Given the First Law of Thermodynamics: that you can't get something from nothing. Where did all the stuff in the universe come from and how is it still a law if it was once broken?Asked by: Rob
AnswerThe law you cite, applies only to 'closed systems', i.e. where nothing can be added or subtracted from the 'specimen'. Obviously if you apply the law to an empty box, then open the box and dump in a handful of sand, or quarks, or energy, you don't expect the law to apply, because the system is not 'closed'.
It is not known whether the universe as a whole is a closed system now at present. As far as conditions preceding and at the very moment of the 'big bang', we can only speculate whether the universe was closed, or open (to another, larger system), or whether the First Law (or lots of other laws) even applies under those extreme conditions.
Answered by: Grant Hallman, Ph.D., Universtiy of Toronto, 1971/1967
In the macroscopic world, the domain of 'classical' physics, the laws of thermodynamics are, and have always been, true.
However, on the quantum scale, it is a very different matter. Hiesenberg's uncertainty states that there will always be a level of uncertainty when you try to make measurements of particles and other quantum scale occurrences. You can never know everything about a particle's position and motion at any one time. This is an intrinsic uncertainty, it is not due to limitations on our measuring devices. This uncertainty of the energy of anything of the Planck scale is size allows some very bizarre phenomena to occur.
To us, vacuums appear to contain nothing at all. But, it you were to look closely, very, very closely (to the order of 10^-35m), space is actually a foaming mass of quantum activity. This quantum foam is made of particles and micro-black holes popping in and out of existence, apparently in contravention of the second law of thermodynamics, they appear out of nothing with energy, then disappear again just as quickly. The key to this is the uncertainty principle. The disturbance is permitted to 'borrow' a tiny amount of energy and exist for a very short length of time, and then it must return the energy and disappear again. But, the more energy it borrows, the less time it is allowed to exist. These 'temporary' particles, called virtual particles, are not just theoretical, they have been proven to have real effects on scientific experiment.
The only thing that prevents these virtual particles from coming into permanent existence is a lack of energy. However, it is possible to artificially supply energy to the particles therefore promoting them into reality. This could be done in a lab by creating very strong electric fields, but these fields are very difficult to create. On the other hand, intense gravitational fields could also do the job.
It is possible that during the big bang, black holes the size of a nucleus popped into existence due to the quantum foam. The interesting thing is that the smaller a black hole is, the more strongly space-time is distorted around it and distortions in space-time imply the existence of very strong gravitational fields. Stephen Hawking has shown that the gravitational field around such a hole would give enough energy to the quantum foam to promote the particles into real existence. Calculations show that in the big bang the initial extreme conditions would also have been enough to create real particles out of the gravitational energy of the rapidly expanding universe.
And as for how the universe actually came into being itself, it is believed that also in the quantum foam, virtual space-time bubbles also continually pop in and out of existence, like virtual particles, only to disappear again. However, it is possible that one of these space-time bubbles, which is actually an unimaginably small universe, could avoid rapidly disappearing again and be promoted to a full size universe, such as ours. However, for this to work some sort of repulsive force is needed, a sort of anti-gravity. Many scientists believe in the existence of such a force at the time of the creation of the universe, but as I've answered your question and that's a whole other topic, I think I'll stop before I go off on too much of a tangent.
To summarise, due to the uncertainty principle, particles and space-time bubbles continually pop in and out of existence for short times depending on their energy, without breaking the law of conservation of energy as they dissapear again. Think of it like an accountant (the universe) who balances the books at the end of every month. If someone (a virtual particle) was to borrow some money on the 4th day of the month (pop into existence)then put it back on the 8th day,(disappear again) then as far as the bookkeeper would know, nothing had gone amiss and no rules (or laws) had been broken. If a particle is to come into complete and real existence, it must take its energy from somewhere, such as a gravitational field.
Answered by: Simon Hooks, Physics A-Level Student, Gosport, UK