If an asteroid large enough to incinerate any and all living organisms were to hit Earth?

Question

A. Would any man-made structures be able to survive as proof of our existence?

B. How long would it take life to start again?

Answer 1

Wow.  Well, if there was enough sustained energy to cause all of the surface water to evaporate, it would be extremely unlikely for any surface structures to persist.  Things under ground may be able to survive.

No clear answer as to whether life, if totally and completely obliterated, would actually start up again or not.  However, there is life deep within the earth, so total obliteration of all life is highly unlikely, even under the extremely catastrophic conditions you describe.

Answer 2

OK, Let's Assume An Asteroid Was Sufficiently Large Enough To Burn All Life.

There Is Sulfur Based Life In The Deep Sea Around Hydrothermal Vents So The Asteroid Would Have To Have Enough Energy To Vaporize The Majority Of The Oceans.  Whew, That Would Be Hot.

There Are Some Very Stable Regions On The Planet Under The Surface.  Certain Salt Mines That The US Government Is Looking Into To Store Spent Uranium From Power Plants. They Might Survive And It's Probable That Other Countries Have Similar Structures.  There Are Also Hardened Nuclear Silos That Might Survive For Maybe A Million Years Or So.

The Problem Seems To Be That Such An Asteroid Would Likely Have To Blow The Planet Into Little Bits To Burn ALL Life, If It Could.

More Likely Is That The Planet Would Be Sufficiently Destroyed So That It Would Probably Be Knocked Out The Orbit It's Now In.

Should That Happen, Earth Would Be A Bunch Of Planetesimals, Small To Large Rocks Of Dust And Ice That Would More Than Likely Not Be Able To Hold A Suitable Atmosphere, Temperature And Gravity To Sustain Any Life Like Mammals Or Plants.

It's Possible That Some Bacteria Might Survive But Conditions Would Be Very Harsh And Likely Even Those Would Not Survive.

So, The Most Probable Scenario Is Such An Asteroid That Was Capable Of Burning All Life One Earth Would Instead Smash Earth Into Pieces.

So, Nothing We Make Would Survive (For Long) And No Life Would Survive And No Life Would Be Possible Because Conditions On Any Remaining Pieces Would Be Unable To Support Life.

Interesting Thought Question.  Scary, But A Fun Escape From Day To Day Drudgery.

Answer 3

Well if it was large enough to incinerate us, i doublt there would be much of a world left.

Answer 4

A Yes, a few.

B 3.6 billion years, the same time it took before.

I can't wait!

Answer 5

probably not

without water there is no life