It is important to remember that, relative to the known universe, Earth is very small.
The universe is vaster than can be comprehended, and possibly infinite in spatial extent.
Distances and sizes are readily available in common reference materials.
The quantity of energy accessible in the universe is also vast beyond comprehension.
A Kardashev scale value of about 1.0 would be the limit that human civilization could attain without becoming spacefaring, for beyond that level, regardless of the energy source, the waste heat from energy consumption would cause unmanageable ecological problems 13.
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