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- #241
Ummmm.... Ed.... The laws of nature were in place before space and time. I've been saying that all along. But the laws of nature are not "things." They don't exist in material form.
The Second Law of Thermodynamics Precludes an Infinite Acting Universe
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- #242
It might be helpful for me to post this again....
It is possible for matter to have a beginning. In a closed universe the gravitational energy which is always negative exactly compensates the positive energy of matter. So the energy of a closed universe is always zero. So nothing prevents this universe from being spontaneously created. Because the net energy is always zero. The positive energy of matter is balanced by the negative energy of the gravity of that matter which is the space time curvature of that matter. There is no conservation law that prevents the formation of such a universe. In quantum mechanics if something is not forbidden by conservation laws, then it necessarily happens with some non-zero probability. So a closed universe can spontaneously appear - through the laws of quantum mechanics - out of nothing. And in fact there is an elegant mathematical description which describes this process and shows that a tiny closed universe having very high energy can spontaneously pop into existence and immediately start to expand and cool. In this description, the same laws that describe the evolution of the universe also describe the appearance of the universe which means that the laws were in place before the universe itself.
It is possible for matter to have a beginning. In a closed universe the gravitational energy which is always negative exactly compensates the positive energy of matter. So the energy of a closed universe is always zero. So nothing prevents this universe from being spontaneously created. Because the net energy is always zero. The positive energy of matter is balanced by the negative energy of the gravity of that matter which is the space time curvature of that matter. There is no conservation law that prevents the formation of such a universe. In quantum mechanics if something is not forbidden by conservation laws, then it necessarily happens with some non-zero probability. So a closed universe can spontaneously appear - through the laws of quantum mechanics - out of nothing. And in fact there is an elegant mathematical description which describes this process and shows that a tiny closed universe having very high energy can spontaneously pop into existence and immediately start to expand and cool. In this description, the same laws that describe the evolution of the universe also describe the appearance of the universe which means that the laws were in place before the universe itself.
edthecynic
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You don't even know what those words mean!!!!
edthecynic
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The Laws of nature say there is no such thing as nothing, and so does Vilenkin, he says only "close to nothing."
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- #245
- The early universe was radiation dominated
- After about 50,000 years, the density of matter exceeded the density of radiation for the first time, eventually dominating the universe.
- In the early universe, matter and anti-matter were being created equally out of the radiation
- pair production
- pair production is the production of matter and anti-matter in pairs
- two photons can produce a pair
- particle-antiparticle annihilation (the reverse process) is also possible
- pair production
- Anti-Matter
- What is anti-matter (anti-particles)?
- A type of matter which has the same mass as normal matter, but opposite charge
particle charge of particle anti-particle charge of anti-particle proton positive anti-proton negative neutron neutral anti-neutron neutral electron negative anti-electron or positron positive
- What is anti-matter (anti-particles)?
- Matter and anti-matter can be created in pairs from energy (or electromagnetic radiation)
- E = m c2
- E = energy
m = mass
c2 = speed of light squared (here just a constant of proportionality)
- E = energy
- For example
- energy -------->proton + anti-proton
energy --------> electron + positron
- energy -------->proton + anti-proton
- OR matter can annihilate in pairs
- proton + anti-proton ----------> energy
electron + positron (anti-electron) ---------> energy
- proton + anti-proton ----------> energy
- E = m c2
- In the early universe, matter and anti-matter were being created equally out of the radiation
- Very early universe (when temperature was 10 billion K)
- Due to high temperature photons had enough energy to create electron-positron pairs
- Great numbers of electrons and positrons exist in thermal equilibrium with the radiation
- As universe expanded, it cooled
- Universe when temperature was 1 billion K
- Photons now have too little energy to create pairs, so electrons and positrons are no longer in thermal equilibrium
- Radiation Era
- (The radiation era lasted for about 50,000 years)
- Planck Epoch
- First 10-43 seconds after the Big Bang
- No current theory of physics (quantum gravity) exists
- GUT (Grand Unified Theory) Epoch
- After 10-43 seconds, temperature fell to 1032 K
- Quark Epoch
- Creation of protons and neutrons continued for about 10-4 seconds
- Temperature drops below 1013 K, and protons and neutrons are no longer produced in pairs
- Lepton Epoch
- Ends when the universe is about 100 seconds old
- During this epoch, the leptons (electrons, neutrinos, and other light particles) are still produced in pairs, because they are light
- Ends when temperature drops below 1 billion K
- Nuclear Epoch (first few minutes)
- Protons and neutrons fuse into nuclei
- By the time the universe is about 15 minutes old, much of the helium had been formed
- Crossover from radiation to matter dominance begins at 50,000 years at a temperature of 16,000 K
- Matter Era
- Atomic Epoch
- Begins about 50,000 years after the Big Bang
- Atoms form and remain intact (electrons attached to nuclei)
- Electromagnetic radiation decouples
- Cosmic Microwave Background appears
- Ends 200,000,000 years after Big Bang
- Galactic Epoch
- Large scale structure and bulk of most galaxies form
- Lasts from 200,000,000 years to 3,000,000,000 after Big Bang
- Stellar Epoch
- Stars continue to form up to today
- Extends into the Dark Energy Era
- Atomic Epoch
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- #246
Ummmm.... Ed.... I've been saying that all along that the laws of nature were in place before space and time. But the laws of nature are not "things." They don't exist in material form.
edthecynic
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Just because you can copy and paste does not mean you understand what you posted, you don't!
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- #249
Wuwei
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According to the latest theories, the preexistence of the laws of nature means that there was a vacuum energy. The energy manifests as particles of all sorts. Particles and antiparticles continually popped up and annihilated. Locally the vacuum was swarming with radiation, and particles. So before the big bang the laws of nature dictated there were things that existed in material form.
"...the vacuum energy of free space has been estimated to be 10−9 joules (10−2 ergs), or ~5 GeV per cubic meter..."
Vacuum energy - Wikipedia
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- #251
Seems to me that particles popping into and out of existence isn't quite the same thing as what happened here. So saying that before the big bang the laws of nature dictated there were things that existed in material form doesn't mean that all of the matter in the universe existed in material form before the big bang but rather was created from nothing during the big bang. There's a reason cosmologists say the universe was created from nothing.According to the latest theories, the preexistence of the laws of nature means that there was a vacuum energy. The energy manifests as particles of all sorts. Particles and antiparticles continually popped up and annihilated. Locally the vacuum was swarming with radiation, and particles. So before the big bang the laws of nature dictated there were things that existed in material form.
"...the vacuum energy of free space has been estimated to be 10−9 joules (10−2 ergs), or ~5 GeV per cubic meter..." Vacuum energy - Wikipedia
en.wikipedia.org
But I agree - and I think so do the cosmologists - that the laws of nature existed before the universe was created.
Wuwei
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The vacuum energy isn't nothing. It can be experimentally detected through the Casmir effect in a pure vacuum. The Heisenberg energy-time uncertainty principle says that during an extremely short time interval a huge number of particles can be created. Some think that if the rare local event of a space time bubble with a number of particles large enough to create the universe happened, and was above a certain density threshold it would exponentially expand and not collapse back into the sea of vacuum energy. Otherwise the bubble would collapse if it didn't reach that threshold.
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- #253
Is the vacuum energy equivalent to the energy in the universe?
Wuwei
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If you discount vacuum energy the total energy of the universe is said to be zero.
Some theories say the vacuum energy of the universe is the cause of dark energy that results in an accelerated expansion.
You have to remember that there are many theories of the origin of the universe. Some of them are more convincing than others. There are still many unknowns of the effect of vacuum energy at large scales. Vacuum energy is one of the things that makes it difficult to unite quantum mechanics with general relativity.
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- #255
Ok. Is the vacuum energy equivalent to the energy in the universe?
Wuwei
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That is not known. Vacuum energy at the scale of the universe is not well understood. Different universe theories about the meaning of vacuum energy and it's magnitude abound. There is also a question of dark matter matter playing a part in the vacuum energy?
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- #257
Ok, are you arguing the universe could have been created from pre-existing matter that was always there?
Wuwei
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It's not my argument. Many physicists argue that the laws of physics had to be operable before the big bang, and the physics dictates vacuum energy. Simply calling it pre-existing matter misses the essence of the point.
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- #259
But that's effectively what they are claiming, right? That that energy always existed, right? I'm just trying to understand the claim.
Wuwei
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That's right the claim is the vacuum energy always existed. Calling it "matter" is misleading. That term is sort of reserved for stuff like hubcaps and electrons through a wire.
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