Matter/Anti-Matter: Explaining Space Travel Applications

[DarkStar707]

Please explain the process of matter anti matter and how it could be used in space travel

 

[S.Vasojevic]

When matter and antimatter annihilate all the mass is converted to energy. This makes antimatter the most efficient fuel possible. Mass of the fuel is critical for space travel, so it also makes antimatter ideal fuel for space travel.

Just to give you some idea of numbers: you can match entire output of three space shuttle main engines during entire liftoff sequence with just 0.134 grams of antimatter - matter combination. Scary, isn't it?

 

[DarkStar707]

Well It's the kind of stuff That makes us a phase 2 society.
Are there current work in progress to make this happen?

 

[Matterwave]

They are creating anti-matter in labs, but the costs are prohibitive at this point. (~Several tens of trillions of dollars per gram)

Here's a paper on it:
http://www.engr.psu.edu/antimatter/Papers/NASA_anti.pdf

 

[DarkStar707]

Thanks for filling me in on this matter heh Pun completely intended

 

[Phyisab****]

As someone studying physics, it is very easy to get bogged down in the difficulties and mathematics and lose sight of the grand ideas which fascinated me as a child. Thanks for that link, I found it to be a very interesting examination of something at the intersection of physics and science fiction.

 

[Phyisab****]

Of course, storage of >~1g of antimatter in one place would present, I would have to assume, essentially insurmountable risks.

 

[DaveC426913]

Of course, storage of >~1g of antimatter in one place would present, I would have to assume, essentially insurmountable risks.

Puh-leeze. It can be stored in a cannister the size of a tennis ball can and contained with some dry cell batteries. I saw it in Angels & Demons.

 

[Phyisab****]

But I am assuming that But any failure would be so spectacular the entire device would have to be legally regulated

 

[jweie29nh]

I have questions about this too. Has anyone ever seen what antimatter looks like and what triggers antimatter to travel back in time? If antimatter does travel back in time then, where is the proof? Are there equations that explain how it goes back in time or has someone actually seen antimatter disappear in front of them to say that the antimatter opened a new dimension?

 

[DaveC426913]

I have questions about this too. Has anyone ever seen what antimatter looks like

It looks the same as matter. Photons are their own antiparticle, so when an antimatter atom emits a photon it gives no indication that it came from antimatter.

and what triggers antimatter to travel back in time?

It doesn't. where did you read this?

 

[Anti-Meson]

Firstly anti-matter does not exist in nature. Secondly when created, in lab, it takes more energy to create it than what can be yielded from it (thermodynamics). SO it is not viable means of powering anything.

 

[Phyisab****]

You are completely missing the point. It is useful as a storage mechanism.

 

[MotoH]

We need an anti-matter container to store this anti-matter. The container would explode if we touched it, so we need some anti-matter gloves. The gloves would explode if they touched our hands so we need anti-matter skin. We would then explode because we touched the earth, therefor we need an anti-matter earth.

Now how are we going to use anti-matter when anti-matter has become matter?

 

[Anti-Meson]

The answer is no because of the very fact that currently only a few atoms of anti-matter can be produced and that transporting such anti-matter is mind boggling. Any contact with normal baryonic matter and it will simply annihilate itself.

 

[DaveC426913]

What is going on here?

Firstly anti-matter does not exist in nature.

Of course it does.

Secondly when created, in lab, it takes more energy to create it than what can be yielded from it (thermodynamics). SO it is not viable means of powering anything.

Neither do Ni-CAD cells or Liquid Hydrogen, but they are an excellent way to power something.


As Phyisab**** points out, most of our propulsion systems are really storage devices. Producing the potential energy that is stored in this those batteries is always energy-intensive.

We need an anti-matter container to store this anti-matter.

All we need is a magnetic bottle.

 

[MotoH]

Thanks for ruining my whole theory Dave.

 

[Anti-Meson]

Of course it does.

Provide your evidence that anti-matter DOES exist in nature.

 

[DaveC426913]

Provide your evidence that anti-matter DOES exist in nature.

Feel free to start http://en.wikipedia.org/wiki/Antimatter#Origin_and_asymmetry".

Antiparticles are created everywhere in the universe where high-energy particle collisions take place. High-energy cosmic rays impacting Earth's atmosphere (or any other matter in the solar system) produce minute quantities of antimatter in the resulting particle jets, which are immediately annihilated by contact with nearby matter. It may similarly be produced in regions like the center of the Milky Way Galaxy and other galaxies, where very energetic celestial events occur (principally the interaction of relativistic jets with the interstellar medium). The presence of the resulting antimatter is detectable by the gamma rays produced when positrons annihilate with nearby matter. The gamma rays' frequency and wavelength indicate that each carries 511 keV of energy (i.e. the rest mass of an electron or positron multiplied by c2).

 

[Anti-Meson]

For Dave, may I point out this article produced by CERN - http://public.web.cern.ch/Public/en/Spotlight/SpotlightAandD-en.html

Admittedly, it is primarily focused on angels and demons but you will understand why anti-matter does not exist , exist being the key word, in nature.

There is no possibility to use antimatter as energy ‘source’. Unlike solar energy, coal or oil, antimatter does not occur in nature; we first have to make every single antiparticle, and we have to invest (much) more energy than we get back during annihilation.

EDIT: Dave, you are a PF contributor and supposed science advisor. I thought PF was a serious site promoting education. If you believe this you should stop referencing unregulated WIKIPEDIA and start referencing papers from scientific authority.

 

[Phyisab****]

EDIT: Dave, you are a PF contributor and supposed science advisor. I thought PF was a serious site promoting education. If you believe this you should stop referencing unregulated WIKIPEDIA and start referencing papers from scientific authority.

http://www.esa.int/esaCP/SEMKTX2MDAF_index_0.html

I followed the wikipedia citatation. The statement that antimatter does not exist is an enormous generalization. Of course it exists.

 

[DaveC426913]

For Dave, may I point out this article produced by CERN - http://public.web.cern.ch/Public/en/Spotlight/SpotlightAandD-en.html

Admittedly, it is primarily focused on angels and demons but you will understand why anti-matter does not exist , exist being the key word, in nature.




EDIT: Dave, you are a PF contributor and supposed science advisor. I thought PF was a serious site promoting education. If you believe this you should stop referencing unregulated WIKIPEDIA and start referencing papers from scientific authority.

I referenced Wiki for your benefit. It is a good place for you to start reading up on the subject if you're going to discuss it.

If someone comes on the board and says "F=ma is wrong", I'd do the same thing: "start here with your learning".

Your unilateral statement that it does not occur in nature is wrong. You can certainly modify it to say that it doesn't exist in great enough quantities and doesn't exist for long enough to be useful, but that would be a different claim.

For Dave, may I point out this article produced by CERN - http://public.web.cern.ch/Public/en/...tAandD-en.html

Admittedly, it is primarily focused on angels and demons but you will understand why anti-matter does not exist , exist being the key word, in nature.

Yes, an FAQ aimed at the uneducated who want simple answers about a film. Here at PF, it is not good enough to be so general.

 

[Anti-Meson]

http://www.esa.int/esaCP/SEMKTX2MDAF_index_0.html

I followed the wikipedia citatation. The statement that antimatter does not exist is an enormous generalization. Of course it exists.

Interesting, however, if you read the article it is not definitive if anti-matter exists in nature or not. There is some debate as to whether the detected 511 keV transmission spectra is caused by a positron-electron collision. Though thank-you for providing something not from wikipedia.

Other astronomers wondered whether more exotic processes were at work... so it was suggested that dark matter was annihilating or decaying into pairs of electrons and positrons, which then annihilated to produce the gamma rays.
The trouble with this idea, however, was that the dark matter particles needed to be much less massive than most theories were predicting.

 

[Phyisab****]

Please read that paragraph again. 511keV is the rest mass of an electron or positron. There is very little doubt the line is caused by electron positron annihilation.

 

[Anti-Meson]

You are misinterpreting that paragraph.

Elaborate if you wish to win me over.

 

[twofish-quant]

Anti-matter is something that people see all over the place. There's something near the center of the milky way that's creating lots of positrons. If you are trying to argue that antimatter doesn't exist in nature, that's more or less like trying to argue with someone that thinks the moon doesn't exist. If someone really insists that the moon does not really exist, it's hard to figure out where to begin to convince them otherwise. If you really, really want to argue that anti-matter does not exist in nature, most people in astrophysics will just think you are loony.

Also I think the wikipedia is a perfectly good source of information for general overviews of a topic. It has it's flaws, but the fact that anyone can edit strong encourages people with expertise on a topic to participate in a discussion. You can point to some of the flaws in wikipedia, but it's much, much better than any other source of information that I can think of.

 

[Phyisab****]

I really don't have any further argument. You are completely misinterpreting that paragraph. This thread "run its course" as they like to say here.

 

[twofish-quant]

Elaborate if you wish to win me over.

If you read the paragraph, you'll see that the open question is on what causes the positrons rather than that there are positrons. Anytime you have a 511 Kev spike, that's a positron annihilation line, there are no known physical processes that produce a 511 Kev spike other than anti-matter annihilation. You can go into http://adswww.harvard.edu/ for more details. (Search for pair production)

 

[Anti-Meson]

If you are trying to argue that antimatter doesn't exist in nature, that's more or less like trying to argue with someone that thinks the moon doesn't exist. If someone really insists that the moon does not really exist, it's hard to figure out where to begin to convince them otherwise. If you really, really want to argue that anti-matter does not exist in nature, most people in astrophysics will just think you are loony.

Please keep your fallacious arguments off PF.

 

[Phyisab****]

ugh i forgot to unsubcribe

 

[Anti-Meson]

If you read the paragraph, you'll see that the open question is on what causes the positrons rather than that there are positrons. Anytime you have a 511 Kev spike, that's a positron annihilation line, there are no known physical processes that produce a 511 Kev spike other than anti-matter annihilation. You can go into http://adswww.harvard.edu/ for more details. (Search for pair production)

I think the majority of people here is misinterpreting my position, in that case I shall clarify, if I haven't done so already.

I do not deny the whether of antimatter is real or not, laboratories have shown that anti-matter is real and pair production is such an experiment. What I do deny is that antimatter exists in nature. By exists I mean it can it exist without be unaffected, similar to baryonic matter. However, this is not the case since it will simple annihilate with any baryonic matter and the end result is either pure energy, in form photons or more baryonic matter - not antimatter.

 

[S.Vasojevic]

As Phyisab pointed, it is about how much energy you can 'carry' on a space ship, not about mining the antimatter from nature. With antimatter you will get engines with highest specific impulse possible. Problem of puting that energy to use remains, because it comes as gamma rays, but nevertheless concept seems plausible.

 

[DaveC426913]

I think the majority of people here is misinterpreting my position, in that case I shall clarify, if I haven't done so already.

I do not deny the whether of antimatter is real or not, laboratories have shown that anti-matter is real and pair production is such an experiment. What I do deny is that antimatter exists in nature.

No, your position is very clear and unambiguous. You are arguing that antimatter does not exist in nature. That's not true.

By exists I mean...

Trying to change the meaning of the words you used after-the-fact does not make your original argument any less wrong.

Rather than try to backpedal, just concede that you made a claim you should not have made. Nor is there any need to redirect what you meant to say, we've got that covered: anti-matter does not exist in nature in any large enough quantity or for any length of time to be of use in the way we've been discussing it here. This we can agree on.

 

[DaveC426913]

Point of order: the OP asked about antimatter travellnig backward in time. I said 'no' but the OP provided a link to some article about it. That link seems to have gone missing. Was it deleted? I never had a chance to read it.

 

[Phyisab****]

yep seems to have been deleted

 

[Redbelly98]

What I do deny is that antimatter exists in nature. By exists I mean it can it exist without be unaffected, similar to baryonic matter.

Here is a link to an article in a peer-reviewed journal, Nature, that discusses large quantities of non-manmade positrons:

http://www.nature.com/nature/journal/v451/n7175/full/nature06490.html

... our result implies that up to a few times 10⁴¹ positrons escape per second from a typical hard LMXB.

 

[qraal]

Point of order: the OP asked about antimatter travellnig backward in time. I said 'no' but the OP provided a link to some article about it. That link seems to have gone missing. Was it deleted? I never had a chance to read it.

In a Feynman vacuum diagram the antiparticle-particle pair has the regular matter going forward in time and the antiparticle going backwards. You can represent antimatter as time-reversed matter according to Feynman, but there's no way of verifying such time-reversal with tiny amounts of antimatter. Most interactions are time-symmetric!

 

[Frame Dragger]

How can you argue that anti-matter doesn't exist in nature? Did you just mean to say that matter dominates antimatter in the observed universe, or are you on drugs?

@graal: Hawking Radiation would confirm that mechanism, if it were to be observed in an earthbound analogue. (sonic - phonons)

 

[qraal]

How can you argue that anti-matter doesn't exist in nature? Did you just mean to say that matter dominates antimatter in the observed universe, or are you on drugs?

@graal: Hawking Radiation would confirm that mechanism, if it were to be observed in an earthbound analogue. (sonic - phonons)

What would an 'antimatter analogue phonon' look like? Freaky. Amazing that such a neat analogue can be found in superfluidics to Black Holes. The cross correspondances between such disparate areas of physics is truly a wonder!

 

[Anti-Meson]

No, your position is very clear and unambiguous. You are arguing that antimatter does not exist in nature. That's not true.

That is not my argument.

Trying to change the meaning of the words you used after-the-fact does not make your original argument any less wrong.

I am trying to explain to you what I mean by doesn't exist. I am not "changing the meaning of the words".

Here is a link to an article in a peer-reviewed journal, Nature, that discusses large quantities of non-manmade positrons:

http://www.nature.com/nature/journal/v451/n7175/full/nature06490.html

Very interesting indeed. Further investigation into the 511 keV signature is needed. Currently, I am not convinced. Let me point you to this article from APS:

http://prl.aps.org/abstract/PRL/v92/i10/e101301

The source of positrons in the galaxy is the subject of much debate...we argue that light DM particles (
1–100 MeV) annihilating into e^-e pairs in the galactic bulge may be the source of the observed 511 keV emission line

How can you argue that anti-matter doesn't exist in nature? Did you just mean to say that matter dominates antimatter in the observed universe, or are you on drugs?

This is sort of my argument but not entirely. I am not arguing that normal matter dominates antimatter in the observable universe, I am arguing that it does not exist on an appreciable time scale - it is simply annihilates. Putting it another way it does not coexist with normal matter.

 

[DaveC426913]

I am trying to explain to you what I mean by doesn't exist. I am not "changing the meaning of the words".

The time for you to say what you "really meant to say" was back when your original claim was shot down as patently false. Instead of demanding evidence to the contrary you could have just said "OK. Point made. Here's what I meant to say".

The rest of this goalpost-moving is for your personal benefit.

I am arguing that it does not exist on an appreciable time scale

Sure, now you are. Except it was left to me to make that correction.

Putting it another way it does not coexist with normal matter.

The thing about the vacuum of space is that things can get pretty far without encountering matter. In terms of particles with short lifespans, antimatter particles are comparatively immortal.


None of this is accomplishing anything anymore. The facts have been stated, the falsehoods falsified. Let's move on.

 

[Anti-Meson]

The time for you to say what you "really meant to say" was back when your original claim was shot down as patently false. Instead of demanding evidence to the contrary you could have just said "OK. Point made. Here's what I meant to say".

The rest of this goalpost-moving is for your personal benefit.

Sure, now you are. Except it was left to me to make that correction.

I do believe I had implicitly stated this from the start.

...any contact with normal baryonic matter and it will simply annihilate itself.

The thing about the vacuum of space is that things can get pretty far without encountering matter. In terms of particles with short lifespans, antimatter particles are comparatively immortal.

Space is far from vacuous. A plasma from solar winds permeate space meaning antimatter particles are far from immortal.

Let's move on.

Agree.

 

[twofish-quant]

One thing about anti-matter is that it is routinely used in medicine see...

http://en.wikipedia.org/wiki/Positron_emission_tomography

 

[Anti-Meson]

PET is excellent at exploiting the natural decaying of radionuclide isotopes. Although all of the isotopes are artificially created by means of bombardment.

 

[Vanadium 50]

Although all of the isotopes are artificially created by means of bombardment.

True, but that is a statement about medical practicality, not existence. I-131 is artificially created for medical treatments, but one would hardly use this to argue against the existence of iodine.

There are natural positron sources. The most common of them is probably the beta+ decay of potassium-40.

 

[Frame Dragger]

True, but that is a statement about medical practicality, not existence. I-131 is artificially created for medical treatments, but one would hardly use this to argue against the existence of iodine.

Anti-Meson might...


Look, there is a lot of effort going into saving one man's ego. If he hasn't learned to say, "Whoops, I was so wrong it hurts a little" as we ALL HAVE, then let him keep his misconceptions. This is no longer about informing someone either... in essence, this has become an intellectual curb-stomping. I'm really enjoying it, but I think it would be kinder to cut this individual loose at this point.

Lets all just pretend that Anti-Meson comes from a universe that lacks the Weak nuclear force, and therefore beta decay NEVER OCCURS! Ok?! I'll do it if everyone else will...

 

[Anti-Meson]

True, but that is a statement about medical practicality, not existence. I-131 is artificially created for medical treatments, but one would hardly use this to argue against the existence of iodine.

There are natural positron sources. The most common of them is probably the beta+ decay of potassium-40.

You do not understand my argument, I am not arguing against the existence of iodine. What I am arguing however is that antimatter simply does not exist, naturally on earth. PET nuclides are artificially created to induce antimatter - positrons. Potassium-40 is natural (0.0117% of all Potassium) but the fact that we know it undergoes positron emission is from theoretical models not physical observation. From our model of the big-bang heavy atoms (of which potassium-40 would be classified as) form at about 10⁸ years after the big-bang. Considering that Potassium-40 has a half life of 1.265 x 10⁹ years that means we will only be able to provide evidence to our model by observing a natural existing positron 10¹⁶ years after the big-bang. Approximately, ten million years from now.

Anti-Meson might...


Look, there is a lot of effort going into saving one man's ego. If he hasn't learned to say, "Whoops, I was so wrong it hurts a little" as we ALL HAVE, then let him keep his misconceptions. This is no longer about informing someone either... in essence, this has become an intellectual curb-stomping. I'm really enjoying it, but I think it would be kinder to cut this individual loose at this point.

Lets all just pretend that Anti-Meson comes from a universe that lacks the Weak nuclear force, and therefore beta decay NEVER OCCURS! Ok?! I'll do it if everyone else will...

This is not about my ego, I am making an argument by not appealing to emotion. Additionally, I do not believe that the weak nuclear does not exist (check my PF username- what does it say?), if it didn't I wouldn't be sat here writing this, none of this universe would exist.

 

[Astronuc]

Please let's keep the thread on topic - which is about explaning the process of matter anti matter and how it could be used in space travel.

Quite simply, anti-matter in useful quantities would have be produce by colliding accelerators (proton sychrotrons). However, the production rates are extremely inefficient, and currently the capacity is on the order of picograms per year, meaning it would take a trillion years to produce ~1g.

Anti-matter is theoretically ideal since it would reduce the propellant mass required for a long mission. Chemical propellant produce eVs per reaction, fission produces 200 MeV per fission, but less than 1 MeV/amu, and fusion produces a few MeVs per amu. Anti-matter anihilation produces 100's of MeV/amu.

Anti-matter would be released into a stream of hydrogen propellant where it would anihilate and heat the propellant - possibly to plasma temperatures which would require a magnetic confinement system. Otherwise, at lower temps, it is more or less a conventional hydrogen thermal rocket.

BUT - antimatter production is extremely inefficient, and it requires complex storage (one has to produce anti-protons and positrons with which to form anti-hydrogen. Adding anti-neutrons to the problem greatly enhances the complexity).

Conisder that controlled fusion has proven rather elusive over the past 6 decades.


Whether or not anti-matter exists in Nature is irrelevant. It certainly doesn't exist in useful quantities, and even if it did, it would be difficult to collect with something made of matter -even with a magnetic bottle or confinement/shielding field.

If the thread does not remain on topic, the thread will be locked.

 

[Redbelly98]

I'm no expert, but as I see it the problems with using antimatter for rocket propulsion are:

1. Our inability to produce antimatter in useful quantities.
2. Our inability to produce it efficiently.
3. Our inability to store it.

Is there anything else that's not really covered by these reasons?

 

[Frame Dragger]

Please let's keep the thread on topic - which is about explaning the process of matter anti matter and how it could be used in space travel.

Quite simply, anti-matter in useful quantities would have be produce by colliding accelerators (proton sychrotrons). However, the production rates are extremely inefficient, and currently the capacity is on the order of picograms per year, meaning it would take a trillion years to produce ~1g.

Anti-matter is theoretically ideal since it would reduce the propellant mass required for a long mission. Chemical propellant produce eVs per reaction, fission produces 200 MeV per fission, but less than 1 MeV/amu, and fusion produces a few MeVs per amu. Anti-matter anihilation produces 100's of MeV/amu.

Anti-matter would be released into a stream of hydrogen propellant where it would anihilate and heat the propellant - possibly to plasma temperatures which would require a magnetic confinement system. Otherwise, at lower temps, it is more or less a conventional hydrogen thermal rocket.

BUT - antimatter production is extremely inefficient, and it requires complex storage (one has to produce anti-protons and positrons with which to form anti-hydrogen. Adding anti-neutrons to the problem greatly enhances the complexity).

Conisder that controlled fusion has proven rather elusive over the past 6 decades.


Whether or not anti-matter exists in Nature is irrelevant. It certainly doesn't exist in useful quantities, and even if it did, it would be difficult to collect with something made of matter -even with a magnetic bottle or confinement/shielding field.

If the thread does not remain on topic, the thread will be locked.

Above all, every respectable study has shown that even with H->He Fusion (Edit for clarity: fusion as a power source for creating antimatter), the power required is prohibitive. The yield of antimatter is always in a pretty straight linear relationship with the power (electricity in this case) put into the process.

That said, while it's certainly unlikely that anti-matter exists in quantity in the observed universe, it's not a certainty. I personally don't believe it, but there have been arguments for 'patches' of antimatter isolated from matter, and while it annihilates immidiately there are reactions =/> energetic than any on Earth which presumabely create short-lived anti-matter.

As a drive-fuel, I can't think of anything worse. One thing Star Trek definitely appreciated was that the only 'fail safe' a matter-antimatter reactor can have on a spaceship, is to be violently ejected. ANY hint of containment failure for the antimatter, any leakage or loss of power, and BLAM, suddenly your whole ship is the other half of the fuel equation.

Finally, as a fuel, it doesn't produce 100% energy that is immediately useful, every time. Depending on the matter/antimatter, you could be losing up to 50% of the reaction to worthless (from our perspective) neutrinos! Of course, the most 'out there' reason would be that an antimatter drive would by definition be almost indistinguishable from a very powerful BOMB. For those victims of Differential Aging returning to a populate in their 'future' (I assume the antimatter rocket goes near c after all), or aliens encountering our intrepid vessel, might shoot first and ask questions later.

Oh... and landing and takeoff? WOW. Tensiooooooon!