No, it is not true that one hour in space is equivalent to 7 years on Earth. This claim is a common misconception that stems from a misinterpretation of the theory of relativity.
According to Einstein's theory of relativity, time dilation occurs when an object is in motion relative to another object or in the presence of a gravitational field. Time dilation means that the rate at which time passes for an object depends on its relative motion or the strength of the gravitational field it is experiencing.
For objects moving at speeds close to the speed of light or in the vicinity of a massive object like a black hole, significant time dilation can occur. However, the effect is not as extreme as the claim that one hour in space is equivalent to 7 years on Earth.
In practice, the time dilation experienced by astronauts in space is relatively small. For example, astronauts aboard the International Space Station (ISS), which orbits the Earth at a speed of about 28,000 kilometers per hour (17,500 miles per hour), experience a slightly slower passage of time compared to observers on Earth. However, this difference is on the order of microseconds (millionths of a second) over the course of six months aboard the ISS.
So while time dilation is a real phenomenon predicted by Einstein's theory of relativity, the claim that one hour in space is equivalent to 7 years on Earth is a significant exaggeration and not supported by scientific evidence.