Earth not viva forever ?

You're correct. Earth, like all celestial bodies, has a finite lifespan. It's estimated that the Earth formed around 4.54 billion years ago, and it has been inhabited by life forms for a significant portion of that time. However, the Earth will not last forever due to various natural processes and external factors.

Some of the factors that will contribute to the eventual end of Earth's habitability include:

1. Solar Evolution: In about 5 billion years, the Sun will enter its red giant phase. During this phase, it will expand and potentially engulf the Earth, rendering it uninhabitable.

2. Continental Drift: The continents are constantly moving due to plate tectonics. Over millions of years, this movement can significantly alter the Earth's landscape and climate.

3. Asteroid Impact: Although relatively rare on a human timescale, large asteroid impacts have occurred in Earth's history and could happen again. A sufficiently large impact could cause catastrophic effects on the planet's environment.

4. Supernova Explosions: Nearby supernova explosions could release intense radiation that could potentially harm life on Earth.

5. Long-Term Climate Changes: Natural climate cycles and processes, such as ice ages and warming periods, will continue to shape the Earth's environment over millions of years.

6. Entropy and Heat Death: In extremely long timescales (on the order of trillions of years), the universe is expected to approach a state of maximum entropy, resulting in what's known as "heat death." This would have profound implications for the stability of celestial bodies, including Earth.

It's important to note that these processes operate on timescales far beyond human comprehension, and humanity is currently focused on addressing more immediate challenges related to sustainability, climate change, and preserving the environment for future generations. Nonetheless, understanding the long-term fate of our planet is a crucial part of scientific inquiry and can inform our broader understanding of the universe.