物理學(xué)家說，沙丘之間相互作用，相互“交流”

物理學(xué)家說，沙丘之間相互作用，相互“交流”

Whether on land or underwater, sand dunes usually appear in large groups. But even when these natural formations are in close touch with their neighbours, they still need their personal space from time to time.

無論是在陸地上還是在水下，沙丘總是成群出現(xiàn)。但即使這些自然形態(tài)與它們的鄰居有密切的聯(lián)系，它們?nèi)匀徊粫r(shí)地需要自己的私人空間。

When two identical dunes migrate over long distances, physicists have found these structures will unexpectedly change their pace so they end up evenly spread out, prompting speculation about how these mounds of sand can 'communicate'.

當(dāng)兩個(gè)相同的沙丘長(zhǎng)距離移動(dòng)時(shí)，物理學(xué)家發(fā)現(xiàn)這些結(jié)構(gòu)會(huì)出人意料地改變它們的速度，所以它們最終會(huì)均勻地分散開來，這引發(fā)了人們對(duì)這些沙丘如何“交流”的猜測(cè)。

They're definitely communicating, physicist Nathalie Vriend from Cambridge University said in an interview with The Washington Post.

來自劍橋大學(xué)的物理學(xué)家Nathalie Vriend在接受《華盛頓郵報(bào)》的采訪時(shí)說:“它們確實(shí)在交流。”

Obviously, sand dunes can't speak to each other. But the researchers argue that the influence dunes have on the forces moving them - such as wind or water - changes how those forces affect other dunes around them, making these physical structures 'communicate' their position.

很明顯，沙丘之間不能相互交流。但研究人員認(rèn)為，沙丘對(duì)風(fēng)或水等移動(dòng)它們的力量的影響改變了這些力量對(duì)周圍其他沙丘的影響，使這些物理結(jié)構(gòu)“傳達(dá)”了它們的位置。

This is contrary to what many theoretical models have supposed about dune migration, which occurs so slowly and across such great distances that it's extremely difficult to study.

這與許多理論模型對(duì)沙丘遷移的假設(shè)相反，沙丘遷移發(fā)生得如此緩慢，跨越如此遙遠(yuǎn)的距離，以至于很難進(jìn)行研究。

Generally, these structures are seen as self-propelling autonomous agents that can sometimes collide and consume each other, but not necessarily collaborate.

一般來說，這些結(jié)構(gòu)被看作是自我推動(dòng)的自主主體，它們有時(shí)會(huì)相互碰撞和消耗，但不一定會(huì)相互協(xié)作。

We've discovered physics that hasn't been part of the model before, says Vriend.

Vriend說:“我們已經(jīng)發(fā)現(xiàn)了以前模型中沒有的物理學(xué)。”

By creating a rotating water-filled channel, the team was able to keep two identical dunes swirling in circles for hours at a time. Rather than moving at the same initial pace, the dune in front initially sped up.

通過創(chuàng)建一個(gè)旋轉(zhuǎn)的充滿水的通道，該團(tuán)隊(duì)能夠讓兩個(gè)相同的沙丘一次旋轉(zhuǎn)幾個(gè)小時(shí)。前面的沙丘一開始并沒有以同樣的速度移動(dòng)，而是加速了。

Once it had travelled 180 degrees to reach the opposite side of the circular channel, the leading dune slowed down to the same pace as the other.

當(dāng)它轉(zhuǎn)了180度到達(dá)環(huán)形水道的另一邊時(shí)，領(lǐng)頭的沙丘就放慢了速度。

The flow structure behind the front dune is like a wake behind a boat, explains Vriend, "and affects the properties of the next dune."

“前面沙丘后面的流動(dòng)結(jié)構(gòu)就像船后面的尾流，”Vriend解釋說，“并影響下一個(gè)沙丘的性質(zhì)。”

By creating turbulence in the water flow, the first dune pushes the one behind it. In other words, the leading structure is interacting with and repelling its downstream neighbour - 'communicating' through its wake, and giving up very little of its own mass in the process.

通過在水流中制造湍流，第一個(gè)沙丘推動(dòng)后面的沙丘。換句話說，主導(dǎo)的結(jié)構(gòu)與下游的鄰居相互作用并相互排斥——通過尾流“交流”，在這個(gè)過程中只放棄了很少的一部分。

This repulsion for nearby sand dunes has been observed in satellite images before, but the forces behind it have never been understood.

這種對(duì)附近沙丘的排斥在以前的衛(wèi)星圖像中已經(jīng)被觀察到，但其背后的力量卻從未被了解。

We conclude therefore that it is plausible that the structure of natural underwater dune fields is controlled and stabilised by the same dune-dune repulsion mechanism observed in this work, the authors write.

作者寫道:“因此，我們得出的結(jié)論是，自然水下沙丘場(chǎng)的結(jié)構(gòu)似乎是由在這項(xiàng)研究中觀察到的相同的沙丘-沙丘推斥機(jī)制控制和穩(wěn)定的。”

If this activity also exists on land, it could be incredibly important for climate change preparation. Over the years, global warming has increased dune movement in certain parts of the world, including in the US, Africa, and Antarctica.

如果這種活動(dòng)也存在于陸地上，它可能對(duì)氣候變化的準(zhǔn)備工作非常重要。多年來，全球變暖已經(jīng)增加了世界某些地區(qū)的沙丘移動(dòng)，包括美國(guó)、非洲和南極洲。

Figuring out where these massive structures of sand are headed - and how they travel - could allow us to prepare farms, roads, infrastructure and livelihoods for the oncoming collision.

弄清楚這些巨大的沙子結(jié)構(gòu)將走向何方——以及它們?nèi)绾我苿?dòng)——可以讓我們?yōu)榧磳⒌絹淼呐鲎矞?zhǔn)備好農(nóng)場(chǎng)、道路、基礎(chǔ)設(shè)施和生計(jì)。

The study was published in Physical Review Letters.

這項(xiàng)研究發(fā)表在《物理評(píng)論快報(bào)》上。