Can humans survive in high oxygen?

Higher-than-normal oxygen levels aren’t as harmful to life, but there is an increased change of fire or explosion risk. With extremely high concentrations of oxygen in the air, humans can experience harmful side effects. Very high levels of oxygen cause oxidizing free radicals to form.

When did Earth’s atmosphere become breathable for humans?

About 500 million years ago
About 500 million years ago, the Earth, for the first time, attained an atmosphere that we would consider breathable.

Is time travel to the past possible?

A great many unusual things become possible in the Universe if negative mass/energy is real, abundant, and controllable, but traveling backwards in time might be the wildest one we’ve ever imagined. Owing to the oddities of both special and general relativity, time travel to the past might not be forbidden after all!

What would happen if you time travel for 82 years?

But back on Earth, 82 years would have passed. Everyone you know would have aged tremendously. This is the standard way time travel physically works: it takes you into the future, with the amount of travel forward in time dependent only on your motion through space.

Where would you go if you could travel back in time?

If I could travel back in time, I would go to back to Eastern African Swahili coast in the early 1400’s before the European colonisation began. There were a handful of larger city-states that had trade relations with Arabs and then small tribal villages spread out throughout the region.

What would happen if you lived for 82 years on Earth?

Due to time dilation and length contraction, you might reach your destination in only a year, and then come back in just another year. But back on Earth, 82 years would have passed. Everyone you know would have aged tremendously.