Anitmatter

[SilverTorch]

i read this article today, and it seems pretty cool.

from reading this section of anandtech, i knoe that there are alot of really bright people around here

with that said can anyone clearify the technology behind this.

thanks

 

[yomega]

I find it kinda funny how long it takes the main stream media to tell the public about "new technology"

I remember reading about antimater propulsion in Popular Science about 6+ months ago.

As for the technology behind it, I think you need to be more specific on what you want to know.

 

[bot2600]

I think the main thing holding it back is the difficulty making anti-protons.

Bot

 

[kulki]

very interesting article. But even if we have the power to travel across stars will we ever go faster than light is the real question?

 

[n18mets]

I also read an article in Popular Science Magazine quite a while back (more than 6 months). I think they said the main problem with antimatter was its high cost of production, and the dangers of storing it (I think it is stored in a magnetic field, but I am not sure). It will be quite a powerful form of propulsion when we have it under sufficient control in sufficient quantities. Hopefully, it will allow regular space exploration (if this does not happen by then [wishful thinking]).
I do not think the current space administration is equiped to handle something like that (NASA's budget should be increased). Anyway, these are just the opinions of a badly informed 17-year old high school student, so take them with a grain of salt.

 

[nirgis]

Antimatter is a long way off.... even small amounts could cause enough damage to the entire planet to vaporize it.

<I think they said the main problem with antimatter was its high cost of production, and the dangers of storing it (I think it is stored in a magnetic field, but I am not sure).>

Not only is it stored in a perfect magnetic field but also a perfect vacuum; any contact with matter, that is anything and the entire ship blows up.

An issue I am not certain is on the issue of acceleration; certainly the tremendous acceleration produced by an anitmatter-matter reaction would create quite a kickback. The magnetic field would have to be extremely calibrated to say the least.

My prediction: even if anti-matter is ever feasible, the inherent dangers are too great

 

[bsobel]

> I find it kinda funny how long it takes the main stream media to tell the public about "new technology"
> I remember reading about antimater propulsion in Popular Science about 6+ months ago.

Am I the only one who finds those two lines put together quite funny?
Bill

 

[rimshaker]

Try watching Star Trek: The Next Generation series. You'd be amazed at how much some of this technology is explained or mentioned in some educational form or content. The producers and writers obviously knew or read a great deal about very futuristic stuff.... i call it "semi-fiction"

 

[yomega]

By main-stream is CNN, MSNBC, FOX, etc...

the places where "normal" people get their info.

 

[Elledan]

If we're going to use anti-matter for space travel, the best way to travel would be not to move at all, i.e. warpdrive.

Another backdraw of a matter/anti-matter reaction is that during this reaction gamma radiation is produced. As you might know, this type of radiation is very hard to stop. Thick plates of lead do nothing.

 

[Evadman]

Water can help with gamma radiation can it not? Something like 8" of water will stop 80% of gamma radiation if I remember correctly. ( don't quote me on that, I remember it from a Scientific Amerian )

 

[AndyCunningham]

Antimatter isn't really a 'technology' at all yet, more just a theory. It can be produced in small amounts by very expensive equipment, and could also be theoretically loaded onboard a spaceship which would theoretically use the energy for propulsion.

The energy comes from the mass to energy conversion, in accordance with the old E=mc2 (sorry couldn't work out the superscript), which happens when matter and antimatter collide. As far as I know, most of the energy would be produced in the form of gamma radiation, I'm not convinced by the line "When a matter particle comes into contact with an antimatter particle, they annihilate each other and produce kinetic energy." It sounds simply untrue. Kinetic energy would mean a particle with mass is given a velocity, and radiation, carried by photons is massless. Either way all the problems with channelling the energy created into moving the ship in a specific direction aren't resolved yet.

However, it still doesn't really get around the problem that travel to other star systems would not proceed faster than light speed - in other words the round trip to the nearest star system would be over 8 years even with perfect antimatter propulsion. Finding a way around this barrier is really the ultimate problem for space travel, rather than any amount of perfection of a standard propulsion model. For travel about the solar system, it might one day be a reality, but I think that manned travel to other star systems will have to rely on a completely new transportation system.

 

[Elledan]

Here's some interesting information regarding the produced energy and the reaction products: http://www.physlink.com/Education/AskExperts/ae159.cfm

And for the Trekkies under us, a diagram of the PDS of the Enterprise: http://www.geocities.com/CapeCanaveral/Lab/9409/UFP/ncc1701e/plasma.html

 

[Shalmanese]

<< One pound is equal to 454 grams. >>



sigh, something tells me this is cut n pasted from a science article and then dressed up for public consumption .

And also, it is technically correct to say that it fors kinetic energy since, although photons are massless, they have a momentum and thus, a kinetic energy. It is misleading however because it gives the photons kinetic energy, not the ship.

The whole thing about them being able to reach mars in 2 weeks startled me though, doing some back-of-the-envelope calculations, that means thay will have an average acceleration of at least 738 m/s

Maybe my numbers are wrong though

Distance from sun to earth = 150,000,000 km
Distance from sun to mars = 225,000,000 km

Anybody else get the same figures assuming constant acceleration deaccleleration and going the shortest route?

 

[AndyCunningham]

Forgot about momentum, of course kinetic energy can be obtained from the collision.

But just working out your acceleration, I think you've gone wrong somewhere. At that acceleration, after around 10000 seconds you'd be travelling at around 7500 km/s, and have travelled half the distance. Assuming deceleration at the same speed the journey would only take about 5.5 hours. Still I'm pretty sure my own calculations are wrong somewhere - I keep getting that an acceleration of only 0.2 m/s would do it.

 

[CTho9305]

Here's an interesting problem.... if any of you read the "negative energy" article in SciAm (I think), you'll know that even in a perfect vacuum, energy fluctuates, sometimes slightly positive, sometimes slightly negative. if you hit antimatter with that positive energy, does it blow your ship up again, or are you OK because only matter causes destruction?

 

[Shalmanese]

There is no such thing as an antiphoton so energy fluctuations wouldnt affect it.

 

[J.Zorg]

Besides all other problems you have when you are dealing with antimatter, you just need to much ernergy to produce it.
I heard simple example for this from an Astrophysics professor:
If you would like to light a 40W light bulb with antimatter you would need at least 10 nuclear powerplants to produces the energy for creating the antimatter. The power of 10 nuclear powerplant would be something like 15TW = 15*10^12. You can easily calculate how effective this is.
Since you cant fly to the mars with 40W you would need a few more powerplants..... ;-)

Right now this is pure science fiction..

 

[Z_Amon]

A thorough grounding in hard science fiction comes in handy. ;-)

Typically, thoughts of largescale production of antimatter hinge in some cheap, easily available form of energy. Often, this is solar or fusion energy in proposals, with solar being the only really feasible non-nuclear form that we have available.

The next problem is where to generate the antimatter and how to store it safely in quantity. Both questions would be answered if the moon or another satellite was used as a generation location: safety due to distance and large areas for solar arrrays to generate the power.

Matter/antimatter reactions of a smaller size would require some form of shielding, but a constant thrust situation would not create the massive impact/explosion that you might think of from a largescale matter/antimatter reaction. Think on the individual atom or proton level rather than on the "we toss a gram of antimatter out and WHAM!" level.

Antimatter makes a lot of sense as a form of stored energy if you need a highly concentrated form - I look forward to the day that we manage to use it successfully (although, honestly, fusion would be more practical on a daily basis!)

Anybody know where I can pick up a nice ramscoop generation ship cheap? I need to replace my Buick...

Z.

 

[nirgis]

About this acceleration thing, one must also decelerate before reachibg the target, which would take a lot of additional time and fuel. I tend to not read yahoo science sections because I find them uniformed, doctored to be sensational, and most of the time wrong

 

[SilverTorch]

wow didn't think i was going to get that many replies, but anything and everything is welcome

i have understood everything that the article and you guys (and girls?) have thrown in for me to read.

besides the making and the storing of this stuff, how would the "engine" of the ship control and/or direct this highly energetic reaction. like jet engines on fighter planes, the opening becomes wide or narrow to allow the focus of thrust (this is probabily very simple and/or explanation), but how would the ship do that?

 

[SsZERO]

If I was going to build a spacecraft that uses matter-antimatter reactions for power, then the following are some things I'd definitely consider in my design.

Rather than storing antimatter, I believe it'd be more practical to store something which can be used to generate antimatter on the fly, as it is required. Not only would this be safer, but it would also be easier to control the rate of the reaction.

I am fairly certain that generating useful quantities of antimatter can be using a cascade reaction type. It would require a larger surge of energy to start the initial cycle, but once it gets going, the matter-antimatter reaction would sustain itself, cumulatively increasing energy output based on the flow of the material being used as fuel to create antimatter.

With the above in mind, the spacecraft would need secondary power supplies...such as nuclear reactors or something of that sort.

-= SsZERO =-

 

[Degenerate]

I read from a book that it was talking about harvesting some mass and the super compressing it to form a super dense object. Based on the priciple by Van. .someone (help me with the name) which says that energ fluctuates, and the smaller and heavier the object, the more fluctuation it has. So by producing a super dense, they could use this fluctuation to do something.

In the book it starts with coliding two particle at near light speed and then using a magnetic field to compress it futher.

 

[AndyCunningham]

I think you're (SsZero) confused a bit about the nature of the reaction. The reason that a fusion reaction needs energy to get going is because actually fusing the nuclei of two atoms together requires an enormous force to push them together against the electromagnetic force, since they have to pushed very close for the strong force to become the dominant one. Once in this state, it is a lower energy state, so therefore overall energy is released. This energy can be used to force two more nuclei together and continue the reaction - effectively the very large energy barrier stops the reaction happening at room temperature.

With anti-matter / matter I don't think there is such a large energy barrier. Because an antimatter particle has the opposite electric charge, the two particles attract rather than having to be forced together.

However, one thing to note is that producing an anti-matter particle, currently, is achieved by giving a lot of energy (kinetic) to a particle and colliding it with others. The antimatter (and matter) particles are created out of the pure energy. Then the matter-antimatter collision produces this same amount of energy.

As a power source onboard a ship, antimatter doesn't make much sense, since as much energy is needed for the creation as is released in the collision. With fusion for example, the products of the reaction are more stable (lower energy) than the reactants, so overall energy is released. This isn't true of an antimatter reaction. However, due to the 100% mass-energy conversion, a lot of energy can be stored in a compact space. For instance, if 500g of antimatter was produced, according to E=mc2 then 9*10^16 joules of energy from the conversion of 1kg of mass was converted to energy.

In line with conversation of momentum, to give the ship momentum, you would need to throw stuff out of the back of the ship. This is what rocket engines do - expansion of gas gives a momentum to exhaust fumes in one direction and therefore the ship gains momentum in the opposite direction. If you could somehow use the energy to fire particles out of the ship at near light speed then the ship would gain momentum in the opposite direction.

 

[joohang]

Hmm.. the article discusses it as though it's a new idea, but this idea has been around for quite a long time.

IIRC, even StarTrek or Star Wars has been selling this idea for a while too.