 Many people have cited various reasons why time travel is or is not possible, how ever they seem to have missed one important point. The first law of thermodynamics states that matter can neither be created or destroyed. This means, then, that at any one moment the amount of matter in the universe is exactly the same. Time travel, how ever, would change that. Suppose one were to make a "Time machine", and place in it, as an example, some cash. Now, this person could send the machine, with the money backwards in time to her or him self, who was waiting for it in the past, having previously planned this enterprise. Then, he or she would earn the money as before in what was, to the past, the future, but to the present the past, and find her or him self with two lots of money; one from the future, and one from the past. If she kept doing this, and waited long enough before filling the time machine with money, he or she could accumiate vast quantities of money in the interim.
 At a point between the time to which one would send any object, and the time from which one could send it, one might amass a theoretically infinite amount of objects. That would be impossible, especially if these objects contained energy (such as a battery). This would mean that an infinite amount of energy could be created "free", and this, as all good scientists know, is impossible.
 At a point between the time to which one would send any object, and the time from which one could send it, one might amass a theoretically infinite amount of objects. That would be impossible, especially if these objects contained energy (such as a battery). This would mean that an infinite amount of energy could be created "free", and this, as all good scientists know, is impossible.
