What's it called when you know something before it happens?
Premonition or precognition. If you dream something that then comes true, it's still a premonition, or just plain chance. There is usually a "pre- determined recognition" of the possibility of something happening, that triggers a premonition. Pre- cognition, for short. Understanding, before the event. Usually, it's an assumption. If "it" happens, you can say, "I knew this was going to happen!", but if it doesn't happen, you tend to forget you thought it would.
Why do I keep hoping for something that will never happen?
Same reason people keep buying lottery tickets. Hope springs eternal. On the other hand, it sounds like perhaps you are in love with someone who can't, doesn't or shouldn't return your love. It is hard to move on from that. You are obviously aware of what is going on. Think about what advice you would give to someone else in your position and then do it. Don't be like Alice in Wonderland, who said "I give myself very good advice, but I very seldom follow it." You KNOW what you should do. Remember the consequences of not doing the right thing. Good Luck!
What does it mean when I know something is going to happen before it happens?
In phsycology they call the ability to forsee future events ESP, extra sensory perception, I call it the the ability to prophesy, Jesus talked about it in the bible. In Acts 2;16 &17 the Apostle Peter said: 16 But this is that which was spoken by the prophet Joel, 17And it shall come to pass in the last days, saith God, I will pour out of my Spirit upon all flesh: and your sons and daughters shall prophesy, and your young men see visions, and your old men shall dream dreams: I think it's a gift from God & can be a good thing if you use it wisely.
How do dogs tell/show you if something bad is going to happen?
Its really you that has to be in tuned... If you know your dog well enough, you'll know when they are acting strange. If you cant find a cause for it, then its on you to start thinking about something he/she "senses from afar." Normal everyday doggy things that your pet does are not warnings... but things he/she has never done before is a tell tale sign. Also, probably they may become somewhat obsessed at getting your attention.... But the biggest one is probably the "alarming bark"... if you know your dog well enough, you can differentiate between different barks and you'll know something's up. EDIT- chzbrgr, while they aren't "physic", they are sometimes an advanced warning system. Take for eg. the 2004 Tsunamis, reports of dogs, elephants, and zoo animals acting extremely bizarre hours before the waters hit. My malamute knows when a big storm is coming, he'll bark at dark clouds on the horizon....
Can cats tell if something bad is going to happen?
well, I don't want to freak you out but yes, cats are usually pretty good at predicting things for example, this cat was able to predict death for elderly folks in a nursing home: http://news.bbc.co.uk/2/hi/americas/6917113.stm however, that is no reason to freak out your cat may be predicting something completely different such as a storm coming your way, or a big fight between your parents, or something of the like... if I were you, I would stay calm yet, I would also stay awake and watch your sister for a little while...just to be on the safe side (I'm sure your sister will be fine, but if you're worried then you won't be able to sleep anyway, so you might as well watch out for her and put your mind at ease) try to relax, pull out a good book or watch a movie with your sister everything will be fine, but to put your mind at ease you should stay awake for awhile and keep an eye out for her
Can animals really sense when something bad is going to happen to their owner?
Dogs have far better senses of smell and hearing than we do. They can certainly smell or hear something coming before we can and make a noise to alert their owner or warn whatever it is off. Mostly, dogs actually react to their owner. We all give out little signals that we're barely aware of, about whether we're scared or nervous or angry - dogs sense these and immediately assume that if their owner or 'leader' is afraid of something or on guard, they have reason to be the same. Some people also say that cats and dogs can detect illness; I think scientists and animal experts believe that it's because they can smell biochemical changes in the body caused by the enzymes and chemicals emitted as organs begin to shut down or disease begins to take over. If animals had a sixth sense about something impending, surely you'd never see a dog, cat or other animal hit by a car, and animals would rarely be involved in accidents; they'd know to get out of the way faster.