Commander Posted June 11, 2017 Posted June 11, 2017 This OP is a Simple Question but I request the Scientists to bear with me to express some additional views while I await their answers. If the Universe had started at a particular instance and neutrons are such particles which can not be destroyed or created all of them should have the same age. By age if a reference point in time is indicated what is that ? Also what has caused the current dispersal and distances between all these neutrons ? If not and if so all these neutrons had always existed then too if they are neither created nor destroyed all must have the same Time of Existence !
Strange Posted June 11, 2017 Posted June 11, 2017 Most neutrons are in the hydrogen and helium formed about 13.8 billion years ago, when the universe cooled enough for nucleosynthesis to happen. That is about 99.5% of the matter in the universe, and most of that has remained unchanged since. But neutrons decay and are formed in all sorts of nuclear reactions (e.g. in stellar fusion) so there will be many younger neutrons as well.
Country Boy Posted June 11, 2017 Posted June 11, 2017 Your assumption "neutrons are such particles which can not be destroyed or created" is, as Strange said, incorrect. Neutrons can be both created and destroyed.
Commander Posted June 11, 2017 Author Posted June 11, 2017 Your assumption "neutrons are such particles which can not be destroyed or created" is, as Strange said, incorrect. Neutrons can be both created and destroyed. Yes, I had the Impression that Neutrons are such fundamental Particles that are not newly created or destroyed except in the formative processes when the Matter itself was created. The OP was based on this. In the nuclear processes I thought that Neutrons which were part of Heavier Elements were released and not newly created. We use methods to date ages of fossils by Carbon based methods but can we ever determine the age of a particular Particle or for that matter a Molecule of water I drink now as to when was it created ? I suppose not !
Strange Posted June 11, 2017 Posted June 11, 2017 Neutrons are unstable and free neutrons decay quite quickly. They are not fundamental particles, they are composed of quarks.
Commander Posted June 11, 2017 Author Posted June 11, 2017 Neutrons are unstable and free neutrons decay quite quickly. They are not fundamental particles, they are composed of quarks. OK TY Are quarks then always existing and lasting ?
imatfaal Posted June 11, 2017 Posted June 11, 2017 Quarks can certainly be created; pull two quarks away from each other hard enough and the colour confinement mediated by gluons is so tough that the energy required to pull the quarks apart is enough to created two new quarks - one paired with each of the original pair you were trying to separate. I don't think it is believe that you ever get a single quark by itself - so the issue of decay is, to an extent, moot. Within hadrons quarks definitely decay - to other quarks top -> bottom -> charm -> strange -> up <-> down These are flavour transformations mediated by the Weak force and involve W vector bosons which in turn decay into leptons and neutrinos
Sensei Posted June 11, 2017 Posted June 11, 2017 (edited) We use methods to date ages of fossils by Carbon based methods but can we ever determine the age of a particular Particle or for that matter a Molecule of water I drink now as to when was it created ? Carbon C-14 radiometric dating method is NOT used for the real fossils. C-14 has half-life only 5730 years. It is used to date ancient organic based remains made by human, remains of human f.e. mummies etc. It works reliable only to ~ 50,000 years. To check date of rocks and minerals there is used radioactive isotope of Rubidium-87 for example. https://en.wikipedia.org/wiki/Rubidium-strontium_dating In this thread I showed some calculations: http://www.scienceforums.net/topic/104881-isochron-plots/?p=983374 Edited June 11, 2017 by Sensei
studiot Posted June 11, 2017 Posted June 11, 2017 I suppose some fool has to wonder if applying the relativity of the Twins doesn't mean that no two particles have the same age, whatever that means, since no two particles can have had identical trajectories through spacetime. 1
pavelcherepan Posted June 11, 2017 Posted June 11, 2017 Yes, I had the Impression that Neutrons are such fundamental Particles that are not newly created or destroyed except in the formative processes when the Matter itself was created. The OP was based on this. In the nuclear processes I thought that Neutrons which were part of Heavier Elements were released and not newly created. [latex]\beta^+[/latex] and [latex]\beta^-[/latex] decay types are responsible for creation and destruction of neutrons in the atomic nucleus respectively. In addition to that, free neutrons (not bound with protons in the nucleus) have a half-life of about 10 minutes before decaying into a proton, an electron and an electron neutrino. 1
Sensei Posted June 12, 2017 Posted June 12, 2017 [latex]\beta^+[/latex] and [latex]\beta^-[/latex] decay types are responsible for creation and destruction of neutrons in the atomic nucleus respectively. In addition to that, free neutrons (not bound with protons in the nucleus) have a half-life of about 10 minutes before decaying into a proton, an electron and an electron neutrino. It's electron anti-neutrino. I will add to this that on Earth free neutrons can be created by cosmic rays (mostly Solar wind), in the same reaction in which Carbon C-14 is made: [math]p^+ + p^+ \rightarrow p^+ + n^0 + \pi^+ [/math] (cosmic ray accelerated to relativistic velocity) [math] ^{14}_7N + n^0+ \rightarrow ^{14}_6C + p^+[/math] (neutron capture and ejection of proton to conserve energy/momentum) 1
pavelcherepan Posted June 12, 2017 Posted June 12, 2017 It's electron anti-neutrino. Thanks for the correction
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