Hawking说宇宙没有清晰的“大爆炸”的一声，你可以把时钟向后倒回到那些存在的最初时刻的边缘，但是问之前发生了什么，就象问你为什么到达北极点后可以一直向北走。时间，正如我们定义的那样，随着宇宙的收缩而失去意义。它永远不会变窄到一个点。但是没有人证明物理学是这样的。霍金提出了时空无边界条件的版本。当你接近起点时，时空被虚时间取代

Watch Stephen Hawking Explain What He Thinks Came Before the Big Bang

Watch Stephen Hawking explain what he thinks came before the ...

www.newsweek.com/what-watch-stephen-hawking-explain-what...

Hawking talks about no clear Big Bang and no boundary to space-time

Hawking talks about no clear Big Bang and no boundary to ...

• www.nextbigfuture.com  › Science

Hawking talks about no clear Big Bang and no boundary to ...

thetechnews.org/hawking-talks-about-no-clear-big...

Stephen Hawking thinks he knows what happened before the beginning of time

Stephen Hawking thinks he knows what happened before the ...

www.popsci.com/stephen-hawking-neil-degrasse...