Do you feel lonely to know that you are the only civilization living in this universe? We have searching for ET for hundreds of years, but “where is everybody”? In today’s world, we are looking for aliens with electro-magnetic spectrum. However, does it make sense to look for ET with such method? Some scholars made an analogy which told us it is like using pre-technology such as smoke and drum to make modern people get you what you are saying. The chance of making them understand our voice is rare, because it is unlikely that a faring civilization would use electro-magnetic spectrum to communicate if they know the speed of light is limited, and it is going to many years to receive it. Nobody would have the time.

Such statement is very convincing and speculative. However, it makes us to think which direction we should make our next step and also to consider how the technology might play out elsewhere in the universe.

The method we are using right now is mainly limited by the speed of light. We know that our radio signals have been traveling through universe for about 80 years, which would means that only civilization within 80 light years from us would received that signal or have the opportunity to receive our signals, and those who are within 40 light years would send something back to us. However, we still haven’t got anything back yet. So far, we can only answer Fermi’s question of “where is everyone” by saying they are not within 40 light years. Probably, our project looking for aliens is wrongheaded over all.

What else could we choose? In term of what could reach us, there are 4 categories.

1. electromagnetic signals(What we are now using)
2. Gravitational wave signals, but we need a equipment that is sensitive enough to detect such distinct signal of intelligent life.
3.  macroscopic space probe. (Unlikely to happen, for it is time consuming)
4. Neutrino signals.

The most likely project is to spend money on the last option. It is possible to achieve, since nuclear power or fusion power is proven to be efficient. It has very specific neutrino signatured  as a by-product of fusion, which cannot be produced by natural process. If we find a way to detect that particle we can easily find civilization that is able to use fusion power. As we continually develop our technology and our knowledge of universe, we won’t be lonely for lon perhaps even someday soon, we will find the surprise reserved for us: that we are not alone in this world.