猫是上楼还是下楼？答案揭晓

On Thursday, a picture of a cat walking on a set of stairs started to go viral. The original post asked readers if the cat was walking up or down the stairs.
4月9日，一张猫咪走楼梯的烧脑神图掀起讨论热潮。发布这张照片的原帖问道：这只猫到底是上楼还是下楼？

The story has since exploded and no one online can agree if the cat is running up or down. Commenters in both camps keep citing architectural and biological reasons for their conclusion.
随后，这个帖子被疯狂转载，这只猫到底是上楼还是下楼，网上没人能取得一致意见。两大阵营纷纷引用建筑学和生物学知识，不断为他们的结论寻找依据。

But it's obvious that the cat is going down the stairs.
但显而易见，这只猫是在下楼。

First, look at the architecture of the stairwell. The nose of the stair treads is overhanging the riser, which has a pebbled texture.
先来看看楼梯的建造结构。楼梯梯面的收边条伸出了鹅卵石材质的梯级竖板。

This is what the textured rise and stair nose might look like in real life:
下图或许可以还原梯级竖板和楼梯收边条在现实中的模样：

Plus, if you look closely, there's even a slight shadow under the overhanging nose of the stair treads. These shadows would only be visible if the cat was going down the stairs towards the viewer who is looking upstairs. The light coming from the upstairs landing is causing the shadow of the tread to fall on the riser:
另外，如果仔细观察，你甚至还能在伸出梯面的收边条下方看到浅浅的阴影。只有当这只猫正在下楼，走向看向楼梯上方的观察者时，阴影才有可能出现。光线从上一级平台照射下来，在梯级竖板上投射下梯面的阴影。

One Redditor suggested that what we're seeing are stair grips — not a stair nose — to keep people from slipping. But that would mean the stair grip would be ever-so-slightly raised (we know this because of the shadows), which would be extremely dangerous — people (and cats) would be tripping all the time.
社交新闻站点Reddit上的一名用户认为，我们看到的不是收边条，而是梯面上的防滑条，是为防止人们滑倒而设计。但这就意味着这些防滑条必须具有一定高度（从阴影来看），如此一来，这个楼梯就会变得极其危险——人（和猫）都会常常被绊倒。

Then there's this comment from Business Insider reader fred-sof: "The cemented in brick/stone in the side walls are placed in and on top of the step landings, they are the light grey brick shape items in the side walls."
商业新闻网站Business Insider用户fred-sof则评论道："侧边墙上用砖块或石块砌成的水泥块一般位于楼梯平台内部或上方，就是侧边墙上那些浅灰色砖块形状的东西。"

What he means is that bricks or stones are typically placed on top of step treads to build up the wall surrounding the stairs. Here's what that looks like in real life:
他的意思是，砖块或石块通常会位于梯面上方，用来搭建楼梯侧面的墙体。下图就是现实生活中的样子：

Finally, numerous commenters on Reddit insist that this is simply what a cat looks like when it's going down the stairs — tail up for balance, eyes focused on the ground, and taking the stairs step by step.
最后，Reddit上的众多评论坚持认为，这张照片完全就是一只猫下楼时的样子——尾巴上翘保持平衡，眼睛注视地面，一步一步走下楼梯。

"When my cat goes up stairs, he kind of hops up them," said Redditor ktphoenix. "Front paws first, then back ones, and on up. It's only when he's coming back down that he actually walks one paw at a time. That and the position of the ledge makes me pretty sure it's down."
"我家的猫上楼的时候基本是跳上去的。"Reddit用户ktphoenix说，"前爪先着地，然后才是后爪。只有在他下楼的时候才双爪交替走下来。从这一点，以及楼梯突起部分来看，我很肯定这只猫是在下楼。"

Obviously people can see it both ways, but you're only correct if you say the cat is going downstairs.
当然，每件事都会引起不同的观点。但只有当你说这只猫正在下楼时，你才是对的。

Vocabulary:

stair tread: 楼梯踏板

texture: 质地；纹理

stair nose: 梯面的收边条

stair grip: 梯面上的防滑条

（译者：清欢君 编辑：陈丹妮）