Pure Energy ??

[geordief]

https://www.symmetrymagazine.org/article/lhcb-discovers-matter-antimatter-asymmetry-in-charm-quarks

 

"Matter and antimatter cannot coexist in the same physical space because if they come into contact, they annihilate each other. This equal-but-opposite nature of matter and antimatter poses a conundrum for cosmologists, who theorize that the same amount of matter and antimatter should have exploded into existence during the birth of our universe. But if that’s true, all of that matter and antimatter should have annihilated one another, leaving nothing but energy behind."

 

That quote from an article detailing recent findings  at the  Large Hadron Collider  (probably a more interesting story in itself than my query)

 

I thought  I had learned that "pure energy" is a misconception but that quote seems to me to be describing it in those terms.

 

The matter /antimatter  collision seems to leave behind nothing but energy. Can anyone clear up my misunderstanding?(I thought there was a respectableschool of thought that  posited that there was a zero total of energy in the universe even though perhaps this could never be shown experimentally)

[Sensei]

2 minutes ago, geordief said:

The matter /antimatter  collision seems to leave behind nothing but energy.

Annihilation of electron with positron yields (typically) two gamma photons:

[math]e^- + e^+ \rightarrow \gamma + \gamma + 1.022 MeV[/math]

Each gamma photon [math]\gamma[/math] has energy ~0.511 MeV = ~510998.928 eV

These photons interact with matter (or antimatter) and being absorbed, scattered etc. etc. and split to large bunch of lower energy photons, so at the end you deal with x-rays, UV photons, visible photons, IR photons, then MW photons, in multi-million (and later multi-billion) quantity. Photons carry energy released during annihilation (in the case of electron-positron annihilation, not true for other types of annihilation though).

 

[swansont]

22 minutes ago, geordief said:

 I thought  I had learned that "pure energy" is a misconception but that quote seems to me to be describing it in those terms.

Popular science writings will often take such shortcuts.

[studiot]

Not only do the phtons carry energy they also have momentum.

So, before you ask, no, photons are not 'pure energy' despite often being accused of this in the popular press.

[mathematic]

Energy is used to describe photons, etc. which have no rest mast.  Pure is a popular term which means there are no particles with mass, such as electrons, quarks, etc.  The fundamental question that is under discussion here is why is there matter now?

[Eise]

13 hours ago, geordief said:

But if that’s true, all of that matter and antimatter should have annihilated one another, leaving nothing but energy behind

At least in the news article at CERN itself this is not mentioned. 

[MigL]

Mass and energy are often confused with matter and radiation.
The former are simply properties of the latter.
The property of mass for leptons ( quarks/electrons )only 'emerged' after the Electroweak symmetry break.

( one wonders if energy is the 'fundamental' form of mass ? )

[studiot]

1 hour ago, MigL said:

Mass and energy are often confused with matter and radiation.
The former are simply properties of the latter.
The property of mass for leptons ( quarks/electrons )only 'emerged' after the Electroweak symmetry break.

( one wonders if energy is the 'fundamental' form of mass ? )

Well put Sir. +1

[Spaceman Spiff]

On 3/22/2019 at 7:34 AM, MigL said:

Mass and energy are often confused with matter and radiation.
The former are simply properties of the latter.
The property of mass for leptons ( quarks/electrons )only 'emerged' after the Electroweak symmetry break.

( one wonders if energy is the 'fundamental' form of mass ? )

So when we discuss E=mc², what we are really discussing is the conversion of a particular property of one thing into another property of a different thing?  So what about the conversion of the things (matter and radiation) themselves?  Although now that I think about it a little, the only way to know that a thing exists is to observe/measure a property of that thing.

So then - during an atomic fission event when a measured amount of mass disappears, and a measured amount of energy appears, does matter actually change into radiation, or are we just measuring 2 properties of the same thing?

[swansont]

17 minutes ago, Spaceman Spiff said:

So when we discuss E=mc², what we are really discussing is the conversion of a particular property of one thing into another property of a different thing?  So what about the conversion of the things (matter and radiation) themselves?  Although now that I think about it a little, the only way to know that a thing exists is to observe/measure a property of that thing.

So then - during an atomic fission event when a measured amount of mass disappears, and a measured amount of energy appears, does matter actually change into radiation, or are we just measuring 2 properties of the same thing?

Mass is a form of energy. When fission (or any exothermic reaction) occurs, mass is converted into other forms of energy. Primarily KE of the fission fragments, with some left over for KE of neutrons and photons. 

[beecee]

21 minutes ago, Spaceman Spiff said:

So then - during an atomic fission event when a measured amount of mass disappears, and a measured amount of energy appears, does matter actually change into radiation, or are we just measuring 2 properties of the same thing?

I'm pretty sure that in actual fact no mass disappears, rather it is simply the release of "binding energy" that holds the protons and neutrons together. The mass residue from nuclear fission is Barium and Krypton. I'm willing to be corrected on that score though.

Edited June 3, 2019 by beecee

[Spaceman Spiff]

2 hours ago, beecee said:

I'm pretty sure that in actual fact no mass disappears, rather it is simply the release of "binding energy" that holds the protons and neutrons together. The mass residue from nuclear fission is Barium and Krypton. I'm willing to be corrected on that score though.

I am sorry. Maybe "disappears" was the incorrect word to use. 

I am referring to the change in total mass defect (and therefore binding energy) that results from the fission equation  .  The binding energies are: U-235 = 1784 MeV; Ba-142 = 1180 MeV; Kr-91 = 778 MeV.  This results in 174 MeV excess energy released per nucleus of U-235. 

No I do not know the root cause of the resulting mass difference even though the numbers of protons & neutrons match, however the since both measured properties (mass defect & binding energy) equate using E=mc² for each atom, I am reasonably certain that there is an equivalent difference in the total mass defect between the 2 sides of the fission equation.

[Sensei]

3 hours ago, Spaceman Spiff said:

I am referring to the change in total mass defect (and therefore binding energy) that results from the fission equation  .  The binding energies are: U-235 = 1784 MeV; Ba-142 = 1180 MeV; Kr-91 = 778 MeV.  This results in 174 MeV excess energy released per nucleus of U-235.  

Nuclear binding energy that you mentioned ~1.7 .. 1.8 GeV is energy required to split nucleus of Uranium-235 to the all free protons and free neutrons.. In reaction that you gave, it's not happening.

Check lecture at my signature how Decay Energy should be calculated.

 

 

Take for example the simplest fusion reaction. From two protons, each with rest-mass 938.272 MeV/c^2, there is made Deuterium, and released is energy (particles with kinetic energy). Binding energy of Deuterium is 2.22 MeV. If you would like to disintegrate Deuterium atom to free proton and free neutron you would have to spend these 2.22 MeV energy (typically in form of kinetic energy of incoming accelerated particle).

How to get these 2.22 MeV?

( rest-mass of proton * c^2 + rest-mass of neutron * c^2 ) - rest-mass of deuterium nucleus * c^2 = 2.22 MeV

Notice one thing: at the beginning, prior initial fusion, we had 938.272 MeV * 2 = 1876.544 MeV i.e. less than sum of rest-masses of free proton and free neutron * c^2 together!

 

In the case of Uranium-235 to calculate binding energy there is used approximate general formula

Z * 938.272 MeV + N * 939.565 MeV - ( rest-mass of some isotope - Z * 0.511 MeV ) * c^2

 

 

Edited June 4, 2019 by Sensei

[beecee]

5 hours ago, Spaceman Spiff said:

I am sorry. Maybe "disappears" was the incorrect word to use. 

I am referring to the change in total mass defect (and therefore binding energy) that results from the fission equation  .  The binding energies are: U-235 = 1784 MeV; Ba-142 = 1180 MeV; Kr-91 = 778 MeV.  This results in 174 MeV excess energy released per nucleus of U-235. 

No I do not know the root cause of the resulting mass difference even though the numbers of protons & neutrons match, however the since both measured properties (mass defect & binding energy) equate using E=mc² for each atom, I am reasonably certain that there is an equivalent difference in the total mass defect between the 2 sides of the fission equation.

Perhaps also I should have referred to matter instead of mass, as I believe you are correct.

Induced fission reaction. A neutronis absorbed by a uranium-235 nucleus, turning it briefly into an excited uranium-236 nucleus, with the excitation energy provided by the kinetic energy of the neutron plus the forces that bind the neutron. The uranium-236, in turn, splits into fast-moving lighter elements (fission products) and releases a small amount of free neutrons. At the same time, one or more "prompt gamma rays" (not shown) are produced, as well.

from https://en.wikipedia.org/wiki/Nuclear_fission

Edited June 4, 2019 by beecee

[Spaceman Spiff]

7 hours ago, Sensei said:

Nuclear binding energy that you mentioned ~1.7 .. 1.8 GeV is energy required to split nucleus of Uranium-235 to the all free protons and free neutrons.. 

I agree with your definition of binding energy.  However, since fission induced by collision with a neutron is not the same as natural radioactive decay (alpha, beta, gamma), I stand by the arithmetic of the fission equation given (yes - the kinetic energy of the incoming neutron is being ignored).

I am new to SFN, but i feel that we are moving away from (hijacking?) the intended theme/subject of this topic.  It was last directly addressed (I think,) by MigL's intriguing post (quoted below).

On 3/22/2019 at 7:34 AM, MigL said:

Mass and energy are often confused with matter and radiation.
The former are simply properties of the latter.
The property of mass for leptons ( quarks/electrons )only 'emerged' after the Electroweak symmetry break.

( one wonders if energy is the 'fundamental' form of mass ? )

So the question I am submitting here for consideration is: 

Starting by positing E=mc², and that mass and energy are simply properties of matter and radiation;   Is E=mc² simply equating the measurement of a specific property (energy) of something to another property (mass) using a conversion factor (c²)?  If so, then I think that only works if both properties are of the same thing.

Therefore, maybe matter does not actually change into radiation, instead what we experience as matter and radiation are 2 different "manifestations" of the same thing?

[MigL]

Changing one property, changes a lot of others.

Taking away a particle's inertial mass constrains it to move at c and have no valid rest frame.
So I don't really see how you can call them different manifestations of the 'same thing'.

[Spaceman Spiff]

2 hours ago, MigL said:

Changing one property, changes a lot of others.

I agree.  But I was only considering measuring/observing the property not changing it.

2 hours ago, MigL said:

Taking away a particle's inertial mass constrains it to move at c and have no valid rest frame.

If E=mc² , and we make m=0, then E=0 also. 

No energy => no motion @ 0 Kelvin.

So the space-time (x, y, z, t) frame from which the observation is made would then be the rest frame.

2 hours ago, MigL said:

So I don't really see how you can call them different manifestations of the 'same thing'.

I have to think and research some more about my last question.  Maybe I said it wrong...

I know the concept I am trying to form, I need to figure out if it makes sense, and how to describe it.

Edited June 4, 2019 by Spaceman Spiff

[MigL]

The expression    E=mc^2  is not complete.
It only considers particles where  m  is the rest mass, and as such, doesn't apply to massless particles like photons.

[swansont]

6 hours ago, Spaceman Spiff said:

So the question I am submitting here for consideration is: 

Starting by positing E=mc², and that mass and energy are simply properties of matter and radiation;   Is E=mc² simply equating the measurement of a specific property (energy) of something to another property (mass) using a conversion factor (c²)?  If so, then I think that only works if both properties are of the same thing.

As I said earlier, mass is a form of energy. That’s one thing the equation means.

6 hours ago, Spaceman Spiff said:

Therefore, maybe matter does not actually change into radiation, instead what we experience as matter and radiation are 2 different "manifestations" of the same thing?

Radiation is the term for any particles produced in atomic and nuclear reactions. You can have neutron radiation, beta radiation (electrons and positrons), etc. Photons are electromagnetic radiation.

Matter and radiation are not different manifestations.

14 hours ago, Sensei said:

Nuclear binding energy that you mentioned ~1.7 .. 1.8 GeV is energy required to split nucleus of Uranium-235 to the all free protons and free neutrons.. In reaction that you gave, it's not happening.

That’s irrelevant. The energy released is still the change in binding energy.

2 hours ago, Spaceman Spiff said:

I agree.  But I was only considering measuring/observing the property not changing it.

If E=mc² , and we make m=0, then E=0 also.

As MigL has pointed out, the equation is incomplete. The original derivation was for a massive particle at rest, which limits the use of E = mc^2. 

The general form of the equation is E^2= p^2c^2 +m^2c^4