Avoiding an Empty Universe with Solitary Neutrinos (史蒂夫·比勒 Physics)
(正如一位伟大的物理学家曾经说过的), 光了, 还有等量的物质和反物质. This is because the universe started as an empty vacuum (which turns out to be much more complicated than “nothing,但那是另一个话题了). So, 为了保持平衡, 如果你产生一点物质, you also need to produce something that could annihilate with it to get back to a vacuum: anti-matter. The problem is that this annihilation should have largely happened at some point and the universe should be pretty much empty… a truly lonely place, where the light produced by that annihilation wanders a vast universe on its own. As it is, we’re here, and we don’t see huge chunks of anti-matter lying about (both a good thing!). 因此, 在宇宙早期的某个时刻, an imbalance between matter and anti-matter must have developed so as to allow something to survive to today. 随便问一个物理学家这是怎么发生的，为什么会发生, and their answer will be quick and easy to understand: we don’t know. 这是科学界最大的谜团之一. 然而, we do know something of the underlying 体育sics conditions that are necessary for it to happen, 这要感谢俄罗斯物理学家安德烈·萨哈罗夫, who was himself isolated from society by the Soviet Union for his peace activism (for which he won the Nobel Peace Prize in 1975). Sakharov laid out the requirements to avoid an empty universe over 50 years ago.
The Sakharov conditions are as follows: 1) “Baryon number violation,” which allows for protons and neutrons (which make up atoms) and their corresponding anti-particles to be able to appear and disappear. 但这本身不会造成不平衡, so you also need 2) something called “C and CP violation,” which allows the rates of those appearances and disappearances to be different for anti-particles. 最后, the universe must be 3) “out of thermodynamic equilibrium,” which means it cannot be in a situation where the nature of interactions keeps things the same. 宇宙必须改变. That last condition is the only one we’ve observed: it’s the Big Bang and the subsequent expansion of the universe. Baryon number violation has been looked for and not found. C and CP violation have been seen in the interactions of quarks, 是什么组成了质子和中子, 但这还不足以解释这一切. 这是在哪里发生的?
让非凡体育首页来看看最孤独的粒子, the neutrino: a particle that barely interacts with anything. 中微子是在核衰变中产生的, 超新星, the Big Bang and are one of the most abundant things in the universe, 但他们几乎看不到宇宙. This special kind of isolation from common interactions makes them particularly challenging to even detect. Yet this particle has already thrown up a wealth of surprises. Neutrinos have extremely small masses, though the Standard Model says they shouldn’t have any. There are 3 types of neutrinos that seem to exist in “mixed stated,” which allow them to transform into each other as they travel, though we don’t really understand why they mix as they do. 最后一个性质的观察, 这是基于观测太阳的中微子, 赢得了我的最后一次实验, the Sudbury Neutrino Observatory (SNO) the Nobel Prize in 2015. Now there is a suspicion that neutrinos might also be able to fulfil the last of the Sakharov conditions. There are already strong hints that they violate C and CP symmetries and they are the only fundamental particle that could potentially have the ability to transform into their own anti-particles, 以及转化成其他类型的中微子. 如果是这样的话, then there is a secret back door available in the early universe, 当天气非常炎热的时候, that would allow an imbalance in neutrinos to propagate to the protons and neutrons, 从而满足萨哈罗夫的所有条件! 搜索ing for evidence of neutrinos flipping to anti-neutrinos is the main goal of my current project, SNO +, 对原SNO实验的修正. It will involve looking for an extremely rare radioactive decay that would be made possible by this transformation. 这是一项极具挑战性的努力, 还有哪些其他团体也在尝试, 这可能需要很多年才能找到, 这取决于衰变的速度. But this esoteric study could reveal one of the biggest answers of all: how the universe managed to survive cataclysmic annihilation and emptiness, to let us be here together to ponder neutrinos in the first place!
SNO +主页: http://snoplus.phy.queensu.ca/
- 3rd and 4th Century Social Distancing in the Desert (Jenn Strawbridge, Theology)
- Avoiding an Empty Universe with Solitary Neutrinos (史蒂夫·比勒 Physics)
- Daniel Defoe's Journal of the Plague Year (Ros Ballaster, English)
- Doing Community in Isolation: Mosques, Mecca and One Direction
- Isolation and Revelation (Alison Salvesen, Oriental Studies)
- Physically, but not socially, isolated: Insights from a small Micronesian island
- Power and politics amidst COVID-19 seclusions—perspectives from geogra体育 (Amber Murrey, Geogra体育)
- Samuel Taylor Coleridge’s ‘Fears in Solitude’ (Ruth Scobie, English)
- Social Distancing in Ancrene Wisse (Lucinda Rumsey, English)
- Social distancing and quantum computing – are we all qubits now? (Jason Smith，材料科学)
- Thomas Nashe: ‘Plague’s Prisoner’ (Chris Salamone, English)
- Even buildings need isolation (Sinan Acikgoz, Engineering)