What is the cosmic web?
When you zoom far enough out, our universe has a very unusual structure.
- Composed of massive filaments of galaxies separated by giant voids, the cosmic web is the name astronomers give to the structure of our universe.
- Why does our universe have this peculiar, web-like structure?
- The answer lies in processes that took place in the first few hundred thousands years after the Big Bang.
Looking up at the night sky, it seems as though the stars and galaxies are spread out in a more or less random fashion. This, however, isn't really the case. The universe isn't a random jumble of objects; it has a structure composed of galaxies and gas. Cosmologists call this structure the cosmic web.
The cosmic web is composed of interconnecting filaments of clustered galaxies and gases stretched out across the universe and separated by giant voids. The largest of these filaments that we have found to date is the Hercules–Corona Borealis Great Wall, which is a staggering 10 billion light years long and contains several billion galaxies. As for the voids, the largest is the Keenan, Barger, and Cowie (KBC) void, which has a diameter of 2 billion light years. Within a segment of the spherical KBC void lies the Milky Way galaxy and our planet.
Altogether, these features give the universe a foamy appearance. However, once you zoom out far enough, this pattern disappears, and the universe appears to be a homogeneous chunk of galaxies. Astronomers have a delightful name for this sudden homogeneity — the End of Greatness. At smaller scales, however, we can see that the universe does indeed have a rather magnificent structure. This begs the question: How did this structure come to be?
It starts with a bang
Space itself has fluctuating energy levels. Incredibly small pairs of particles and anti-particles are spontaneously coming into existence and annihilating each other. This "boiling" of space was happening in the early universe as well. Normally, these particle pairs destroy each other, but the rapid expansion of the early universe prevented that from happening. As space expanded, so too did these fluctuations, causing discrepancies in the density of the universe.
A visualization of quantum fluctuations.
Because matter attracts matter through gravity, these discrepancies explain why matter clumped together in some places and not others. But this doesn't fully explain the structure of the cosmic web. After the inflationary period (roughly, 10-32 seconds after the Big Bang), the universe was full of primordial plasma clumping together due to the aforementioned discrepancies. As this matter clumped together, it created pressure that counteracted gravity, creating ripples akin to a sound wave in the matter of the universe. Physicists call these ripples baryon acoustic oscillations.
Simply put, these ripples are the product of regular matter and dark matter. Dark matter only interacts with other things through gravity, so the pressure that causes these ripples doesn't affect it — it stays at the center of ripple, not moving. Regular matter, however, is pushed out. A little under 400,000 years after the Big Bang, the universe has cooled enough such that the pressure pushing the matter out is released through a process called photon decoupling.
An artist's illustration of the rings formed by baryon acoustic oscillations.
Zosia Rostomian, Lawrence Berkeley National Laboratory
As a result, the matter is locked into place. Some regular matter finds its way back to the center of the ripple due to the gravitational attraction of the dark matter. The result is a bullseye: Matter in the middle and matter in a ring around the middle. Because of this, physicists know that you're more likely to find a galaxy 500 million light years away from another galaxy than you are to find one 400 or 600 million light years away. Simply put, galaxies tend to be found at the outer rings of these cosmic bullseyes.
Altogether, these processes produced the gigantic web of stuff that compose our universe. Of course, there are many other processes that go into producing the cosmic web, but these fall outside the scope of this article. For those of you interested in observing what this structure would look like, you're in luck: astronomer Bruno Coutinho and colleagues developed an interactive, 3D visualization of the universe's structure, which you can access here.
The Cosmic Web, or: What does the universe look like at a VERY large scale?The Millennium Simulation featured in this clip was run in 2005 by the Virgo Consortium, an international group of astrophysicists from Germany, the United K...
Famous physicists like Richard Feynman think 137 holds the answers to the Universe.
- The fine structure constant has mystified scientists since the 1800s.
- The number 1/137 might hold the clues to the Grand Unified Theory.
- Relativity, electromagnetism and quantum mechanics are unified by the number.
Younger Americans support expanding the Supreme Court and serious political reforms, says new poll.
- Americans under 40 largely favor major political reforms, finds a new survey.
- The poll revealed that most would want to expand the Supreme Court, impose terms limits, and make it easier to vote.
- Millennials are more liberal and reform-centered than Generation Z.
A 2020 study published in the journal of Psychological Science explores the idea that fake news can actually help you remember real facts better.
- In 2019, researchers at Stanford Engineering analyzed the spread of fake news as if it were a strain of Ebola. They adapted a model for understanding diseases that can infect a person more than once to better understand how fake news spreads and gains traction.
- A new study published in 2020 explores the idea that fake news can actually help you remember real facts better.
- "These findings demonstrate one situation in which misinformation reminders can diminish the negative effects of fake-news exposure in the short term," researchers on the project explained.
Previous studies on misinformation have already paved the way to a better understanding<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDU1NzQ4NC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYxNjE2Mjg1Nn0.hs_xHktN1KXUDVoWpHIVBI2sMJy6aRK6tvBVFkqmYjk/img.jpg?width=1245&coordinates=0%2C800%2C0%2C823&height=700" id="fc135" class="rm-shortcode" data-rm-shortcode-id="246bb1920c0f40ccb15e123914de1ab1" data-rm-shortcode-name="rebelmouse-image" alt="fake news concept of misinformation and fake news in the media" />
How does misinformation spread?
Credit: Visual Generation on Shutterstock<p><strong>What is the "continued-influence" effect?</strong></p><p>A challenge in using corrections effectively is that repeating the misinformation can have negative consequences. Research on this effect (referred to as "continued-influence") has shown that information presented as factual that is later deemed false can still contaminate memory and reasoning. The persistence of the continued-influence effect has led researchers to generally recommend avoiding repeating misinformation. </p><p>"Repetition increases familiarity and believability of misinformation," <a href="https://engineering.stanford.edu/magazine/article/how-fake-news-spreads-real-virus" target="_blank" rel="noopener noreferrer">the study explains</a>.</p><p><strong>What is the "familiarity-backfire" effect?</strong></p><p>Studies of this effect have shown that increasing misinformation familiarity through extra exposure to it leads to misattributions of fluency when the context of said information cannot be recalled. <a href="https://journals.sagepub.com/doi/10.1177/0956797620952797#" target="_blank" rel="noopener noreferrer">A 2017 study</a> examined this effect in myth correction. Subjects rated beliefs in facts and myths of unclear veracity. Then, the facts were affirmed and myths corrected and subjects again made belief ratings. The results suggested a role for familiarity but the myth beliefs remained below pre-manipulation levels. </p>