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Can matter be destroyed?

Re: Re: Re: Can matter be destroyed?

wollery said:
Matter, at least the matter we are made of, consists of atoms made of protons, neutrons and electrons. Antimatter consists of atoms made of particles with equal masses but opposite charges to matter. Interestingly, this means that there is no such thing as an anti-neutron.
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There is such a thing as an anti-neutron. It and the neutron simply have the same (zero) charge, but they differ in other properties, such as baryon number.
 
What happens if a proton and an anti-electron meet? Do they form a weird Hydrogen atom? Do parts of them anihilate, and you get some quarks left over? Do they not interact with one another at all?
 
Donks said:
What happens if a proton and an anti-electron meet? Do they form a weird Hydrogen atom? Do parts of them anihilate, and you get some quarks left over? Do they not interact with one another at all?
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Particles can only anihilate with their specific anti-particle, so no fireworks there.

Both the proton and anti-electron have a positive charge, they wouldn't be interested in being close together at all.

When particles and anti-particles meet, there are no parts left over, just a flash of (high energy) light.
 
Huntsman said:
Okay, now I have to ask for clarification.

I KNOW I've heard that bit about spin being opposite. Here, I found a link from Lawrence Radiation Laboratory about anit-matter with the following quote:
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Well, spin isn't actually a scalar quantity. When talking about a generic particle (as oposed to a specific particle in a specific state), it's generally just the magnitude that's important. Antiparticles have the same spin magnitude as particles.

As for magnetic moment, well, the magnetic moment is proportional to the spin, by a factor known as the gyromagnetic ratio. I'm not sure if gyromagnetic ratios for particles and antiparticles are opposite, but I'm fairly sure they can be negative, so it wouldn't surprise me terribly. Anyone know?
 
I remember reading that according to current estimates, gravitational force will not be able to overcome the universe's expansion. Therefore, ALL particles in the universe will ultimately decay in to a cold radiation background.

This could be added to the E=m*C^2 and matter-antimatter collisions as another way of "destroying" or "converting" matter.

This decayed universe does not fit with most religious beliefs, eh? Specially those that propose a sequence of cycles similar to big-bang-big-crunch repeated ad infinitum. Now, if one thinks of Ragnarok, theres a vague resemblance, for the cold will ultimatelyl win...
 
Correa Neto said:
I remember reading that according to current estimates, gravitational force will not be able to overcome the universe's expansion. Therefore, ALL particles in the universe will ultimately decay in to a cold radiation background.

This could be added to the E=m*C^2 and matter-antimatter collisions as another way of "destroying" or "converting" matter.

This decayed universe does not fit with most religious beliefs, eh? Specially those that propose a sequence of cycles similar to big-bang-big-crunch repeated ad infinitum. Now, if one thinks of Ragnarok, theres a vague resemblance, for the cold will ultimatelyl win...
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They won't "decay", all matter and energy will move further and further apart. Keep in mind that this is just our current most promising theory. We've had several in the past 50 years.

Steady State is even worse for the religious (since with the Big Bang they can point to a start and say "God did it"). If the universe is continually expanding and contracting with no matter/energy destroyed, that really leaves God out of the picture because there is no "creation".
 
DangerousBeliefs said:
They won't "decay", all matter and energy will move further and further apart. Keep in mind that this is just our current most promising theory. We've had several in the past 50 years.

Steady State is even worse for the religious (since with the Big Bang they can point to a start and say "God did it"). If the universe is continually expanding and contracting with no matter/energy destroyed, that really leaves God out of the picture because there is no "creation".
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Steady state was discredited precisely because it requires matter to be created at a constant rate to fill the gaps left by the expansion of the Universe (which was known about at the time). This obviously violates the conservation of matter/energy.
 
Some answers...

First of all, as has been pointed out, mass and energy are equivalent. To prohibit confusion, I will use energy, as it is the more general notion. The question then becomes can energy be destroyed.

The short answer is no. Energy is always transfered equivalently in any nuclear, chemical, or mechanical action. Thus the law of conservation of energy. Energy can be lost into a black hole, where its energy is turned into mass and gravitational energy, etc.

Now, when we get down to quantum-level physics, things get hairy (literally). In this realm, matter/antimatter pairs of particles can appear spontaneously, then cancel back out into energy. The problem is, around black holes, one half of the pair gets sucked in, and the other is released. This creates the problem, it seems to create energy from nothing! However, current theories predict that this interaction actually reduces energy in the black holes, and that black holes actually do radiate very, very slowly, eventually evaporating. (Does anyone know of any verifications of this theory?)

Thirdly, there is this 'zero-point energy' phenomenon. This results from Heisenberg's Uncertainty Principle stating we can know a fields strength or the change of strength over time (flux?), but not both accurately at the same time. Thus, a field can not be both 0 in strength and not changing. This means that all space/time seems to be a tempest of ghostly "fake" energy that is always changing. In this sense, energy is created and destroyed constantly. In fact, it is this phenomenon that creates the pair of particles above out of just this "foam" (this is the technical term... ;-).

The interesting thing is, the ZPE is the quantum equivalent of heat in thermodynamics. It cannot be harnessed or manipulated, and it seems so far that all attempts to circumvent the Universal "No Free Lunch" Theorem are thwarted by our pesky reality (see the paragraph on black holes... even when we think up ways to trick the universe, the universe tricks us back ;-).
 
DangerousBeliefs said:


They won't "decay", all matter and energy will move further and further apart. Keep in mind that this is just our current most promising theory. We've had several in the past 50 years.
...
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I remember quite well that the article described the decay of all particles, protons included, for example. Protons are supposed to have a half-life of 10^33 years- much more than he universe's current age. Sure, distances between galaxies will become quite bigger with time.

The sequence was something like this (I'm typing from memory, so, errors are quite likely to happen):

-increase in distance between galaxies;
-decrease in star formation rate up to the point where stellar "deaths" (supernova formation or sun-sized stars becoming white dwarves) are more numerous than formation of new stars;
-black holes "eat" what's left of gas and dust at their attraction range;
- decay of particles that compose matter becomes an important effect; this is supposed to happen in about 10^33 years from now, if estimates on baryon stability are OK, so, don't hold your breath;
- black holes "evaporate"

Of course, that's what is supposed to happen according to our current state of knoweledge, and I bet there are quite good researchers that do not agree with it.

Here's two links on baryon stability:
http://www-personal.umich.edu/~jcv/imb/imb.html
http://hep.bu.edu/~superk/pdk.html
 
Re: Some answers...

Gestahl said:
First of all, as has been pointed out, mass and energy are equivalent. To prohibit confusion, I will use energy, as it is the more general notion. The question then becomes can energy be destroyed.

The short answer is no. Energy is always transfered equivalently in any nuclear, chemical, or mechanical action. Thus the law of conservation of energy. Energy can be lost into a black hole, where its energy is turned into mass and gravitational energy, etc.

Now, when we get down to quantum-level physics, things get hairy (literally). In this realm, matter/antimatter pairs of particles can appear spontaneously, then cancel back out into energy. The problem is, around black holes, one half of the pair gets sucked in, and the other is released. This creates the problem, it seems to create energy from nothing! However, current theories predict that this interaction actually reduces energy in the black holes, and that black holes actually do radiate very, very slowly, eventually evaporating. (Does anyone know of any verifications of this theory?)
Click to expand...
Not literally, as in a laboratory, but that may change when the new accelerator at CERN comes online next year. If it does and this Hawking radiation is directly observed, expect Dr. Hawking to win the Nobel prize.

It has been confirmed indirectly by observations of presumed black holes in space, though.

Thirdly, there is this 'zero-point energy' phenomenon. This results from Heisenberg's Uncertainty Principle stating we can know a fields strength or the change of strength over time (flux?), but not both accurately at the same time. Thus, a field can not be both 0 in strength and not changing. This means that all space/time seems to be a tempest of ghostly "fake" energy that is always changing. In this sense, energy is created and destroyed constantly. In fact, it is this phenomenon that creates the pair of particles above out of just this "foam" (this is the technical term... ;-).

The interesting thing is, the ZPE is the quantum equivalent of heat in thermodynamics. It cannot be harnessed or manipulated, and it seems so far that all attempts to circumvent the Universal "No Free Lunch" Theorem are thwarted by our pesky reality (see the paragraph on black holes... even when we think up ways to trick the universe, the universe tricks us back ;-).
Click to expand...
Maybe, maybe not. One of its physical manifestations causes the Casimir Effect and that MAY lead to an actual exploitation of ZPE someday. Because there is a ZPE gradient between the outside and inside of a conductive cavity there is some room for real energy extraction.
 
Two Quarks and a Gluon were walking down the street and the Gluon sez "hey , how bout a threesome?" Well both the Quarks turned green at the prospect...
 
Correa Neto said:


I remember quite well that the article described the decay of all particles, protons included, for example. Protons are supposed to have a half-life of 10^33 years- much more than he universe's current age. Sure, distances between galaxies will become quite bigger with time.[/url]
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But particle decay releases energy and more particles (or sub-atomic particles)... so, nothing is destroyed.
 
I'm not a physicist by any stretch, but I have a question. If either a particle of matter or any form of energy crosses over the event horizon of a black hole, it can never return, right? Essentially, that matter or energy no longer exists in our universe except as a gravity well. Now, I realize that black holes theoretically evaporate through the loss of one half of the "virtual" pair of particles that form at the edge of the event horizon. Does the evaporation of the black hole release as much energy as was lost to the hole while it existed?
 
scotth said:
When particles and anti-particles meet, there are no parts left over, just a flash of (high energy) light.
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This is true for positron/electron annhiliations, but not for baryon/antibaryon annihilations.

When a proton and an antiproton meet, some of their mass is converted into gamma rays, but the rest turns into a slew of 5 or 6 mesons (pions, I believe). These mesons all have half-lives of less than a microsecond, so they transform themselved into gamma rays very quickly, but there is a tiny sliver of time during which these "parts left over" can be detected.
 
tracer said:

This is true for positron/electron annhiliations, but not for baryon/antibaryon annihilations.

When a proton and an antiproton meet, some of their mass is converted into gamma rays, but the rest turns into a slew of 5 or 6 mesons (pions, I believe). These mesons all have half-lives of less than a microsecond, so they transform themselved into gamma rays very quickly, but there is a tiny sliver of time during which these "parts left over" can be detected.
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It was my understanding that these weren't really parts left over, but were created from the energy of the initial destruction. But, I wouldn't be terribly surprised to be shown wrong at this level of detail.
 
DangerousBeliefs said:


But particle decay releases energy and more particles (or sub-atomic particles)... so, nothing is destroyed.
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Well, surely its a conversion.

Anyway, the final result will be a cold background radiation, the result of the decay of the baryons and the evaporation of the black holes. What will happen with this radiation? I have no idea...

Maybe Bad Astronomer could provide a cosmological hand here...
 
wollery said:
Steady state was discredited precisely because it requires matter to be created at a constant rate to fill the gaps left by the expansion of the Universe (which was known about at the time). This obviously violates the conservation of matter/energy.
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It has been my understanding that the death-knell of Steady-State theory was its failure to explain the cosmic microwave background radiation.
 
Skeptoid said:
It has been my understanding that the death-knell of Steady-State theory was its failure to explain the cosmic microwave background radiation.
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The CMB was a prediction made by Hawking from the Big Bang theory, although it's actual discovery was an accident. A number of people had previously objected to the steady state theory on the grounds that it required continuous mass creation, but the majority (and certainly the most vociferous people) preferred the aesthetic of steady state. To gain a foothold Big Bang had to produce an experimental verification, which came with the CMB. So, although it was the discovery of the CMB which ended the steady state stranglehold, it was already on its way out because of the mass/energy conservation problem.
How much people resisted the big bang idea can be seen from Einstein who, until Hubble discovered the expansion of the Universe, was adamant that the Universe should be static, and even added the cosmological constant to his equations to force this constraint on his models.
 
wollery said:
The CMB was a prediction made by Hawking from the Big Bang theory, although it's actual discovery was an accident.
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Surely it was before Hawking's time? I thought it was Alpher and Gamow who predicted the CMB.
 
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