平行宇宙里到底有没有生命？

According to the current dominant theory, if there are other universes out there, they're not likely to have life. But now an international team of researchers has demonstrated that the Multiverse is more hospitable than we thought.

根据目前的主流学说，即便存在平行宇宙，里面也不太可能存在生命。但最近，一支国际研究团队证明平行宇宙比我们想象的更宜居。

The Multiverse hypothesis - wherein our observable Universe is just one of many universes - is a proposed explanation for the not-large-enough amount of dark energy in the empty space in our Universe.We don't really know what dark energy is - it's the name we give to the force that drives the expansion of our Universe, which, contrary to pretty much everything else we observe, accelerates over time instead of slowing down.It constitutes around 70 percent of the Universe - and that's the problem. Because current theories about the origin of the Universe predict that there should be much more dark energy than that.But they also predict that if there were more dark energy than our currently calculable low amount, the Universe would be expanding so fast that matter would dilute before it could form into stars, and planets, and galaxies.Which means we wouldn't exist.

根据“平行宇宙”假说，除我们的可观测宇宙外，还存在许多其它宇宙。该假说可以解释宇宙里暗能量不足的现象。什么是暗能量?谁也不清楚。它指的是推动宇宙加速膨胀的力，占宇宙的70%。问题来了：从有关宇宙起源的现有学说推测，暗能量应该远远超过这个数量;但如果暗能量远多于当前计算量，那么宇宙的膨胀速度会快到物质无法形成恒星、行星、星系等——也就是说，我们将不复存在。

This is where the Multiverse comes in. It proposes that there are many universes outside our own (and there are a number of models for what this might look like), each with a different proportion of dark energy, and ours is one that just happened to have a smaller amount so that life could form.

于是，“平行宇宙”假说诞生了。它提出，在我们的宇宙之外，还存在许多个平行宇宙，每个宇宙具有不同的暗能量比例，而我们的宇宙恰好拥有较低比例的暗能量，因此能够形成生命。这个解释非常优雅。

It's a very neat explanation - some scientists argue, a little too neat, involving circular reasoning, unbacked by any observational evidence, and untestable.

不过，一些科学家认为，它有点太过优雅了，而且涉及“循环论证”，既缺乏观测证据、也无法进行检验。

But we can run tests on our own Universe - and that's exactly what the researchers have done.

不过，我们可以检验我们的宇宙呀。

Led by physicist Jaime Salcido of Durham University in the UK, the team created enormous simulations of the Universe, tweaking the amount of dark energy using the Evolution and Assembly of GaLaxies and their Environments (EAGLE) project, one of the most realistic simulations of our Universe.And they found that increasing - or decreasing - the amount of dark energy in our Universe, even up to a few hundred times the amount we observed, would only have a modest impact on the formation of stars and planets.

这回，在英国杜伦大学的物理学家Jaime Salcido的带领下，研究团队创建了庞大的宇宙模拟项目，并调整暗能量的数量。研究结果非常有趣。他们发现，增加或减少我们宇宙的暗能量数量(即便增加几百倍)对恒星和行星的形成只有中等程度的影响。

"For many physicists, the unexplained but seemingly special amount of dark energy in our Universe is a frustrating puzzle," Salcido said."Our simulations show that even if there was much more dark energy or even very little in the Universe then it would only have a minimal effect on star and planet formation, raising the prospect that life could exist throughout the Multiverse."

许多物理学家认为，我们宇宙的暗能量数量非常特殊，恰好能够形成生命，这种巧合是个谜团。但这项新研究表明，增加或减少暗能量对恒星和行星的形成没有太大影响。也就是说，平行宇宙里也可能存在生命。

It also raises another issue: If we don't need the Multiverse to explain our existence, is it still a plausible theory?

不过，现在又有另一个问题了：如果我们不需要平行宇宙来解释我们的存在，那么它还算是一个合理的假说吗?

According to the researchers, they haven't ruled it out. Instead, they believe that the answer to the dark energy conundrum lays in something we haven't figured out yet.

研究人员表示，他们并不排除这种可能性。他们认为，暗能量之谜的答案可能藏在人类尚未发现的物理学新定律里。