I read Discover magazine every month, and this time it’s a doozy. The cover article is titled “Where did everything come from?” I quote:
Good question. I’ afraid the article just confused me though.
To paraphrase the article a bit: The main question here is “What came before the big bang?”. Alan Guth attempts to answer this question through his theory of “inflation”. He feels that quantum theory holds that probablities rule any physical system and that a vacuum is subject to quantum uncertainties. Apparently, this means that things can materialize out of the vacuum but tend to disappear back into it quickly. Theoretically, anything can pop into existence as a result. Probability suggests that pairs of sub-atomic particles (one positive one negative) are most likely. Guth suggests that the entire universe is one of these quantum fluctuations:
Now this is where it starts to confuse me. The article turns towards discussion of omega, which describes the ratio between the average density of matter in space and what that density would need to be to make the Universe perfectly flat. Apparently, based on microwavee radiation measurements, the value of omega appears to be very close to 1. He jumps quickly to the conclusion that the Universe erupted from a “false vacuum” popping into existence in a quantum fluctuation. Color me confused.
The article later moves on to the issue of conservation of energy. How could all of this just come to exist without violating this principal? I’ll quote the answer (I hope I’m not quoting to the point of copyright infringement, I really am just trying to understand & hopefully I am giving proper credit):
Huh? I am having a serious problem understanding how a universe that has billions of glaxies with trillions of suns that burn could have a net energy of zero!!! Gravity is negative??? How the hell can part of zero be positive energy? I understand that 1 + -1 equals zero, but I don’t see how you could adjust zero to get a 1 and a -1. I also have trouble understanding how particles can just “pop” into existence and still maintain the conservation of energy.
I’m way over my head here. Anyone think they can help a layman come to terms with this stuff?
There was a similar article in US News and World Report, which may explain things better. The journalist summed up by saying that a lot of these ideas are just hypotheses, or even conjecture. In other words, semi-educated guesses.
I understand that this is not the final word. I just want to understand the theory well enough to understand why it is likely (or even possible) for such a thing to be true.
I’m mostly having trouble understanding the idea that everything is nothing and nothing can create everything. In my mind it sounds like silly semantics and I am having trouble understanding the science behind such statements.
It’s like if I have zero and break it in half I would still have zero. Not 1 and -1. Right? Zero divided by ANY number equals 0. How can you get energy from nothing? What exactly is negative energy? If zero is the absence of anything than what is it to be negative? How can there be less then nothing? How can you have so much nothing that it is something?
As I understand it the theroy is that the singularity popped into existence as a quantum fluctuation and the unevenness in the microwave background radiation is good evidence for it. Some such as Stephen Hawking take this as removing the “need” for God as an explanation. I personally think it’s an incredibly cool way for God to have created the universe.
Doing what I do best, managing to piss off both sides of a debate.
Those who give credence to the “Many Worlds” theory of quantum physics would say that whenever numerous viable possibilities exist, the universe splits into many universes, one world for each different possibility. In each of these universes, everything is identical, except for that one different choice; from that point on, they develop independently, and no communication is possible between them. In this way, the metaverse or multiverse branches endlessly. What is the present to us, lies in the pasts of an infinite number of different futures. According to this theory everything that can happen, does, somewhere.
If this is true, our own universe popped into existence or “big banged” if you will as the result of a previous universe. When was the first universe and when will be the last? In this view there is no beginning or end, an infinity of parallel universes has been spawning an infinity of parallel universes, and so on and so forth in a never ending or beginning cycle, and that is the nature of reality, it simply exists. However, it’s just a theory and I’m not tied to it. It does satisfy me more than using God in the equation ever did though.
Scientists just love to have everything balance out to zero. Electric charge, action equals reaction and so on. So it would seem that Guth proposes a scheme whereby the current mass-energy can be balanced by some negative entity so that it all could have come from nothing.
If everything does indeed balance then there is at least a chance that it can be written down as an equation which allows the application of the shorthand of mathematics. If that can be done you’re on the way to making some sense of it.
The idea will stand or fall depending on the analysis of it by those who are competent to do so. Assuming anyone takes it seriously enough to bother, that is.
Guth describes gravity as having negative energy, which balances out the positive energy (contained in all the matter in the universe). So the universe is basically nothing becuase it cancels it self out - so there is no violation of the conservation of energy.
What?
This is my biggest problem here. I thought gravity was supposed to be the warping of space-time by matter? Is it actually a form of energy? A new experiment is being set up that will attempt to detect “Gravity Waves”. Waves? Again, metaphorically, I thought it was just the way we describe what happens when a ball (planet) is placed on a tablecloth (space-time). Gravity actually travels in a wave? Like light? Then what is the speed of gravity? Does not gravity act at great distances quicker then the speed of light? If it travels then it breaks the speed laws . . .
We don’t really understand gravity yet, do we? Can this guy Guth really say that it is a form of negative energy without talking out of his ass?
I have heard all of the multiverse theories a few of you mentioned. This is a little different, I think. It’s not stasting that everything that can exist does (or will) somewhere. It’s saying that it is possible for a universe like ours to just pop into existence out of nothing due to the natural laws of quantum mechanics.
For you trouble makers out there the next level of scientific inquiry is: “How did the natural laws get there?”
DaLovin’ Dj
(Who just can’t understand the gravity of the situation!)
When two objects that are gravitationally attracted to one another are allowed to “fall” toward each other, they speed up. Their kinetic energy increases. We say that they are turning gravitational potential energy into kinetic energy. As their kinetic energy increases, so, by good ol’ E = mc[sup]2[/sup], does their mass.
In order to separate those two mutually-attracted objects from each other in the first place, so that they have the opportunity to fall, you have to pull them apart. You have to add energy. The action of pulling them apart takes energy. Thus, this gravitational potential energy is always described as a negative number. A one kilogram object resting on the Earth has a gravitational potential energy of zero, relative to the Earth. A one kilogram object suspended one meter above the surface of the Earth has a gravitational potential energy of negative one Newton-meter.
What if they were never together? Maybe I’m being thick here. Let me see if I can get this.
The Big bang theory holds that everything was together at one time. So it all explodes outwards and the energy that sends all the matter flying is where this energy you speak of comes from. So all of this “gravitational potential energy” is stored in the space time fabric just waiting for matter to warp spacetime and release this energy. Close?
It seems like it’s not really negative enrgy per se, but more like a way of describing stored energy. Wouldn’t the energy that is added be positive to begin with? Now it seems like you need energy to create matter, and more energy to store in space-time to alllow gravity to work. How can this equal zero?
So far, dj, I think you’re proving yourself philosophically smarter than the physicist you read. Of course the physics equations of gravity & matter balance out. That’s a “by definition” kind of thing. He’s just dumb enough to try to reduce the universe to a one-dimensional, single-layer equation.
naw, it travels at the Speed of light in a vacuum
so, if the sun were to magically move 100 miles further away it would take 8 minutes for the change to take effect on earth.
on another topic, i too do not see how gravity can have negative energy in this particular case. Take a singularity such as the Big Bang, then separate the particles somehow. The particles have positive energy, since they have mass. If the particles were to pull together once again to a near-singularity, they would certainly have more speed, and, thus, energy, than they have presently, so I would have to say that it appears spreading out particles is not a good way of destroying or even cancelling out energy, since you can simply recapture that energy by moving the particles closer together. Now, in moving them away, you certainly lose energy since it takes energy to move them further apart, but we have already proven that we havent run out of energy since there is still mass in the universe. When you ADD the gravitational potential energy we can achieve by moving all the particles of the universe closer together we certainly have more than zero???
That is flattering, but I don’t know if it’s really deserved. I can’t help but think my problem here comes from a misunderstanding (perhaps even complete ignorance of) the proper physics concepts. I must say I am getting even more confused.
I always thought this was not true. I thought the effect would be instant. All of space time would warp way faster than light would travel to the same spot. I thought that was a major reason why the “speed of gravity” was an issue that is on the fringe, but very interesting.
If I remember correctly, counter arguments to gravity moving faster than light explain it away by pointing out that gravity is not really travelling like light. It effects the very material of Space-Time itself as opposed to traveling throught it. The problem is this view is contradictory to gravity behaving like a wave or having energy - in my understanding anyway. I’m starting to feel like I may be way off.
“Gravitational potential energy” seems to me like it means: To make Space-time explode to the dimensions it did took energy. This energy is stored in space-time and when it interacts with matter it responds by releasing some of this enegy in what we percieve as gravity. Correct or way off base?
If it is correct, I still don’t understand how come the following makes sense: Energy is used to create matter, and also to create and shape space time, but the two of these energies combined equal zero. Therefore, the universe could come from nothing because it is nothing.
When does the energy become nothing? A theory that hopes to explain “Why there is something instead of nothing” by stating “There really is nothing”, must show that there is nothing. I just can’t see how he the energy in gravity plus the energy in matter equals zero in any meaningful way.
What am I missing/screwing up? I realize this isn’t a college physics class, but it is a form of ignorance that I have, so all of your help is appreciated.
Is there a resolution to this “speed of gravity” issue? Can gravity move like a wave? Does it contain energy? Is there such a thing as a graviton? Is it instantaneous or does it have a speed? Is the speed fater than light? Do we even know? What would it take, experiment wise, to figure it out?
(Doing my part)