The light waves of some remote galaxies have not reached yet reached our system. Given the infinite vastness of the universe, there could as well be a ‘’Hello’’ message on way coming to us. Based on this idea, I think there are civilizations except for our galaxy and they may send or they may have already sent a ‘’Hello’’ message to us.
Our universe is so big to contain only one life form, humans, and not only our universe some say that there are other universes. So some people think that our universe is already so big for humans and there are theories for other universes too, so we might not be alone and I think like this too. For the beginning, light travels at approximately 300,000 km per second. Although it may sound very fast, the intergalactic distances are also very high. For example, our earth is in the Milky Way galaxy and the closest galaxy to the Milky Way galaxy is andromeda galaxy but the distance between them is 2.54 million light years. So if the distance between andromeda and milk way is this high think about the other galaxies. As humans, we see thing through the reflections of light but when the distance between light and the object increases the time that the reflection of light come to us increases as well and because of that we see the objects when the light was reflected. And signals also take some time to get here and some signals that we may find from other galaxies may extinct when we get it. Maybe that hello signal come already but we did not notice because of the technology of that time. Maybe it has already come to earth at the 1400s but we did not notice it because of the lack of technology. Even today our technology is barely enough for it. Today radio telescopes detect and amplify the radio waves from space to turn them into signals that astronomers can understand. And we hope to get a message from space by radio waves today.
In conclusion, I think our universe is so big to contain one life form and if we look at the distance and the speed of time I think we have a high chance to get a message from other galaxies. Because there might be hundreds of life forms and I think at least one of them could find a way to communicate with us.