Age Paradox Perhaps

[PsychoticEpisode]

Is there a particle as old as the universe? Since the beginning of the universe every particle known to exist has been in motion. At least I have never heard of a particle that is permanently at rest. Thus each individual particle has aged differently and independently from the other. In fact it may be very hard to find two particles with exactly the same age. Anyway I don`t think it really matters in the great scheme of things.

The universe and all it entails is presumed to have come into existence at the same time, the beginning. If the universe results in a big crunch and a general recycling occurs then do all particles that are part of a reborn universe have the same starting time in the new universe? If there is a cyclic nature to the universe then time may not have a beginning at the most recent BB. The particles, whether they be crushed into a point or be allowed to haphazardly migrate through space, are just being themselves, randomly reacting to the prevailing forces.

I understand that time itself may be non existent at a singularity but if matter is being recycled then does time really stop? So if every particle will someday be recycled then is it really safe to say time began at the moment recycling occurs? The recycled matter, is it as old as a newly created universe or as old as time itself? If it is then any recycled universe is much younger than the particles in it.

In summary: if our universe is the first and the one and only, then the particles are younger than the universe but if our universe has been recycled then the particles or matter are much older. Time itself may not have a beginning at the moment our universe was formed if indeed it was reborn.

[quantum_wave]

I guess no one is going to tackle this so let me have a go at it.

It seems as though some people like you and I go off thinking about things that we cannot ever really know the answers to for sure :). The age of particles, how special relativity affects the age of particles in different frames, the possible recycling of particles in big crunches, and ultimately was there one beginning, multiple beginnings, or no beginning at all are those types of questions.

My best speculative thinking is that particles do not survive the recycling if the recycling involves a big crunch. Particles as we know them might be completely converted to a form of dense state energy deep inside such a big crunch. The recycled particles might emerge from the crunch as a burst of dark energy that expands until the energy density declines enough for particles to reform.

If that speculative scenario were to be true then it would conserve energy, allow for time to be potentially infinite, and might make for many new beginnings utilizing the same energy. This would comply with the idea that energy cannot be created or destroyed and would mean that energy potentially could have always existed.

From there the nature of the universe could take many forms and the landscape of the greater universe may include many arenas where big bangs and big crunches occur here and there. But such speculation is not easy to do without running into problems with the evidence, data, and observations. Many such ideas can be falsified by showing they are not compatible with existing data so don't get to attached to any speculative ideas until you have explored them and allowed the community to falsify them with the data.

I hope that gives you something to think about without discouraging your speculative interests.

[PsychoticEpisode]

I guess no one is going to tackle this so let me have a go at it.

Thanks. I wasn't sure if what I said made any sense. Then again, if it did then I didn't think it would make any difference. I'm just thinking out loud.

I wasn't trying to suggest particles survive a crunch but that they would again become matter in a reborn universe.

[quantum_wave]

Thanks. I wasn't sure if what I said made any sense. Then again, if it did then I didn't think it would make any difference. I'm just thinking out loud.

I wasn't trying to suggest particles survive a crunch but that they would again become matter in a reborn universe.My pleasure. There is a speculative basis to that idea that we could agree on :).

[James R]

Is there a particle as old as the universe?

Most likely not. The first particles were photons, but they were all interacting in the first few minutes after the big bang, being absorbed and emitted constantly. There are probably some protons and electrons that are still around from not too long after the big bang, though.

...Thus each individual particle has aged differently and independently from the other.

Particles don't "age". If you pick up two electrons, there's no experiment that you can do that will tell you which one came into existence earlier. They are indistinguishable. In fact, it goes deeper than that. The two electrons are guaranteed to have absolutely identical properties, in terms of electrical charge, spin ... anything that identifies them. Some fundamental results in quantum physics depend on the fact that fundamental particles are indistinguishable. If they were not, experiments could be done to show that they were not.

If the universe results in a big crunch and a general recycling occurs then do all particles that are part of a reborn universe have the same starting time in the new universe?

Presumably, all particles would convert back to photons just before any big crunch. The energies involved would be huge.

As for "recyling", remember that mass and energy are interchangeable. If anything is passed from one universe to the next, it will most likely be energy, not particles.

[PsychoticEpisode]

Particles don't "age". If you pick up two electrons, there's no experiment that you can do that will tell you which one came into existence earlier. They are indistinguishable. In fact, it goes deeper than that. The two electrons are guaranteed to have absolutely identical properties, in terms of electrical charge, spin ... anything that identifies them. Some fundamental results in quantum physics depend on the fact that fundamental particles are indistinguishable. If they were not, experiments could be done to show that they were not.

If I have two electrons at rest and I accelerate one close to the speed of light for a while, decelerate it and again place it next to my other electron then there is no difference in age? From my perspective, wouldn't the electron that was in motion be younger?

I must be confusing aging with being older or younger. There is no age distinction between an old particle and a new particle then? If aging does not apply to particles then how does particle decay figure into it? If particles decay into something else less than a second after the BB then wouldn't the decaying particle have had a lifetime?

[Acitnoids]

The half-life of a partical is a statistical approximation. Think of it like this. Lets say you want to make popcorn. All of the kernels are placed into hot oil at the same time. Even if all of the kernels had the same size and density they would not all "pop" at the same time. You could calculate how many kernels will pop over a given amount of time within the heat of the oil or even how many kernels will not pop in that same time frame but you will never know when any specific kernel will pop.

[PsychoticEpisode]

The half-life of a partical is a statistical approximation. Think of it like this. Lets say you want to make popcorn. All of the kernels are placed into hot oil at the same time. Even if all of the kernels had the same size and density they would not all "pop" at the same time. You could calculate how many kernels will pop over a given amount of time within the heat of the oil or even how many kernels will not pop in that same time frame but you will never know when any specific kernel will pop.

In reference to their ages, would I not need to know that all the kernels came from the same stalk? I could mix one year old kernels with two year old kernels, no?

Anyway I get what you're saying. A particle, regardless of any age will decay at an unpredictable time.

[EmmZ]

So, if there are no particles as old as the universe, particles magically appeared from nothing? Your universe sounds a bit mythical to me.

[D H]

In reference to their ages, would I not need to know that all the kernels came from the same stalk? I could mix one year old kernels with two year old kernels, no?
Actinoid specified that "all of the kernels had the same size and density". Add chemical composition to that list and you have something that is a reasonable analogy to elementary particles in the sense that kernels are completely indistinguishable. One versus two year old kernels of corn will have different densities and different chemical compositions; they are easily distinguishable.

Free neutrons have a half life of about 10 minutes. (10.23, actually; call it 10 to make the numbers nice.) Suppose you release one neutron every 30 minutes into a vacuum chamber and watch for the decay. Suppose the neutrons enter the chamber with a fixed non-zero velocity. (This will let you distinguish "old" neutrons from newly born ones based on their position.) One out of eight neutrons will live 30 minutes or more; you will have to track two, maybe more, neutrons. Suppose a neutron does live for the 30 minutes between releases. What are the odds this 30 minute old neutron will live longer than the one just released? The answer: 50/50. Suppose a neutron lives for 120 minutes. The odds this 120 minute old neutron will live longer than the one just released is still 50/50.

Popcorn kernels lose moisture and change chemical composition as they age. Nothing like that happens to neutrons. The only thing that distinguishes the neutrons in the above thought experiment is their location. Sans that artificially imposed distinguishing characteristic, there is no way to tell the difference between the neutrons that lived for 30 minutes and 120 minutes from a newly released neutron. Neutrons don't age.

[jmpet]

The universe is not that old- sure- there's lots of original Big Bang hydrogen atoms in the universe floating around in space- you're probably breathing some of them in right now. We (us humans in the solar system in the present) are only 2nd or 3rd generation matter. What's the half life of a hydrogen atom- something like 2 trillion years.

[PsychoticEpisode]

Does the possibility exist that the first particles in our universe may have had origins in another universe or any other outside source? If so then all matter could be older than our universe. That is unless our universe has been around since the beginning, albeit only as an empty container or grew as a polyp from another universe.

[kaneda]

We can have no way of knowing how old particles are. If we lived it in a steady state universe, there would have to be a process of renewal, possibly involving black holes so there could be particles a hundred billion years old and particles just a million years old.

Particles are distinct from photons in that one cannot reach the speed of light while the other always travels at light speed. There is no threshold at which one becomes the other. It is claimed that matter has become energy on Earth but that is nonsense as a force a million times more powerful has failed to do the same to this OMG particle:


http://en.wikipedia.org/wiki/Ultra-high-energy_cosmic_ray


However it started, I think matter appeared with energy. To say just energy appeared is like saying just gravity appeared.

[James R]

If I have two electrons at rest and I accelerate one close to the speed of light for a while, decelerate it and again place it next to my other electron then there is no difference in age?

No observable difference, no. To measure the elapsed time for an electron, you'd need to send a whole lot of apparatus riding along with it.

Think about this: I give you two electrons - one of which was produced in a particle collision a few days ago and one of which has been in a piece of graphite formed 500 million years ago. What experiment are you going to do to tell one electron from the other?

If aging does not apply to particles then how does particle decay figure into it? If particles decay into something else less than a second after the BB then wouldn't the decaying particle have had a lifetime?

The "lifetime" of a radioactive particle is simply a measure of how long that particle lasts on average. But there's no internal clock ticking off the age of the particle until it decays. Radioactive decay is a random process.

It is claimed that matter has become energy on Earth but that is nonsense as a force a million times more powerful has failed to do the same to this OMG particle

kaneda has obviously never heard of nuclear weapons.

[kaneda]

James R. A moving particle has energy. It is nonsense to say that the particle is a solid form of energy. Why can that energy not be removed from the particle? It could be a form of DM, as in particles in space with no energy.

Perhaps you would like to give the threshold at which matter changes into energy and explain why it does not happen with cosmic rays? Thought not.

[James R]

James R. A moving particle has energy. It is nonsense to say that the particle is a solid form of energy.

I don't remember saying that a particle is a solid form of energy.

Nevertheless, it is true that every particle has rest mass energy. This means that it has some energy even when it is not moving, as Einstein showed with his most famous equation.

Why can that energy not be removed from the particle?

It can be. Collide a proton and an antiproton together, for example, and both particles disappear, releasing their energy. This is happening in a particle accelerator somewhere right now, as you read this.

Perhaps you would like to give the threshold at which matter changes into energy and explain why it does not happen with cosmic rays? Thought not.

It does happen with cosmic rays. For example, high-energy cosmic rays (photons) hitting the upper atmosphere commonly release their energy, creating pions. These pions then decay further into various particles including muons. I personally have conducted an experiment to detect muons falling from the sky, so I can confirm that they do exist.

The threshold you asked about depends on the particular process you're talking about, so I can't give you a generic answer. There are too many processes to go through all of them.