I believe there's other life in the universe, the universe is vast and rapidly expanding, new galaxies and planetary systems are still being created.
For life to exist the only thing needed is energy. On earth it comes from many sources, animals eat and drink, plants absorb sunlight and water and nutrients from the soil. In the Mariana Trench (the deepest part of the oceans) there are entire biospheres with alien-like animals that live without any sunlight at all, with the bottom of the food chain being little bacterias that consume sulfurous particles that come from steam vents in the ocean floor , 7 miles below sea level . There is evidence that similar alien-like biospheres exist on the south pole in Lake Vostok in Antarctica. So basically life on earth boils down to the precarious distance that we maintain from our sun that allows water to exist largely in liquid form, while also cycling through to gas and back. On Titan, Saturns largest moon, there is a liquid/gas cycle of methane, exactly like the liquid/gas cycle of water on earth, which suggests that just as life on earth is H2O based, life on titan could be CH4 based... and the same could work for many other elements and other moons and planets.
Also, as far as signs of intelligent life goes, as early as the late 70s scientists picked up strong radio wave signals in seemingly empty areas of space for around 30 seconds, that could not have been earth-originated since their frequencies were internationally banned for usage. so... u could conclude that since there is no planet in that spot, the signal had to have originated from a foreign body... such as a spaceship? : D
and again in 2003 SETI found even stronger signals in other "empty" areas in space, but the weird thing about it was that the frequency was one that hydrogen could absorb... which basically meant the radio signal could be transmitted across vast distances in space ... alien communication? : D
._. anyway... u should google SETI , they found tons of cool stuff ;blah;