from the world's big
The outer edges of a black hole might be "fuzzy" instead of neat and smooth.
- A recent study analyzed observations of gravitational waves, first observed in 2015.
- The data suggests, according to the researchers, that black holes aren't bounded by smooth event horizons, but rather by a sort of quantum fuzz, which would fit with the idea of Hawking radiation.
- If confirmed, the findings could help scientists better understand how general relativity fits with quantum mechanics.
ESO, ESA/Hubble, M. Kornmesser<p>In the 1970s, Stephen Hawking famously proposed that black holes aren't truly "black." In simplified terms, the theoretical physicist reasoned that, due to quantum mechanics, black holes actually emit tiny amounts of black-body radiation, and therefore have a non-zero temperature. So, contrary to Einstein's view that black holes are neatly defined and are not surrounded by loose materials, Hawking radiation suggests that black holes are actually surrounded by quantum "fuzz" that consists of particles that escape the gravitational pull.</p><p>"If the quantum fuzz responsible for Hawking radiation does exist around black holes, gravitational waves could bounce off of it, which would create smaller gravitational wave signals following the main gravitational collision event, similar to repeating echoes," Afshordi said.</p>
Credit: NASA's Goddard Space Flight Center/Jeremy Schnittman<p>A new study from Afshordi and co-author Jahed Abedi could provide evidence of these signals, called gravitational wave "echoes." Their analysis examined data collected by the <a href="http://www.virgo-gw.eu/" target="_blank">LIGO and Virgo gravitational wave detectors</a>, which in 2015 detected the first direct observation of gravitational waves from the collision of two distant neutron stars. The results, at least according to the researchers' interpretation, showed relatively small "echo" waves following the initial collision event.</p><p>"The time delay we expect (and observe) for our echoes ... can only be explained if some quantum structure sits just outside their event horizons," Afshordi told <em><a href="https://www.livescience.com/black-hole-echoes-unsettle-einstein-relativity.html" target="_blank">Live Science</a>.</em></p>
Afshordi et al.<p>Scientists have long studied black holes in an effort to better understand fundamental physical laws of the universe, especially since the introduction of Hawking radiation. The idea highlighted the extent to which general relativity and quantum mechanics conflict with each other. </p><p>Everywhere — even in a vacuum, like an event horizon — pairs of so-called <a href="https://www.scientificamerican.com/article/something-from-nothing-vacuum-can-yield-flashes-of-light/" target="_blank">"virtual particles"</a> briefly pop in and out of existence. One particle in the pair has positive mass, the other negative. Hawking imagined a scenario in which a pair of particles emerged near the event horizon, and the positive particle had just enough energy to escape the black hole, while the negative one fell in.</p><p>Over time, this process would lead black holes to evaporate and vanish, given that the particle absorbed had a negative mass. It would also lead to some interesting <a href="https://en.wikipedia.org/wiki/Black_hole_information_paradox#Recent_developments" target="_blank">paradoxes</a>.</p><p>For example, quantum mechanics predicts that particles would be able to escape a black hole. This idea suggests that black holes eventually die, which would theoretically mean that the physical information within a black hole also dies. This violates a key idea in quantum mechanics which is that physical information can't be destroyed.</p><p>The exact nature of black holes remains a mystery. If confirmed, the recent discovery could help scientists better fuse these two models of the universe. Still, some researchers are skeptical of the recent findings.</p><p>"It is not the first claim of this nature coming from this group," Maximiliano Isi, an astrophysicist at MIT, <a href="https://www.livescience.com/black-hole-echoes-unsettle-einstein-relativity.html" target="_blank">told</a> Live Science. "Unfortunately, other groups have been unable to reproduce their results, and not for lack of trying."</p><p>Isi noted that other papers examined the same data, but failed to find echoes. Afshordi told <em>Galaxy Daily</em>:</p><p>"Our results are still tentative because there is a very small chance that what we see is due to random noise in the detectors, but this chance becomes less likely as we find more examples. Now that scientists know what we're looking for, we can look for more examples, and have a much more robust confirmation of these signals. Such a confirmation would be the first direct probe of the quantum structure of space-time."</p>
From talking about Schrödinger's cat to nuking the South Pole, this decades-old interview shows why Kaku was born to be a science educator.
- Michio Kaku is a theoretical physicist and renowned science communicator.
- In 1991, he sat down for an hour-long interview in which he discussed climate change, nuclear weapons, human evolution, and more.
- Kaku is a regular contributor to Big Think.
The end of the ice age paved the way for agriculture (and slavery)<p>The most recent ice age made it nearly impossible for humans to develop sophisticated societies.<br></p><p>"We were almost indistinguishable from animals: the way we lived, the way we foraged for food, the way we hunted," Kaku said. "We had no civilization to speak of."</p><p>But then everything changed. </p><p>"An absolutely stupendous event took place 12,000 years ago. The Ice Age ended. And with the melting of the ice, it meant that humans no longer had to follow the deer, follow the bears. It meant that humans could plant seeds, and, coming back a year later, these seeds would sprout. And with that, agriculture developed."</p><p>Kaku said the development of agriculture was a key turning point in humanity's evolution. </p><p>"With agriculture, it meant that you didn't have to follow the deer," he said. "It meant that you could sit down and build a village [...] With the coming of villages came cities."</p><p>But the development of large cities also enabled some of the darker sides of humanity to manifest. </p><p>"With the coming of cities came the division of labor, and with the division of labor came, unfortunately, slavery, where humans subjugated other humans. You can't have slavery when you are in bands of only 10 people foraging for deer. You can have slavery if your population develops to 10,000 [or] 20,000."</p><p><em>Excerpt starts around 16 minutes into the interview.</em><br></p>
Kaku predicts climate change by 2030<p>Global warming allowed humans to develop civilization, but its "catastrophic effects" might also destroy it, Kaku said in 1991.<br></p> <p>"The question is: Now that we are heating up the atmosphere with carbon dioxide, the latest projections that I've seen is that, early in the next century, we will heat the atmosphere to perhaps 4 to 9 degrees [measured against 1980] because of carbon dioxide being pumped into the atmosphere."</p> <p>The Intergovernmental Panel on Climate Change <a href="https://www.ipcc.ch/sr15/resources/headline-statements/" target="_blank">predicts</a> that global warming "is likely to reach 1.5°C between 2030 and 2052 if it continues to increase at the current rate."</p><p><em>19:15</em><br></p>
Kaku talks nuking the South Pole<p>What's a relatively straightforward way to transform global ecosystems and potentially end humanity as we know it?<br></p> <p>"All you have to do is put our nuclear arsenal on the South Pole and detonate the South Pole, and melt it. We have the capability of altering the entire eco-structure of the planet with our hydrogen bombs."</p> <p>Of course, Kaku wasn't suggesting people do such a thing. Rather, he was highlighting the precarity of the nuclear age: At any moment, one person with a bomb could, theoretically, transform the entire world.</p><p><em>21:10</em><br></p>
Kaku talks about the possibility of extinct alien civilizations<p>After discussing the perils of nuclear weapons, Kaku noted that all civilizations throughout the universe would eventually come to a crossroads when they discover uranium.<br></p> <p>"If the <a href="https://bigthink.com/scotty-hendricks/where-are-all-the-aliens-a-famous-physicist-gives-an-answer-you-might-not-like" target="_self">work of Frank Drake</a> is correct, it means, potentially, there could be thousands of dead planets out there that did not negotiate pollution — global pollution, like the greenhouse effect, and the global pollution, like the depletion of the ozone layer — and did not negotiate the question of nuclear weapons."</p> <p>Kaku also said that it's possible that humans are an "evolutionary dead-end," if we fail to properly manage technological advances.</p> <p><em>25:30</em></p>
The main obstacle in curbing climate change<p>When asked whether humans have the capability to mitigate the effects of climate change, Kaku said yes, but it all comes down to the "almighty dollar."<br></p> <p>"We have the means, we don't have the will," he said. "Unfortunately, it's like a driver driving in a car, getting all of a sudden very sleepy, and it takes a near-miss to wake up that person. That's civilization. Civilization is falling asleep when it comes to [...] the catastrophic depletion of the ozone layer, and the greenhouse effect. And it may take a near-miss. The problem is that, even after we wake up, it may be too late."</p> <p>Kaku later noted that former President George H. W. Bush was the president of an oil company. </p> <p>"The problem is that the engine of the industrial revolution has been profits," Kaku said. "There's no profit to be made to restrict the ozone layer. There's no profit to be made to restrict the greenhouse effect...Oilmen like the greenhouse effect, because the greenhouse effect is called by oil."</p> <p><em>49:30</em></p>
If philosophers don't try to mesh their long-held views with new scientific insights, then we have a problem.
- According to panpsychists, all of reality is infused with experience. In other words, the fundamental ingredient of reality, they believe, has the felt quality of experience in it.
- In this view, the reason that we humans are conscious is that we're configured based on these fundamental experiential ingredients.
- If philosophers don't try to mesh their long-held views with what we're discovering from good science, then we have a problem. For instance, panpsychism may be due for an update: panprotopsychism, a view that says as these fundamental ingredients combine, they give rise to conscious experience and that those fundamental ingredients are "quasimental."
New experiments look to the interplay between neutrons and magnetic fields to observe our universal reflection.
- Science fiction has long speculated about parallel universes and what they may be like.
- Researchers have devised new experiments to look for how a mirror universe may be influencing our own.
- If such evidence is found, it could bring to light many of the universe's mysteries, such as the nature of dark matter.
Searching for our own reflection<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8xOTU4ODUyMy9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY0OTIxMTI0OX0.0wDV6qQ_AaHZ80H2F-pwXIqP1v9SLYxINGyeAiNXd7g/img.jpg?width=980" id="db810" class="rm-shortcode" data-rm-shortcode-id="ead1d29f3e507632e31f1017a77de516" data-rm-shortcode-name="rebelmouse-image" />
At the Oak Ridge National Laboratory's traveling science fair, participants can experience life as a ion and then a neutron in a neutron beam. Photo credit: Genevieve Martin / ORNL / Flickr<p>The first experiment profiled by <em>New Scientist </em>comes courtesy of physicist Leah Broussard and her team at the Oak Ridge National Laboratory in Tennessee. They have devised a simple method for detecting a mirror universe.</p><p>An apparatus will fire a beam of neutrons at a wall with varying magnetic fields on both sides. These neutrons can't penetrate the wall, yet the researchers have placed a device behind it that will scan the area for these very subatomic particles.</p><p>Why? If any neutrons manage to appear behind the wall, it will be strong evidence that they oscillated into mirror neutrons, skipped right on pass the wall because it existed in a different part of the universe, and then oscillated back in time to hit the detection device.</p><p>"Only the [neutrons] that can oscillate and then come back into our universe can be detected," Broussard told <em>New Scientist</em>. "When passing through a magnetic field, the oscillation probability increases."</p><p>Broussard and her team are looking at neutrons because of a quirk in their decay. </p><p>Inside a nucleus, neutrons are perfectly stable, but outside, <a href="https://hepweb.ucsd.edu/ph110b/110b_notes/node63.html" target="_blank">they decay</a> into a proton, an electron, and an antineutrino of the electron type. Here's the quirk: all free neutrons should decay at the same rate, but that rate changes depending on how scientists measure it.</p><p>The first way to measure <a href="https://phys.org/news/2018-05-levitation-yields-neutron-lifetime.html" target="_blank">the lifetime of free neutrons</a> is to isolate them in a "bottle trap" and then count how many remain after a certain amount of time. The second way is to count the protons emerging from a neutron beam generated by a nuclear reactor. Yet, scientists get different rates of decay for each — 14 minutes 39 seconds for the former, 14 minutes 48 seconds for the latter. </p><p>A possible explanation for this discrepancy is a mirror universe. Neutrons may have dual citizenship in both universes. When they summer in our neighboring universe, any protons they emit are not detected and therefore not counted in our measurements. This could explain why we see less decay activity in the neutron beam.</p>
Signals in magnetic fields<p>The second experiment profiled by <em>New Scientist</em> was developed by Klaus Kirch and his team at the Paul Scherrer Institute in Switzerland. This team applied magnetic fields of varying strengths to neutrons in a bottle trap.</p><p>The goal is to find the telltale signals of mirror magnetic fields. These would suggest neutrons oscillating between universes, potentially supporting any evidence found by Broussard and her team.</p><p>"The experimentalist's view is, if it doesn't look completely crazy, can it be tested?" Kirch told <em>New Scientist</em>. "I don't really believe the signals are there, and we have designed an experiment that can disprove them, and we'll see what comes out of it."</p><p>Kirch and his team have completed their experiment and are currently analyzing the data.</p>
A mirror darkly<div class="rm-shortcode" data-media_id="dOCyeg9W" data-player_id="FvQKszTI" data-rm-shortcode-id="12b67c60548023984cf6b07c1129f125"> <div id="botr_dOCyeg9W_FvQKszTI_div" class="jwplayer-media" data-jwplayer-video-src="https://content.jwplatform.com/players/dOCyeg9W-FvQKszTI.js"> <img src="https://cdn.jwplayer.com/thumbs/dOCyeg9W-1920.jpg" class="jwplayer-media-preview" /> </div> <script src="https://content.jwplatform.com/players/dOCyeg9W-FvQKszTI.js"></script> </div> <p>As Yuri Kamyshkov, a mirror matter researcher at the University of Tennessee and a collaborator with Broussard, noted: "The probability of finding anything is low, but it's a simple and inexpensive experiment." Despite the odds, he adds, a positive result would usher in a physics revolution.</p><p>A mirror universe could explain many of physics' unsolved mysterious, among them the question of dark matter. As <a href="https://bigthink.com/dr-kakus-universe/what-is-dark-matter" target="_self">Michio Kaku told <em>Big Think</em></a> in an interview:</p><p style="margin-left: 20px;">"Dark matter is massive, it has gravity, but it's invisible. It has no interactions with light or the electromagnetic force. So, there is a theory that says that perhaps dark matter is nothing but matter, ordinary matter, in another dimension hovering right above us."</p><p>Of course, Kaku points out, this is one of many different theories about dark matter. String theorists think dark matter may be a higher octave of string vibration.</p><p>One reason the mirror universe idea is so appealing is the math. Some models suggest a mirror universe would have to have been much cooler than our own during its early evolution. This difference would have made it easier for particles to cross over, resulting in five mirror particles for every regular one. That's roughly the ratio of dark to normal matter.</p><p>Scientific models, in the end, must be backed by empirical evidence. We'll have to wait for the results of these and other experiments before determining the probability that a mirror universe exists — let alone if its beard game can match our own.</p>
Cosmologists propose a groundbreaking model of the universe using string theory.
- A new paper uses string theory to propose a new model of the universe.
- The researchers think our universe may be riding a bubble expanded by dark energy.
- All matter in the universe may exist in strings that reach into another dimension.