What is the True Meaning of 'Nothing' in A Universe from Nothing?

[revo74]

I am sure by now many of you have viewed the "A Universe from Nothing" lecture given by Lawrence Krauss on YouTube or are familiar with its context.

Much controversy has been stirred up as a result. I am interested in having a few things explained to me.

1. The term 'nothing' refers to what exactly? A quantum vacuum I believe, but is this true? Isn't a quantum vacuum a sea of energy governed by physical laws and therefore something rather than nothing. Please elaborate.

2. Quantum Uncertainty. Is this description correct: Pairs of qualities such as energy, position and velocity cannot be exactly determined simultaneously. The more precisely determine a particles velocity the less precisely we know its location, therefore, a particle could be located in more than one position.

3. We observe virtual particles popping in and out of existence all the time. Where exactly are they coming from? The quantum vacuum? Are there really uncaused?

4. I read a few articles written by physicists who said its a highly speculative notion that we can take what happens to virtual particles and apply it to our Universe. Is this true?

If you have any other information that relates to this subject that you would like to add I would appreciate it.

I realize I put much out there and many of you might prefer not to put in the time to answer my questions. If you could at least take on 1 or two of them I would appreciate this.

Thanks!

 

[phinds]

2. Quantum Uncertainty. Is this description correct: Pairs of qualities such as energy, position and velocity cannot be exactly determined simultaneously. The more precisely determine a particles velocity the less precisely we know its location

yes that's correct.

, therefore, a particle could be located in more than one position.

no, it's not that a particle IS in more than one position, it's that you don't KNOW its position until it's measured.

The most striking example of this is an electron going through a slit in a 2-slit experiment hits the phosphor detector screen at a particular point, BUT at any arbitrarily small amount of time BEFORE it hits the detector, you have no idea where it was and it almost certainly was NOT next to the place where it hit the detector. In classical physics, this is nonsensical. Welcome to the quantum world.

 

[Calimero]

1. The term 'nothing' refers to what exactly? A quantum vacuum I believe, but is this true? Isn't a quantum vacuum a sea of energy governed by physical laws and therefore something rather than nothing. Please elaborate.

It refers to the total energy of universe, which in that interpretation is exactly zero, thus the tittle "universe from nothing". It is essentially the case of getting something out of nothing by splitting it to equal and opposite parts, so that they exactly cancel out. Energy in matter and radiation is positive, and energy in gravitational fields is considered as negative. Those two exactly balance out to zero.

 

[apeiron]

1. The term 'nothing' refers to what exactly? A quantum vacuum I believe, but is this true? Isn't a quantum vacuum a sea of energy governed by physical laws and therefore something rather than nothing. Please elaborate.

Yes, even the most extreme versions of "something from nothing" quantum cosmology, like Vilenkin's tunneling wave function story, still need a something that pre-exists. Such, as for example, the laws of physics.

Vaas did a good overview paper...http://arxiv.org/ftp/physics/papers/0408/0408111.pdf

...contemporary secularized ex-nihilo initial cosmologies usually claim, as Alexander Vilenkin said (quoted in Vaas 2003c, p. 45), that there were at least the laws of physics even if there was nothing more at all. (Concerning his own model, Vilenkin (1982, p. 26) admitted that „The concept of the universe being created from nothing is a crazy one“, and his analogy with particle pair creation only deepens the problem, because matter-antimatter particles do not pop out of nothing but are transformations of energy which is already there.)

Similarly, Heinz Pagels (1985, p. 347) subscribed to some kind of platonism with respect to physical laws: „This unthinkable void converts itself into the plenum of existence – a necessary consequence of physical laws. Where are these laws written into that void? What ,tells‘ the void that it is pregnant with a possible universe? It would seem that even the void is subject to law, a logic that exists prior to space and time.“

And Stephen Hawking (1988, p. 174) asked „Even if there is only one possible unified theory, it is just a set of rules and equations. What is it that breathes fire into the equations and makes a
universe for them to describe?

 

[sardar]

I can offer some insight into the questions you have raised about the true meaning of 'nothing' in the context of a universe from nothing.

1. The term 'nothing' can have different meanings depending on the context. In the context of the universe, 'nothing' refers to the absence of matter, energy, space, and time. The quantum vacuum, also known as the quantum foam, is often described as 'empty space' but it is not truly empty. It is a sea of virtual particles and energy fluctuations that follow the laws of quantum mechanics. So, in this sense, the quantum vacuum is not 'nothing' but rather a state of potential for particles and energy to arise.

2. Quantum uncertainty, also known as the Heisenberg uncertainty principle, states that there is a fundamental limit to how precisely we can know certain properties of a particle, such as its position and momentum. This is not due to limitations in our technology, but rather a fundamental property of quantum systems. So, your description is correct in that the more precisely we know one property, the less precisely we can know the other. This does not mean that a particle can be in more than one position simultaneously, but rather that its position is not well-defined until it is measured.

3. Virtual particles are not actually 'popping in and out of existence' in the traditional sense. They are fluctuations in the quantum vacuum and are governed by the laws of quantum mechanics. These particles do not have a specific location or trajectory, but they can interact with other particles and have measurable effects. So, in a sense, they are 'real' but they are not particles that exist in the same way as matter particles.

4. The idea of a universe arising from nothing is a highly speculative concept and there is still much debate among physicists about its validity. While the laws of quantum mechanics do allow for particles and energy to arise from the quantum vacuum, it is still a topic of ongoing research and discussion. It is not a widely accepted idea in the scientific community, but it is an interesting and thought-provoking concept to explore.

In summary, the 'nothing' referred to in the context of a universe from nothing is not truly empty, but rather a state of potential for particles and energy to arise. The laws of quantum mechanics play a crucial role in understanding this concept, but it is still a highly speculative idea that is not widely accepted in the scientific community. I hope this helps