Sep 18, 2019 02:15 AM
(This post was last modified: Sep 18, 2019 04:06 AM by C C.)
Origin-of-Life Study Points to Chemical Chimeras, Not RNA (biochemistry)
https://www.quantamagazine.org/origin-of...-20190916/
EXCERPT: Four billion years ago, the prebiotic Earth was a messy place, a chaotic mélange of diverse starting materials. Even so, certain key molecules still somehow managed to emerge from that chemical mayhem — RNA, DNA and proteins among them. But in the quest to understand how that happened, according to Ramanarayanan Krishnamurthy, a chemist at the Scripps Research Institute in California, researchers have been so myopic in their focus on reactions that generate molecules relevant to the planet’s current inhabitants that they’ve overlooked other possibilities.
“They are trying to impose biology today on prebiotic chemistry,” he said. “But trying to make the final product right from the raw material — it misleads us.” “We forget the mixture,” he added — and with it, the more circuitous chemical routes that could have potentially led to the same biological outcome, the intermediate stages on the path to life that have since faded without a trace.
It makes sense that experimentalists preferred to keep things clean and direct [...] But research is beginning to show that starting with the right kind of mess is not only more realistic, but more effective at generating the materials vital to life, while also doing away with problems that have plagued purer systems. “There are times when we have mixtures, rather than just the isolated reactants that people typically use, and we get better results,” said Nicholas Hud, a chemist at the Georgia Institute of Technology. When mixtures are taken into consideration, the emergence of life on Earth in some ways “is not as hard as we might think it is.”
n the most compelling evidence to date, Krishnamurthy and a postdoctoral researcher in his lab, Subhendu Bhowmik, looked at how a system of chimeric RNA-DNA molecules — molecules built from the chemical units of both RNA and DNA — produced pure RNA and pure DNA more easily than systems that started out pure. The work, published today in Nature Chemistry, highlights just how essential a diverse, complex blend of ingredients may have been to life’s earliest evolution. (MORE - details)
Why do some scientists believe that our universe is a hologram? (theoretical physics)
https://backreaction.blogspot.com/2019/0...t-our.html
INTRO: Today, I want to tell you why some scientists believe that our universe is really a 3-dimensional projection of a 2-dimensional space. They call it the “holographic principle” and the key idea is this.
Usually, the number of different things you can imagine happening inside a part of space increases with the volume. Think of a bag of particles. The larger the bag, the more particles, and the more details you need to describe what the particles do. These details that you need to describe what happens are what physicists call the “degrees of freedom,” and the number of these degrees of freedom is proportional to the number of particles, which is proportional to the volume.
At least that’s how it normally works. The holographic principle, in contrast, says that you can describe what happens inside the bag by encoding it on the surface of that bag, at the same resolution. This may not sound all that remarkable, but it is. Here is why... (MORE)
https://www.youtube-nocookie.com/embed/dmDKlcaAWO0
https://www.quantamagazine.org/origin-of...-20190916/
EXCERPT: Four billion years ago, the prebiotic Earth was a messy place, a chaotic mélange of diverse starting materials. Even so, certain key molecules still somehow managed to emerge from that chemical mayhem — RNA, DNA and proteins among them. But in the quest to understand how that happened, according to Ramanarayanan Krishnamurthy, a chemist at the Scripps Research Institute in California, researchers have been so myopic in their focus on reactions that generate molecules relevant to the planet’s current inhabitants that they’ve overlooked other possibilities.
“They are trying to impose biology today on prebiotic chemistry,” he said. “But trying to make the final product right from the raw material — it misleads us.” “We forget the mixture,” he added — and with it, the more circuitous chemical routes that could have potentially led to the same biological outcome, the intermediate stages on the path to life that have since faded without a trace.
It makes sense that experimentalists preferred to keep things clean and direct [...] But research is beginning to show that starting with the right kind of mess is not only more realistic, but more effective at generating the materials vital to life, while also doing away with problems that have plagued purer systems. “There are times when we have mixtures, rather than just the isolated reactants that people typically use, and we get better results,” said Nicholas Hud, a chemist at the Georgia Institute of Technology. When mixtures are taken into consideration, the emergence of life on Earth in some ways “is not as hard as we might think it is.”
n the most compelling evidence to date, Krishnamurthy and a postdoctoral researcher in his lab, Subhendu Bhowmik, looked at how a system of chimeric RNA-DNA molecules — molecules built from the chemical units of both RNA and DNA — produced pure RNA and pure DNA more easily than systems that started out pure. The work, published today in Nature Chemistry, highlights just how essential a diverse, complex blend of ingredients may have been to life’s earliest evolution. (MORE - details)
Why do some scientists believe that our universe is a hologram? (theoretical physics)
https://backreaction.blogspot.com/2019/0...t-our.html
INTRO: Today, I want to tell you why some scientists believe that our universe is really a 3-dimensional projection of a 2-dimensional space. They call it the “holographic principle” and the key idea is this.
Usually, the number of different things you can imagine happening inside a part of space increases with the volume. Think of a bag of particles. The larger the bag, the more particles, and the more details you need to describe what the particles do. These details that you need to describe what happens are what physicists call the “degrees of freedom,” and the number of these degrees of freedom is proportional to the number of particles, which is proportional to the volume.
At least that’s how it normally works. The holographic principle, in contrast, says that you can describe what happens inside the bag by encoding it on the surface of that bag, at the same resolution. This may not sound all that remarkable, but it is. Here is why... (MORE)