cost-efficient method of extracting it. Then put it into direct use after it's extracted, no storing, just consuming it.

originally posted by: IAmTheRumble
a reply to: stormbringer1701

What if we use the particle as a means of "storing" the anti-matter/ positron? We just need to develop a cost-efficient method of extracting it. Then put it into direct use after it's extracted, no storing, just consuming it.

the issue is this:

we know of no way to make an antimatter particle without also making a regular matter particle so the process is always no better than 50 percent efficient. in reality due to thermodynamics it is worse than 50 percent efficient.

so lets say you make 400 watts or horepower or joules or whatever of usable energy. in doing so you have to have spent 800 watts or what ever. so you are taking 800 watts and only getting 400 watts out of it. You'd always be better off just using the 800 watts for propulsion directly. thats the problem with making your antimatter as you go if you are going for a pure antimatter annihilation drive.

but like a car burning gasoline or even using a battery it does not matter so much if your process for getting the energy to run the car takes more energy than the gas gives the car or the battery gives the car because the point is your storage has little mass and yet you can use the energy at a better rate in the car than in the production of that car or the gas. so if you have a bottle of antimatter it's like a full gas tank or battery.

also the problems of antimatter annihilation as a direct source of propulsion or electricity generation is that only small fraction of the results of annihilation are directly usable for that. most of it is wasted as stuff you can't use. fusion reactions suffer from this problem to a lesser extent but at least fusion reactions with certain reactants produce 66 percent usable energy in the form of energetic charged particles and nuclei.

Depending on the antimatter involved you get reactions which produce no charged particles to a few charged particles, a lot of photons and neutral ghost particles of which some will decay to charged particles in about 1.6 kilometers of travel which you could also harness with a 1.7 km long engine but that radiation is also spherical so most of it won't appear in your engine anyway.

i think the best use of antimatter for now would be to use it to do one of three things:

1. initiate fusion
2. initiate fission.
3. use it to heat a working fluid or propellant mass.

when used this way you only need a really small amount measured in micrograms or nanograms to get to mars or even the edge of the Oort cloud.

1. the max speed of any rocket is (in an ideal case) limited to 2 times the exhaust velocity which may be up to light speed minus the tiniest fraction you can manage.

2. ion drives can continue to accelerate until they reach the 2X maximum exhaust velocity limit (mentioned above) of which their technology allows.

3. They require very little fuel per unit of time to do that.

3. they can do that to their exhaust velocity limits so long as they have fuel.

4. if they have the gas they can conceivably accelerate to large fractions of the speed of light and keep it up for years and years.

5. they can be powered by anything that produces electricity. batteries, solar panels, electro-thermal converters, fission, fusion, antimatter, off board lasers, you name it.

it's really fun to read your science fiction scenarios.. almost better than watching Star Trek

so... about making "opposite of" something...

The main idea in making antimatter is just getting enough energy in a collision to allow the particles to be made. If you get electrons going fast enough and throw them at a piece of material called a target, preferably made out of atoms that have a large atomic number, you will have a shower of electrons, positrons (anti-electrons) and photons. The details are as follows:

A high-energy electron, when it comes near a nucleus, will feel the electric field of the charged nucleus, and be deflected in its path. The larger the charge of the nucleus, the more frequently this deflection will happen at large angles. When a fast electron is diverted from its straight-line path, it radiates some of its energy away as photons. High-energy photons, when they come near another nucleus, can spontaneously turn into an electron-positron pair (conserving charge and the "number of electrons", which both add to zero since a positron has positive charge and is an anti-electron). The second nucleus is there to exchange energy and momentum with, otherwise you cannot start with a photon (zero mass) and end up with two objects with mass and conserve energy and momentum.

If the electron and positron thus produced have enough energy, they can undergo scattering with more nuclei, radiate photons which can pair-produce more electrons and positrons, creating a whole "shower" of electrons, positrons, and photons. Positrons then can be separated away with magnets and collected in particle accelerators.

At Fermilab, we make antiprotons all the time. The process is similar, where protons are thrown with high energy into stationary targets. Most of the stuff that gets made are pions, but every now and then you'll get an antiproton. Instead of photons, the mediating force carriers are gluons, which carry the strong nuclear force. Many gluons must be exchanged because you need to create three antiquarks to make up an antiproton, and get lucky enough for them to stick together in an antiproton.

well... in my picture....
just because the trail looks the same, but bends in the opposite way in an magnetic field, it does not mean it's something new!
call it anti-something if you like, but don't treat it as the usual stuff. it is not! it's an anomaly and that's the reason it's not so common like the other, real stuff...
I also dislike the charge 1 only as "property" of an charged particle.

think about how to "overload" charges.
talking about mathematical description of the observed inside a prison of theory won't change a thing !!!

originally posted by: KrzYma
well... in my picture....
just because the trail looks the same, but bends in the opposite way in an magnetic field, it does not mean it's something new!

So, you're saying it's not something new?

call it anti-something if you like, but don't treat it as the usual stuff. it is not!

So, you're saying it IS something new?

Which is it? You seem to be contradicting yourself, or at the very least, you're not being clear.

it's an anomaly and that's the reason it's not so common like the other, real stuff...

So it's not real?

I also dislike the charge 1 only as "property" of an charged particle.

I don't know what you mean by "only" a property. What should it be instead and what measurable difference would it make in observations or models if your different view was correct?

think about how to "overload" charges.

What does that mean?

talking about mathematical description of the observed inside a prison of theory won't change a thing !!!

If mainstream science is wrong why not publish a paper with your better model? Because you don't have a better model?

These vague comments of yours certainly aren't changing anything.

a reply to: stormbringer1701
When I said "I'm not sure how much the costs have come down since 2006" I meant just that, which infers that I suspected the costs have come down but I didn't know how much and it wasn't important enough for me to spend a lot of time searching for updated cost figures. So while I don't doubt the assertion that costs are now lower, even after reading your post I still have no better sources or figures for current costs, so I'm still inclined to use the 2006 source I posted until I have a better one.

Even if the cost of anti-protons has been reduced from $62 trillion a gram to only $1 trillion a gram which would be a 62-fold reduction, $1 trillion a gram would still be very expensive.

How would should I begin building a dyson sphere around the sun

What materials is best for the job
And do we have enough materials
And how much heat can solar panels even take

Do we have the capabilities for it but not the funds ?

well there have been several exciting developments in both positron production and in anti-proton production and trapping. they can now ship anti-proton samples around the world to various universities or other labs and facilities. the record for containment (single anti-proton) is 57 days. the production record is now several trillion anti-protons. and the thing is this was not a purposed designed apparatus. the researcher merely made something that "would do." he said he and colleagues are considering engineering an actual purpose built and designed from the ground up production machine and starting a business providing anti-protons commercially.

as far as positrons go as i said there are devices; essentially the size of half a big ol' business desk that can pump out positrons in vast quantities all day long. is quadrillions gazzilions a lot? mass quantities?

phys.org...

we are not there yet; i understand that. But the capacity to store and make antimatter is expanding far faster than predicted.

And if you have a few nanograms of anti protons and you can store them in quantity for about 90 days you can fuel an ICAN II or AIMSTAR spaceship for a trip to mars in 39 days both ways plus a few days for doing science and exploration on station. You can justify Building and manning facilities on Mars because you can make regular passenger and cargo service a real thing.

57 days is more than half way to that goal if you could do it for quantities of antimatter as opposed to single anti-protons.

that positron production technique should also work for anti-protons if you up the power involved. we are learning new ways to get the same power as these miles long world class facilities in smaller and smaller packages.

www.iflscience.com...

originally posted by: Spacespider
How would should I begin building a dyson sphere around the sun

What materials is best for the job
And do we have enough materials
And how much heat can solar panels even take

Do we have the capabilities for it but not the funds ?

Us synergistic technologies to bypass the normal economic considerations.

robotic off world mining. robotic off world materials processing. robotic construction. use robots to gather the materials, process the materials, replicate themselves a few times per unit and then after successful replication is accomplished they go to making solar collectors instead of having people do it. as each succeeding generation of bots goes to work your number of workers will grow geometrically. you need safety rules built in to prevent them from disassembling things you don't want disassembled (like people, spaceships, planets, each other) and to stop when the job is done.

for the dyson sphere you don't need a solid sphere. that is wasteful and likely impossible from a structural properties and mechanical limits of materials angle. just float a vast number of formation flying collectors in a spherical orbit around the sun.

originally posted by: KrzYma
well... in my picture....
just because the trail looks the same, but bends in the opposite way in an magnetic field, it does not mean it's something new!

Sooo what is it exactly?

You appear to be of the opinion that science blindly accepted anti-matter as being a thing straight away and did absolutely no tests on it. The truth is that the model for anti matter is very well motivated, and comes along with a very large number of experiments and tests that can be done in order to examine the very fundamentals of its nature and the models also....The mass of it has been measured with great accuracy, and as near as can be assessed, it is the same as the electron... its charge also... and it is exactly the same to better than 10^-8, same for the charge, positive, but the same value to better than 10^-7

So care to do something real? and propose something rather than elaborately saying we dont know anything while making ltos of contradictions like Arbitrageur pointed out?

call it anti-something if you like, but don't treat it as the usual stuff. it is not! it's an anomaly and that's the reason it's not so common like the other, real stuff...

An anomaly that we can reproduce and do measurements with at will... it is produce in nature too, there are isotopes that produce positrons... So you are saying that we have to invent a whole new system for radioactive decay too? Your model is getting even more elaborate, It would seem. So thats nuclear physics and particle physics in the can? (sure they are related but, to throw away the work of over 100 years... you might want to actually show something more than just acting like some kind of 'particle physics prophet who talks in rhyme'

I also dislike the charge 1 only as "property" of an charged particle.

think about how to "overload" charges.
talking about mathematical description of the observed inside a prison of theory won't change a thing !!!

Talking about something being the wrong model and not presenting anything plausible other than saying 'I dont like x property' and 'you are all wrong, you know nothing' is not going to change a thing either. So how about... stomping the pavement, doing the work, and get an actual understanding of what you are trying to deny and then produce a nice paper, a coherent argument and come back and discuss it.

o7

just say if i take a positron and touch it with an electron and the act causes both to disappear and irradiates me with gamma rays then it serves as pretty good evidence that dirac and others were right and kooks are wrong.

a reply to: Arbitrageur

Yes, I need to simplify what I've said. Sounds logic to me but I see the confusion for you...
so..
"just because the trail looks the same, but bends in the opposite way in an magnetic field, it does not mean it's something new"

I mean there is no creation happening, a change yes, but not as an positron comes into existence from nothing.

that's how I see it,
and if you explain to me what an electron really is, where it gets the charge from, why is it always in a state of movement, and not just saying "a charged particle", I will listen...
I hope after 200 years of discussing, probing and experimenting, ( comparing to my few years just thinking about ) your theory should be able to explain it, is it ??
There is a nice description of the measurements done with it but nothing more >>

YES, I will show you the picture after it's painted and not before.



"think about how to "overload" charges."
here "I" is missing...
I think about how to "overload" charges.

"talking about mathematical description of the observed inside a prison of theory won't change a thing !!! "
this sounds like something against you, what I mean is something different.

I can not work with any existing theory based on mathematical concept that allow ZERO or NEGATIVEs
there is no negative distance or negative field. It simple existence makes it so.
There is "negative direction" compared to something and "opposite rotation" compared to something,

however...
All this confusion because of an missing "I"

funny thing is, how quickly you switched to aggressive defense and attack my words one by one...
Do my words feel aggressive to you if you read my text ?

originally posted by: Spacespider
How would should I begin building a dyson sphere around the sun

What materials is best for the job
And do we have enough materials
And how much heat can solar panels even take

Do we have the capabilities for it but not the funds ?

What do you want to do with it? The idea is it would collect energy then transfer it to where it's needed. We have the ability to create satellites which can collect energy and could use microwaves to beam it to the Earth's surface, and eventually we might do something like that but there are some issues:

1. Can it be done safely? You know what happens to food in a microwave oven, right? Presumably we'd make a large collecting array in the desert somewhere but that has its own set of problems if you beam it to a place where there's no population nearby, because it costs money to transport the electricity from where it's collected to where it's needed.

If you beam it closer to where it's needed, if the beam gets a little out of alignment from the receiver then you're aiming powerful microwaves at the nearby population.

2. Can it be done economically? What are the costs of building the satellite and rocket and launching it, what's the expected life and maintenance costs and costs per unit energy delivered, versus alternative sources of energy? Capitalism has a way of making things with an economic benefit happen. When fossil fuels get more scarce the Dyson satellites might be more economically justifiable.

originally posted by: stormbringer1701
is quadrillions gazzilions a lot? mass quantities?

Petawatt laser? How many watts in a petawatt? I suppose the article implies lower capital costs but still, petawatt laser doesn't sound like it's that cheap to run. It still doesn't tell me how much a gram or microgram of positrons would cost to make.

originally posted by: stormbringer1701
that positron production technique should also work for anti-protons if you up the power involved.

Yes so lower capital costs does seem inferred but still, larger than petawatt? Doesn't sound cheap.

originally posted by: KrzYma
All this confusion because of an missing "I"

Adding the "I" doesn't really resolve any confusion about the meaning.

funny thing is, how quickly you switched to aggressive defense and attack my words one by one...
Do my words feel aggressive to you if you read my text ?

Aggressive defense and attack? I thought I was asking for clarification of what you're talking about, but it seems like you're the one always attacking mainstream science. Well I never claimed mainstream science is perfect, it's not and it needs some improvement and that's part of what makes it what it is.

The question is, what improvements does it need and how do we know that? Can we confirm any new ideas that will make it better?

If your comments aren't clear enough to help reach that goal, instead of worrying about whether your comments are being "attacked", why not address the issues, like present your model that works better than the one you're complaining about?

in the dead horse category:

factors to consider are the increasing ease with which antimatter can be made, the almost certain commercialization of it will drive down costs. SLAC scientists are already considering publicly going into the world wide anti-proton supply biz. there is no reason to assume prices will not continue to come down and do so drastically if the market forces demand it.

secondly when you speak of grams of antimatter you are aiming towards true interstellar uses now whereas the first antimatter involved drives and missions will require nanograms and micrograms. worst case scenario would then be billions of dollars. not small change but not unheard of for international or even national projects.

and again i assert that the economics will change drastically for the better when you can rent a bottle of the stuff if you are a moderately sized university or company. Thats what the SLAC guys are talking about.

originally posted by: Arbitrageur

originally posted by: Spacespider
How would should I begin building a dyson sphere around the sun

What materials is best for the job
And do we have enough materials
And how much heat can solar panels even take

Do we have the capabilities for it but not the funds ?

What do you want to do with it? The idea is it would collect energy then transfer it to where it's needed. We have the ability to create satellites which can collect energy and could use microwaves to beam it to the Earth's surface, and eventually we might do something like that but there are some issues:

1. Can it be done safely? You know what happens to food in a microwave oven, right? Presumably we'd make a large collecting array in the desert somewhere but that has its own set of problems if you beam it to a place where there's no population nearby, because it costs money to transport the electricity from where it's collected to where it's needed.

If you beam it closer to where it's needed, if the beam gets a little out of alignment from the receiver then you're aiming powerful microwaves at the nearby population.

2. Can it be done economically? What are the costs of building the satellite and rocket and launching it, what's the expected life and maintenance costs and costs per unit energy delivered, versus alternative sources of energy? Capitalism has a way of making things with an economic benefit happen. When fossil fuels get more scarce the Dyson satellites might be more economically justifiable.

originally posted by: stormbringer1701
is quadrillions gazzilions a lot? mass quantities?

Petawatt laser? How many watts in a petawatt? I suppose the article implies lower capital costs but still, petawatt laser doesn't sound like it's that cheap to run. It still doesn't tell me how much a gram or microgram of positrons would cost to make.

originally posted by: stormbringer1701
that positron production technique should also work for anti-protons if you up the power involved.

Yes so lower capital costs does seem inferred but still, larger than petawatt? Doesn't sound cheap.

well it sounds impressive and it is but the way these dudes get a petawatt is to chirp the power for a very brief fraction of a second. like atto seconds or femto seconds. so while it is impressive it's not so impressive as one would assume. they have lasers now that can put more power into a tiny target than the sun drops on all of north america in a second(? not sure of the time period in the comparison from memory.)

now if you had a petawatt laser that could dwell on a target for a minute or so; that would be what people who tend to be awed by petawatt lasers would think of.