Chuck Darwin<p>Gravitational waves produce a background hum across the whole universe |</p><p>The fabric of the universe is constantly rippling, according to astronomers who have discovered a background buzz of <a href="https://c.im/tags/gravitational" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>gravitational</span></a> <a href="https://c.im/tags/waves" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>waves</span></a>. These waves may be produced by <a href="https://c.im/tags/supermassive" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>supermassive</span></a> <a href="https://c.im/tags/black" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>black</span></a> <a href="https://c.im/tags/holes" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>holes</span></a> merging across the universe, but they might also have more exotic origins, such as leftover ripples in space-time created shortly after the <a href="https://c.im/tags/big" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>big</span></a> <a href="https://c.im/tags/bang" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>bang</span></a>. </p><p>Pinning down their true nature could tell us about how supermassive black holes grow and affect their host galaxies, or even about how the universe evolved in its first moments.</p><p>To find this mysterious hum, astronomers have been tracking rapidly rotating neutron stars called <a href="https://c.im/tags/pulsars" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>pulsars</span></a> that blast out light with extreme regularity. By looking at different pulsars across the Milky Way, astronomers can effectively use them as a galaxy-sized gravitational-wave <a href="https://c.im/tags/detector" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>detector</span></a> called a pulsar <a href="https://c.im/tags/timing" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>timing</span></a> <a href="https://c.im/tags/array" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>array</span></a>.</p><p>While individual gravitational waves, which are ripples in space-time created by massive objects colliding, have been seen regularly since the first detection in 2015, the object of this search is different. Those previous gravitational waves all have a <a href="https://c.im/tags/localised" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>localised</span></a> origin and rise and fall hundreds of times a second, but the newly-discovered signal is more like a gravitational wave <a href="https://c.im/tags/background" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>background</span></a> that would permeate the entire universe at much <a href="https://c.im/tags/lower" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>lower</span></a> <a href="https://c.im/tags/frequencies" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>frequencies</span></a>, similar in concept to the cosmic microwave background, which is radiation left over by the big bang and seen all over the universe today.</p><p><a href="https://www.newscientist.com/article/2380451-gravitational-waves-produce-a-background-hum-across-the-whole-universe/" rel="nofollow noopener noreferrer" target="_blank"><span class="invisible">https://www.</span><span class="ellipsis">newscientist.com/article/23804</span><span class="invisible">51-gravitational-waves-produce-a-background-hum-across-the-whole-universe/</span></a></p>