Negative energy, as a term, is a slight misnomer. It is more accurate to say negatively charged energy.
Energy can carry any kind of charge, but will not become charged of its own volition, simply because it makes no decisions about anything for itself. The charge usually comes from a person, or persons, with some sort of intent about something or other. A very common, and negative, example of such an intent could be anger or jealousy. This is then usually projected towards someone else, for whatever reason; and this would arrive with the intended victim, who often begins to experience unfortunate events in his or her life where they may find themselves getting hurt, or into trouble of some sort. This example is, of course, over simplified and serves simply as an illustration. It is more complex than that.
The amount of anger necessary from one person to have an immediate effect on another, with only a single effort, would have to be colossal. It is possible however, but not probable. If the average citizen had such a one-time capability, I doubt there would be anyone left alive on earth. For one person to have such an effect on another, would probably take a long time – perhaps months, of effort. This can be seen in the snowballing result if someone lives in an environment of, say, family strife and unhappiness and ill-wishing that goes to the limits of endurance, and cannot be brought to resolution. This would be an example of a long term build-up of negativity. Where negatively charged energy becomes a more all encompassing menace, is when entire communities, or large groups of likeminded people, contribute to the mindset. Then it is like existing in a sea of this particular sentiment where, slowly over time, everyone becomes affected to the minimum level, which also becomes the optimum level, which often brings about the regrettable consequence, for example, of riots or street violence. A common example of this kind of collective and negative influence with many participants is what we have aptly termed road rage. A sea of negatively charged energy determines the mood of all drivers on the hi-ways and byways; although some can control and withstand it better than others. Those who cannot often become so affected that they live with it all the time and become known as moody and unpleasant people, who may think of themselves as regular and ordinary, but are so often given to episodes of rage that it becomes difficult for others to get on with them.
Most people are also prone to stress, which is another of these oceans of negatively charged energy. As we are all too familiar with stress, it is clear that it does not necessarily originate on the hi-ways and byways alone, but in many other circumstances as well.
There is an ever increasing list of spin-offs of this nature that are fed by each other in varying degrees, and creates, in many ways, the mood of all of society around us. To me, it is amazing that people everywhere seem to accept this ever growing condition as normal, and they do not appear to be unduly bothered by it. Humans are truly a marvel for the things they can get used to.