# when there are no more particles...

Discussion in 'Physics & Math' started by Avatar, Jun 8, 2003.

1. ### Avatarsmoking revolverValued Senior Member

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19,083
or "below everything", what is in the basis of all particles (antimater, whatever). waves?

3. ### willson13The Villiage IdiotRegistered Senior Member

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136
Just for the record, I have no f***ing idea.

5. ### letheRegistered Senior Member

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2,009
uhh.... can you rephrase that? i have no idea what you re asking here. "below everything"?

7. ### Avatarsmoking revolverValued Senior Member

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19,083
I did put it in "*"
I mean - of what do particles consist of (if consist is the right word)
when you can no longer divide a particle is it still made of something, can that something be some kind of waves

sorry - I'm myslef messef up in this

8. ### letheRegistered Senior Member

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2,009
oh i see. i think you re asking "what are the most basic constituents of matter?", right?

like, first we thought that everything was made of atoms. then we discovered that atoms were made of electrons and nuclei, then we discovered that nuclei were made of neutrons and protons, and then we discovered that neutrons and protons were made of quarks. when does it all stop? what are the smallest particles?

well according to the standard model, it stops there. everything is made of quarks and electrons. they are the most fundamental particles.

however, you might ask, are quarks and electrons made of something? well, they might be. we just don t know. i don t think anyone believes that they are, and there are some aesthetic reasons to believe that they really are the fundamental particles. but one day, when our particle accelerators are 10 000 times more powerful than they are today, we may discover that electrons are really made of smaller particles.

but there is a theorem that says that even if our quarks and electrons are made of smaller particles, at low energies (like the ones currently attainable in our particle accelerators), they will still look like fundamental particles. so we can never know for sure.

i once read a pop science book when i was a kid that said that there were hypothetical particles that the quarks were made up of, called rishons. i am now a physicist, working in fundamental particles, and i have never ever heard rishons mentioned in any kind of scientific setting, so i don t know where they got this idea, but just so you know, people do occasionally think about things like this. but until our particle accelerators get powerful enough to test this, this is rampant speculation, not science.

so, simple answer: quarks and leptons.

9. ### BeerculesRegistered Senior Member

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342
Fundemental particles will never go away, but can be converted into other particles. In the universe, I think the lowest state you can get is a heat death scenario where everything is in the form of radiation, with the associated particles.

10. ### BlindmanValued Senior Member

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1,425
Are you talking about the cold (heat??) death of the universe..
That is.. It will expand forever. All things will fall into black holes and then eventually radiate as "Hawking's radiation"(Must spell check). We will then have no particles.

So what is Hawking's radiation anyway????

11. ### AndersHermanssonRegistered Senior Member

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What proof have we that Quarks exist btw?

12. ### blackholesunRegistered Senior Member

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636
The proof is in the atomic pudding. The standard model predicted the various quark particles. When we started finally reaching accelerator energies of the quarks' range, we would see the extremely quick decay byproducts of quarks into various other particles as quarks don't really like being by themselves. I got this off another site:

For example, when we bounce electrons off of protons and neutrons, the pattern of scattering angles observed is characteristic of point-like spin-1/2 scatters. The relative rates for electron versus neutrino scattering is that predicted from the quark electric charges. The process of electron-positron annihilation to quark pairs gives similar characteristic predictions, all these are also confirmed experimentally. The accumulation of many such results, where experiments match predictions based on quarks, convinces us that quarks are real.

Last edited: Jun 13, 2003
13. ### LocoRegistered Member

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When things fall into black holes, they don't dissapper. They just get a hell of a huge mass. Or something like that, I don't know if anyone have proven what a black hole actually is, so I should perhaps just shut my mouth, shouldn't I? Well, one thing is for sure. If all particles were gone, we could be sure they had just turned into energy of some kind. I don't know this for sure, but I don't think it has to be radiation. But at least they are not gone, because matter og energy cannot disappear.

Andreas

14. ### John Devers(AVATAR)Registered Senior Member

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120
I think this may interest you guys.

The Big Rip

http://xxx.lanl.gov/abs/astro-ph/0302506

Phantom Energy and Cosmic Doomsday
Authors: Robert R. Caldwell, Marc Kamionkowski, Nevin N. Weinberg
Comments: 4 pages, 2 figures, latex
Cosmologists have long wondered whether the Universe will eventually re-collapse and end with a Big Crunch, or expand forever, becoming increasingly cold and empty. Recent evidence for a flat Universe, possibly with a cosmological constant or some other sort of negative-pressure dark energy, has suggested that our fate is the latter. However, the data may actually be pointing toward an astonishingly different cosmic end game. Here, we explore the consequences that follow if the dark energy is phantom energy, in which the sum of the pressure and energy density is negative. The positive phantom-energy density becomes infinite in finite time, overcoming all other forms of matter, such that the gravitational repulsion rapidly brings our brief epoch of cosmic structure to a close. The phantom energy rips apart the Milky Way, solar system, Earth, and ultimately the molecules, atoms, nuclei, and nucleons of which we are composed, before the death of the Universe in a Big Rip''.

http://www.nature.com/nsu/030609/030609-7.html

Universe can surf the Big Rip

Alternative proposed to dark energy's cosmic doomsday.

11 June 2003
PHILIP BALL

The Big Rip is a break down of all the forces of nature.

The end of the world is not so nigh. A Spanish scientist has found a loophole in the suggestion that there might be a Big Rip in the universe about 22 billion years from now.

Earlier this year, US researchers showed how the recent discovery of an accelerating universe raises the possibility that in future everything may rend asunder, starting with clusters of galaxies and ending with the smallest of subatomic particles2.

Now Pedro González-Díaz of the Consejo Superior de Investigaciones Científicas in Madrid is arguing that, even if the universe is built the way Big Rip proponents suggest, a cosmic doomsday is not inevitable. The universe might just go on expanding, he says.

Given the timescales involved, we needn't start fretting too much either way. But there's no denying how terrible the Big Rip sounds. It is a kind of breakdown of all the fundamental forces of nature, as empty space becomes so full of energy that it overwhelms them. When that happens, everything falls apart.

Phantom menace
The destruction begins, say Robert Caldwell of Dartmouth College in New Hampshire, USA, and his coworkers, about a billion years before it ultimately ends in a Big Rip. First, gravity loses its grip at cosmic scales, allowing clusters of galaxies to drift apart.

Sixty million years before doomsday, our own galaxy, the Milky Way, fractures as stars slip from each other's grasp. A few months before the end, planetary systems like the solar system will be dismembered, and 30 minutes before the Big Rip, the planets and stars themselves disintegrate.

In the split-second before the end, atoms and molecules are torn apart, then the particles that constitute them. Finally, space itself flies open.

All of this is driven, the argument goes, by something known as phantom energy, which fills all of space. The density of phantom energy increases with time, like a bomb that grows ever bigger.

Energy bar

No one knows if phantom energy exists at all. But recent astronomical observations hint that it might.

Five years ago, astronomers found that the universe is expanding at an ever-accelerating rate. The cosmic speed-up suggests that space is permeated by dark energy, creating a kind of pressure that opposes the pull of gravity.

One explanation for this dark energy reinstates the idea of a cosmological constant, which Albert Einstein first proposed and then rejected in the early twentieth century. According to this hypothesis, the universe will merely expand forever, with distant galaxies gradually winking out of sight.

An alternative possibility is that the dark energy takes the form of so-called phantom energy. This is more pathological than the dark energy supplied by a cosmological constant, Caldwell and colleagues say. They point out that phantom energy will become ever more dominant over other kinds of matter and energy as time progresses.

In the split-second before the end, atoms and molecules are torn apart, and then the particles that constitute them

Or perhaps not. González-Díaz points out that some kinds of phantom energy can be well behaved, avoiding the blow-ups and instabilities that lead to a Big Rip.

Dark energy can be thought of as a kind of gas filling all of space, the density of which is proportional to its pressure. González-Díaz shows that if one assumes that this 'gas' has certain properties - specifically, that the speed an oscillation passes through it decreases with time - then there is no longer a Big Rip. This might sound contrived, but actually, González-Díaz reckons it is a more realistic kind of behaviour than the alternatives.

To settle the debate over what's in store for the Universe, astronomers will have to probe deeper into how it looked soon after the Big Bang, and how it is expanding now. Questions like this are being investigated by the Wilkinson Microwave Anisotropy Probe (WMAP) satellite operated by NASA.