Pardon me for posting, but I thought that one of the more physic-minded dopers here might be able to help me out with an unusual question…
While musing over the subject of “Crossovers” in fiction, especially crossovers where characters from one fictional Universe or Diamention travel into another, I was left wondering…what would happen to our universe if extra mass and/or energy was added from an outside source?* Would anything happen? Nothing at all? Or does the question go against the laws of physics so much that it would be unanswerable? I seem to recall that the Star Trek novel “Dark Mirror” mentioned some sort of gravitational effects happening if too much mass was delivered to the “Destination” universe, but I don’t have a copy on hand to check.
Well, thanks for your patience,
Ranchoth
(Lord of needlessly wordy and bizarre questions. Hail to the king)
*And yes, I know that would violate the first law of Thermodynamics. But this would be an extraordinary case. Though I imagine one could argue around the question by saying that the Universes would have to be connected within a larger “Multiverse,” and you’d just be moving mass from one part of the Multiverse to another. But I digress.
I believe that you are asking “What would happen if we added mass to our universe as it is at this moment?”
Well:
It would depend on how we added it. Would you want stars/solar systems/galaxies popping out of nowhere? Flood the universe with particles?
Ultimately, the universe would only get a bit heavier. There would be changes to the Hubble constant, but it would take a positively huge amount of mass to significantly change the fate of the universe from an open to a closed universe.
How much mass? Added where? How dense is it? What is the method of addition – for instance, if a giant arm popped into existance over the earth and scattered gold dust over us, I imagine a lot of religious beliefs would change.
Also, since we don’t know just what the universe “weighs”, how would we know that it gained mass, unless there were some tremendous observable phenomena associated with it. And tremendous observable phenomona on a universal scale would tend to be very dangerous to the observers, I would think.
50,000 tons, contained in an area of 800’ x 100’ x 30’. Or: roughly the mass and density of one of the (fully loaded) ships of the U.S. Maritime Prepositioning Force. Does that help?
And thanks for the input, all! I appreciate it.
Ranchoth
I agree with yojimboguy. It’s a really freaking huge universe out there… what’s several thousand tons between friends? Heck, you could probably randomly add a galaxy or two without scewing things up too badly; I seriously doubt the universe would notice the USS Whatzawhozit.
And I’ll agree with g8rguy who agrees with yojimboguy. (just call me algernonguy)
You’d have to add a LOT of mass to have any impact. Eventually, if you add enough mass you’d have enough to slow the expansion of the universe, cause it to contract, ultimately ending up with the Big Crunch as it all collapses into a massive black hole.
I don’t recall off the top of my head how much mass “they” believe is missing to cause the reversal of the expansion of the universe… but whatever amount that is, is what you’d need to add.
A monopole gravitational wave would mean that a short time later (speed of light) an object at some distance would suddenly start feeling a gravitational attraction that wasn’t there before. Aside from confusing a bunch of physicists, I don’t think that this would have any major effect.
It would definitely confuse physicists, though. Unlike the usual quadrapole gravitational waves (the lowest-order type believed to be possible), a monopole wave would be fairly easy to detect, even by instruments not designed to detect gravitational waves. I imagine that it would register on most of the gravitometers used by oil companies and the military, for starters.
Quoth Algernon:
It’s worse than that… Current thinking has it that most of the mass of the Universe isn’t mass. That is to say, all the “stuff” that should be there, is, but some of it is pushing the Universe apart, rather than pulling it together. Not only would you have to overcome all the so-called “dark energy”, but the longer you wait, the harder it will become to do so. In any event, though, to make a difference to that, you’d need to add density to the Universe, not just mass, so you’d need an infinite number of ships materializing, evenly distributed through the Universe.
what if the gravititation monopole was pointed directly at france, and it sucked all the people and buildings of paris into a black hole and they vanish never to be seen again?
