The force of gravity can become an insurmountable obstacle for extraterrestrial intelligence. Perhaps that is why there have been no guests from other galaxies on Earth until now.
The larger the planet, the greater its surface gravity and the mass of objects on it. For example, on a planet whose radius is twice that of the Earth, the mass of any object on its surface will be approximately 10 times greater. This contributes to the formation of the dense atmosphere necessary for the origin of life - but at the same time, it can literally nail an advanced civilization to the ground.
Take, for example, the planet Kepler-20b, whose radius is 1.9 times larger than Earth's, and its mass is almost 10 times. To launch a Hubble-type telescope from such a planet, which weighs 11 tons, requires more than 100,000 tons of fuel. The size of the fuel tank, which will fit such a sea of fuel, is difficult to imagine. A civilization that could appear on a planet of this size would probably have to forget about interplanetary travel.
The hypothesis that aliens simply cannot fly into space was put forward by the German astronomer Michael Hippke. He published a corresponding article in Popular Physics magazine. According to the scientist, space travel on chemical fuel is simply impossible for the inhabitants of planets with a mass of 10 or more times the Earth's mass. A way out of the situation can be nuclear-fueled rockets, or space elevators built from materials unknown to earthlings.