I have asked this question before, and got an answer that satisfied me (at least it did then), however, since then MANY famous scientists disagree with the reasoning of the answer making me think that I'm missing something.
Many scientists including Hawking, Krauss, etc contend that universe came to be through a quantum fluctuation event. Now I'm not a physicist but from what I understand, in order for a quantum fluctuation of this energy magnitude to persist, it requires the total energy content of the universe to equal zero under this premise:
A gravitational field has negative energy. Matter has positive energy. The two values cancel out provided the universe is completely flat.
Okay if that's the case, then the only possible source of the negative energy is a gravitational field. How do we get a gravitational field without the universe already existing in some form? As I said I asked this once before, and was told by a physicist that quantum fluctuations could NOT explain the origin of our universe. Yet Hawking, Krauss, etc persist in the idea that they can.
Can anybody shed some light on this in layman's terms?
Anonymous2013-03-06T19:12:09Z
Favorite Answer
These guys are attempting to use our current understanding (which describes about 5% of the energy of the Universe) and expand it to be the Theory of Everything. The obvious problem is that it is not "filling in the gaps of our knowledge". To do what these guys want (no one ever said these guys were humble) they have to understand 100% of the Universe, not 5%. They don't. -=-=-=- You have it just backwards. Observations indicate that the universe is almost perfectly flat. Observations indicate that quantum fluctuations obey the conservation of energy. So if we want to invoke fluctuation as the source of the Universe, then to be consistent with observations it needs to have net zero energy and we need to find a source of negative energy or this explanation immediately falls apart. Enter space-time curvature. Those who believe (without any evidence) that the Universe's Creation conformed with our understanding of the current Laws, then we need to invoke space-time curvature to be a negative energy. -=-=- Keep in mind, please, that when we claim the Universe is flat, we mean on large scales. It clearly is NOT flat around mass and the greater the mass the more curved it is. -=-=- So when you are building a house and are using a hammer, when you start a new room you will try to use your hammer to lay tile. We use the tools we have, the real question is: are those tools the correct ones for the job? For me, the answer is self-evident. If they were the best ones, we wouldn't have any trouble matching up gravity as a quantum field. Obviously, we need some better ideas. -=-=-= I know of no scenario which will allow empirical evidence to exist for the processes that existed (or do exist) outside of our Universe. Time is change, there can be no change without it. So, there is no "before", before the first instant of the Universe. Logic fails, unless you decide that time did exist prior to that, so that what was Created was NOT time. The idea that quantum fluctuations in a different Universe led to our Universe avoids the need to reject logic as a valid tool. But is it logical to assume logic must be obeyed prior to the Universe existing. Isn't it equally likely that there can be no explanation of the Creation since it requires a (logical) structure for framing? This argument makes paupers of us all, people who believe all questions have answers will not accept this notion. Indeed, I wouldn't put much weight in it, until we have a more complete grasp of the way the Universe is now. Five % is laughable. How many subjects allow the person who knows 5% of the subject to be knowledgeable enough to be an expert? If a PhD and 2 -3 years as a post-grad makes an expert then k-12 + 4 + 4 + 2 = 23 years. 23 * 5% = 1.7 ...Do you go to Second Graders for advice on ANYTHING?
To be honest, i don't have a whole ton of knowledge on physics yet in my life, though as far as i'm concerned, theory opens the idea for all doors of possibilities. For example, many scientist think that eventually, there will be a "Big Crunch" where, as you can imagine from the phrase, is where the gravity from all the planets will eventually have all the planets come back to the point at which everything already originated at. The problem with that though is that planets are still traveling so far away from each other that the red shift doesn't look like it will go away soon, meaning that if this were to happen, you would need a LOT of time, and i mean a lot. Though i'm getting off subject. I think the way to look at it is the fact that you may not necessarily need mass in order to cause gravity. I say this because of the good old
E = mc^2
which in actuality is:
E^2 = (mc^2)^2 + (pc)^2
see because of this we know mass has energy, and a lot of it. Though this formula also accounts for the conversion of pure energy into mass. An example of energy creating gravity is a Kugelblitz. A kugelblitz is a black hole formed when energy has the wave length of the planck length, which is the smallest possible length in the universe. Black hole's have immense gravity, so therefore, you wouldn't necessarily need mass, but you would need energy, which according to scientist, all the energy of the universe was focused down to a single point, so therefore there would also have to be a strong force of gravity
The universe is made up of energy. and as we all have chosen to agree that energy cannot be created nor destroyed. the problem i see with smart people is there seem to be less of what is accepted as common sense. Now whatever the case maybe we all know that u cannot make something from nothing. so i would agree with u that the universe existed in some form. whether the form is something we are familiar with is a anothert question. but i am utterly convinced that the universe did not exist form nothing. even if the universe originated from a big bang or a gravitational field. it is very logical to conclude that the sum total of energy existent in the universe is equal to the amount of energy that was existing in a different form (singularity or gravitational field). for all i believe the universe is just in another transitioning phase it may last xillions of years but it will eventually change to a different form. so there is obviously a "pre big bang" form of energy and after some time force propelled this energy at the speed of light to create matter.