Is antimatter a theory or does it exist?

In summary, according to the author, matter and antimatter are made of the same stuff, but they are in different configurations. This allows for matter/antimatter collisions to occur with little to no need for force.
  • #1
azzkika
60
0
Is antimatter a theory or does it exist??

Does antimatter really exist?? if so, what is it made of, if not matter?? and is it subject to the same laws as normal matter?? i personally can't see how it is possible. in another thread i read that in a void where there is nothing it is possible for matter to emerge from nothing as long as an equal amount of antimatter emerges.

i know this is a theory, but has it ever been observed??

i personally think the mass and energy of the universe is unchangeable, but as ever there are differing opinions on this. for it to be unchangeable the antimatter theory must be incorrect as antimatter if it did exist could be composed of antimass, as anything that exists requires mass no matter how small. even light has mass, just a very very very small mass per photon.
 
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  • #2


Er... antimatter a "theory"? What do you think they have been colliding at the Tevatron all these years? Or even at LEP before it went away? And guess what the "P" in PET scan means that is now used in many medical procedure?

Zz.
 
  • #3


We define anti-matter as particles that have opposite charge to the particles (proton & electron) that constitute the matter (atoms) of which we and our environment is composed.

See - http://hyperphysics.phy-astr.gsu.edu/hbase/particles/antimatter.html

The positron (positively charged electron) is the anti-particle of the electron, and the anti-proton (negatively charged proton) is the anti-particle of the proton.

See also this - http://hyperphysics.phy-astr.gsu.edu/hbase/astro/cosmic.html
 
  • #4


I like your thinking. Matter and antimatter are made of the same stuff. It's just that they are in different configurations. Giving antimatter the opposite charge of what we consider to be matter.

Its this charge difference that allows matter/antimatter collisions to occur with little to no need for force(like trying to fuse protons).
 
  • #5


azzkika said:
Does antimatter really exist??
Of course it does. You are mistakenly thinking that antimatter means negative mass. An anti-electron (aka a positron, the P in PET) has the same mass but exactly the opposite charge as an electron. The same goes for anti-protons: same mass but opposite charge as a proton.

i personally think the mass and energy of the universe is unchangeable, but as ever there are differing opinions on this.
You are entitled to your own opinions, but not your own facts. The fact is that mass and energy are interchangeable. The US used this fact to its advantage to end World War II against Japan. Were this fact not true, the Sun couldn't shine. The photons in the sunlight are mass converted to energy in the center of the Sun by means of nuclear fusion.

even light has mass, just a very very very small mass per photon.
No, it doesn't. Photons are massless.
 
  • #6


One point that has not been made. Charge is not the only factor in matter antimatter difference. Neutrons have anti-neutrons, although both are uncharged.
 
  • #7


I did leave out neutrals, which also have their anti-matter partners.

Perhaps this will help - http://www2.slac.stanford.edu/vvc/theory/hadrons.html

The baryons have (qqq), where q is a quark (u, d, s), while their anti-particles are ([itex]\bar{q}\bar{q}\bar{q}[/itex]).

http://www2.slac.stanford.edu/vvc/theory/antiquarks.html

The term matter is then extended, by convention, to include:
  • All quarks, (charges +2/3 and -1/3).
  • All negatively charged leptons.
  • Left handed neutrinos.

Antimatter is, then, any particle built from:
  • Antiquarks (charges of -2/3 or +1/3).
  • Positively charged leptons.
  • Right-handed neutrinos.
 
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  • #8


D H said:
No, it doesn't. Photons are massless.
Photons as defined by QED. Otherwise, you can not rule out an unobservably small photon mass. This is actually very convenient, because you can make your calculations with a tiny photon mass, forgetting about gauge invariance, and set the photon mass to zero at the end of the day will not spoil your result.

mathman said:
Charge is not the only factor in matter antimatter difference. Neutrons have anti-neutrons, although both are uncharged.
Exchange all quantum numbers in general should do the trick. Electric charge, color charge, weak charge, helicity...
 
  • #9


mathman said:
Charge is not the only factor in matter antimatter difference. Neutrons have anti-neutrons, although both are uncharged.

That's not a good example, because neutrons are composed of quarks, which are individually charged, with the total charge being zero. An antineutron is composed of the corresponding antiquarks, which each have the opposite charge to their respective quarks, with the total still being zero.

A better example would be the neutrinos, which are fundamental particles as far as we know, and which have antiparticles.
 
  • #10


i asked the question because i read somewhere that anti matter explodes upon coming into contact with normal matter therefore we don't have any. obviously i am wrong. thanks for informing me. lol

and i cannot believe photons are massless as they exist. i believe they are just so light as to be almost unmeasurable and when coming into contact with other mass an equal weight is dispersed by reflection / refraction etc. hence all things don't lose or gain mass from light.this is only as i can't believe a thing can have zero mass and exist, (apart from a void or a vacuum i suppose).
 
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  • #11


azzkika said:
i asked the question because i read somewhere that anti matter explodes upon coming into contact with normal matter therefore we don't have any. obviously i am wrong. thanks for informing me. lol

If you are wrong then so is the Star Trek propulsion system. hehehe
 
  • #12


azzkika said:
and i cannot believe photons are massless as they exist. i believe they are just so light as to be almost unmeasurable and when coming into contact with other mass an equal weight is dispersed by reflection / refraction etc. hence all things don't lose or gain mass from light.this is only as i can't believe a thing can have zero mass and exist, (apart from a void or a vacuum i suppose).

Luckily, physics is typically verified not simply based on beliefs, but experiment. Till you can show an experimental evidence that photons have a non-zero, detectable mass, then your belief has no foundation.

And a photon isn't a "thing", the same way "kinetic energy" isn't a thing.

Zz.
 
  • #13


And a photon isn't a "thing",

When I Google 'is a photon a thing' , I get sent right back to here. https://www.physicsforums.com/showthread.php?p=1749537

Lightarrow says: (post #45)
"The subatomic particle that carries the electromagnetic force and is the quantum of electromagnetic radiation. The photon has a rest mass of zero, but has measurable momentum, exhibits deflection by a gravitational field, and can exert a force. It has no electric charge, has an indefinitely long lifetime, and is its own antiparticle."

Sounds like a 'thing' to me. If not, in gravitational lensing, What is getting lensed?
 
  • #14


azzkika said:
i asked the question because i read somewhere that anti matter explodes upon coming into contact with normal matter therefore we don't have any. obviously i am wrong. thanks for informing me. lol
Antimatter and matter do annihilate one another upon coming into contact, and that is exactly why we don't have (much) antimatter around us. That is also exactly how positron emission tomography works. Carbon-11, nitrogen-13, oxygen-15, and fluorine-18 decay via positron emission into other kinds of nuclei. For example, carbon-11 decays into boron-11 with a half-life of about 20 minutes. The positrons emitted from the decay don't live very long. As soon as they meet up with electrons the positrons and electrons annihilate one another. The PET scanner detects the gamma rays that result from this annihilation.
 
  • #15


azzkika said:
i asked the question because i read somewhere that anti matter explodes upon coming into contact with normal matter therefore we don't have any.

Statements like this give me that same, terrible feeling as you get when you scratch your nails against a chalkboard! It's not azzkika's fault, or anyone's fault I suppose, but it's sad that this kind of logic pushes into the public forum, and leads people to spectacularly false conclusions.

The problem, azzkika, is scale! If you take an electron and a positron (antielectron) and throw them together (slowly so kinetic energy is irrelevant), then out would come two photons, with a total energy of 500 keV (500,000 electron-volts). 1 eV is about [itex]10^{-19}[/itex] Joules, where 1 Joule is (roughly) the energy of a 1kg weight moving at 1 m/s. As you can see, this hardly qualifies as an "explosion!"

However, let's say you're not talking about a SINGLE electron or positron, but let's say you have a CHUNK of matter and antimatter, like a gram or more. There are something like $10^{27}$ electrons in a gram, so when you multiply it out, it suddenly becomes quite a LARGE explosion!

But you see, there are no antimatter chunks around here! So this kinda thing just doesn't happen. And it would be near impossible to make a chunk of antimatter that large, just because it wouldn't be stable in our matter-dominated universe! That is, it would fall apart before it ever got that big.

Antimatter explosions are PURE science fiction!

This issue of scale is very important in physics! This same kind of logic leads people to protest outside our national labs because we're going to make "black holes that will swallow up the universe!" Er...

NO!
 
  • #16


Thank you blechman.

I know your reply was to azzkika, but I want to thank you for the answer anyway.
Clear and understandable to people like me with far more curiosity than knowledge.

I grew up on Sci-Fi and have seen so many of the 'impossible' things become reality that it blurs the distinction between what is, and what can or cannot be.

Antimatter explosions are PURE science fiction!
Even during the emergence of the 'big bang' ? I was sort of under the impression that such energy was in part an explanation for the expansion phase ( inflation ? ) and the subsequent universe we have today.
Or is that just more Science fiction?



Originally Posted by azzkika
i asked the question because i read somewhere that anti matter explodes upon coming into contact with normal matter therefore we don't have any.
That statement sounds simple and correct also.




( don't go into detail please. I don't want to hijack the thread topic. ) Just curious.
 
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  • #17


Alfi said:
I grew up on Sci-Fi and have seen so many of the 'impossible' things become reality that it blurs the distinction between what is, and what can or cannot be.

The issue is what you mean exactly by 'impossible'! I would claim that creating a macroscopic nugget of antimatter is quite impossible by today's standards, strictly from an engineering standpoint, and that it's certainly not what's happening at particle detectors (which I know is not what you suggest, but I just want to clear that up).

Even during the emergence of the 'big bang' ? I was sort of under the impression that such energy was in part an explanation for the expansion phase ( inflation ? ) and the subsequent universe we have today.
Or is that just more Science fiction?

without going into details at all (there are a few issues with this statement you made, but I don't want to get into that here): I should have been more careful and say that such things are impossible TODAY (when the universe has cooled off considerably since the inflation epoch.
That statement sounds simple and correct also.

Referring to azzkika's statement: I take issue with the colloquial use of the word explosion - one thinks of an atom bomb going off! Not the case in any practical sense. People hear the word "matter" and "antimatter" in the same sentence and they think: "OH G-D, the universe is going to explode!" This is the myth I was trying to debunk. Just because one matter particle meets one antimatter particle in a bar, doesn't mean the big bang is going to repeat itself!
( don't go into detail please. I don't want to hijack the thread topic. ) Just curious.

details avoided as much as possible.

I'm sorry to sound so jaded (I'm trying very hard not to sound offensive), it's just that it is very important to keep this notion of size and scale in mind when talking about these things - I have had sooo many people come to me asking about super-explosions at Fermilab since there is "matter-antimatter collisions" there, it's just hard not to have my blood pressure go up! It's not that it's anyone's fault, it's just that the general public isn't correctly informed about what's really going on. I hope this little rant, as silly as it might be, helps people to see my point.

ADDED: I also don't mean to "hijack the thread" - I"m sorry if that's what I ended up doing.
 
  • #18


I have had sooo many people come to me asking about super-explosions at Fermilab since there is "matter-antimatter collisions" there, it's just hard not to have my blood pressure go up! It's not that it's anyone's fault, it's just that the general public isn't correctly informed about what's really going on. I hope this little rant, as silly as it might be, helps people to see my point.

Consider me as one of the 'general public' and again, I thank you for helping us update our views.

I understand your point. Please don't implode our planet. hehehe Arrrrrgggg ! Ya I see the frustration.
Keep the blood pressure in check, and persevere. We need you.
 
  • #19


Alfi said:
When I Google 'is a photon a thing' , I get sent right back to here. https://www.physicsforums.com/showthread.php?p=1749537

Lightarrow says: (post #45)
"The subatomic particle that carries the electromagnetic force and is the quantum of electromagnetic radiation. The photon has a rest mass of zero, but has measurable momentum, exhibits deflection by a gravitational field, and can exert a force. It has no electric charge, has an indefinitely long lifetime, and is its own antiparticle."

Sounds like a 'thing' to me. If not, in gravitational lensing, What is getting lensed?

It depends on what you mean by a "thing". Would the OP consider this as a thing as well? After all, he/she found it difficult for a "thing" to have no mass. Do you also consider "kinetic energy" to be a thing? After all, it has "energy", can do work, and in many cases, can be measured. Is this consistent with what you call a "thing" like the pen on your desk?

Zz.
 
  • #20


Do you also consider "kinetic energy" to be a thing?

No, Because the statement is not complete to me. The kinetic energy... of this thing, is the complete statement.

If we can detect a single (thing) proton. It becomes a thing to me with all the attributes of a thing for that reason. One of the attributes to the thing may be Kinetic energy, but the attribute is not the thing in itself.

Does kinetic energy get lensed in a gravity field?
 
  • #21


humanino said:
Photons as defined by QED. Otherwise, you can not rule out an unobservably small photon mass. This is actually very convenient, because you can make your calculations with a tiny photon mass, forgetting about gauge invariance, and set the photon mass to zero at the end of the day will not spoil your result.

Exchange all quantum numbers in general should do the trick. Electric charge, color charge, weak charge, helicity...

I thought the fact that gravity is the attraction of matter to matter and the fact light is affected by gravity indicates mass for attraction to take effect.
 
  • #23


Sorry if I offended anybody,
If I'm not banned I'd like to thank Joel for the great talk he gave at Black Pine school here in Berkeley.

Anti Hydrogen is his specialty. Anti Protons are only available at Cern and only in season so look for more great work on this as it comes in.
 
  • #24


Two and a half years ago...
 
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  • #25


and counting. Some things never change. Recent article in Nature is a paper by the author.
See
ALPHA at Cern
 
  • #26


But how does that make sence? If you have a group of identical atoms and then a group of antimatter that has an equaly negative mass then should't they disable each other instead of exploding?
 
  • #27


Antymattar said:
But how does that make sence? If you have a group of identical atoms and then a group of antimatter that has an equaly negative mass then should't they disable each other instead of exploding?

I could be wrong about this but I don't think negative mass is allowed. In any case the Charge, parity and time constraints ought to be satisfied. Your question seems to be whether there will be energy released in an anihilation event. Without answering I say that is a good question. Further,if energy is released and matter disappeared, then is it all electromagnetic, part kinetic with a little gravity thrown in or what?
 
  • #28


Antymattar said:
But how does that make sence? If you have a group of identical atoms and then a group of antimatter that has an equaly negative mass then should't they disable each other instead of exploding?

Antimatter doesn't have a negative mass. They have the same mass as their corrosponding particles. They have an opposite charge though.
 
  • #29


Astronuc said:
I did leave out neutrals, which also have their anti-matter partners.
...

Yes, you have to invert all matter quantum numbers to change from a particle to its anti-particle. In addition to the already mentioned electric charge, there are things like lepton number and baryon number.
 
  • #30


So anti matter isn't really anti matter at all. It is matter with opposite charge. Still matter in my view. I wish science would not have such ambiguous misleading terms such as this.
 
  • #31


Wow, first posted in 2008 and still going strong!
For what it's worth I found Feynman's lecture at the 1986 Dirac Memorial Lectures to be a good read on the subject, and explains nicely why there must be anti-particles.

Cheers
 
  • #32


Antymattar said:
a group of antimatter that has an equaly negative mass
Antimatter and negative mass are not the same thing.
Antimatter has positive mass.

azzkika said:
So anti matter isn't really anti matter at all.
No, antimatter is antimatter. :wink:

azzkika said:
I wish science would not have such ambiguous misleading terms such as this.
Huh? It isn't misleading or ambiguous. It has the opposite charge that matter has, that's why its called antimatter.
 
  • #33


FtlIsAwesome said:
Antimatter and negative mass are not the same thing.
Antimatter has positive mass.


No, antimatter is antimatter. :wink:


Huh? It isn't misleading or ambiguous. It has the opposite charge that matter has, that's why its called antimatter.

Heh, I can see how its misleading. If you instead described matter as having 2 parts, and labeled them as matter A and matter B (corresponding to matter and antimatter respectively) I think less people would be confused. But it's not a big deal. Once you get into science at all you learn the differences.
 

1. Is antimatter just a theory or does it actually exist?

Antimatter is not just a theory, it has been proven to exist through various experiments and observations in particle physics.

2. How is antimatter different from regular matter?

Antimatter is essentially the opposite of regular matter, with opposite charge and spin. When antimatter and regular matter come into contact, they annihilate each other and release a large amount of energy.

3. Can antimatter be created or destroyed?

Antimatter can be created through high-energy collisions, and it can also be destroyed when it comes into contact with regular matter. However, it cannot be created or destroyed in isolation, as it always needs to be paired with regular matter.

4. What are the practical applications of antimatter?

Antimatter has many potential applications, particularly in medical imaging and cancer treatment. It is also used in particle accelerators to study the fundamental building blocks of the universe.

5. Is it possible for antimatter to exist in large quantities in the universe?

While antimatter is rare in the universe, it is believed to exist in small quantities in certain cosmic events such as gamma-ray bursts. However, it is difficult to store and contain antimatter in large quantities due to its explosive nature when it comes into contact with regular matter.

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