Question

how can be fly in sky without anything ?

Answer 1

Answer:

Never

No chance..

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Answer 2

Answer:

And now, scientists have determined that we never will: it is mathematically impossible for humans to fly like birds. A bird can fly because its wingspan and the wing muscle strength are in balance with its body size. ... Thus, an average adult male human would need a wingspan of at least 6.7 meters to fly.