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QOTD: What's the coolest fact you know?

IOnceWasLegend

IOnceWasLegend

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Learning new things is always fun. So: what's the coolest fact you know?

I studied neuroscience, so my favorite: you have more cells in your brain than there are stars in our galaxy. There's ~100 billion stars in our galaxy, and ~100 billion neurons (electrically active) cells, but neurons are only a fraction of the cells in your brain.

What's even more insane is that your brain has between 1,000 and 10,000 connections (synapses) for each cell.

The brain is fascinating and complex!
 
Well one's definition of "cool" may definitely vary greatly from others but....

In stars like our Sun fusion occurs via a process called the Proton-Proton chain, the basics is ionized hydrogen fuse together over a series of events and ultimately 4 hydrogen turn into one helium, this take a lot of heat AND pressure this is because the hydrogen ions are just protons and two protons don't want to be near each other at all so the heat makes everything wiggle around really fast and the pressure holds it close so that you can get collisions that eventually "stick" hence fusion. In stars that are heavier than our Sun when they fuse hydrogen they use a different method called the CNO cycle, now the net result is the same 4 hydrogen turn into 1 helium but the way it does it involves Carbon, Nitrogen and Oxygen, without boring you of the details this occurs it heavier stars because the cores are hotter and there's even more pressure, and instead of 2 protons that don't want to be near each other, 1 proton (hydrogen) doesn't want be near the 6 protons of a carbon (6 times the repulsive force at similar distances).

Now when stars stop fusing hydrogen into helium in their core if they have enough mass they will enter their giant phase of their life, and one particular stage of this giant phase is helium fusion in the core (from all that hydrogen fusion earlier), now helium has 2 protons, so squeezing 2 and 2 together seems like it would require less effort than squeezing 1 proton and 6 protons together and you'd be 100% right, however the temperatures required for helium fusion are tremendously greater than what is needed for the CNO cycle.

The reason for this is my interesting fact, when 4 hydrogen atoms fuse into 1 helium atom the reason why that makes energy is because the 1 helium atom has less mass than the 4 hydrogen atoms that went into it, this tiny amount of mass gets turned into energy (E=mc²), however when 2 helium atoms fuse what the turn into is beryllium atom there actually is MORE mass after the fusion, meaning that it takes energy to do (translation: star would get cooler) as a result the beryllium will decay back into helium with a half-life of about 10^-16 seconds (aka super quick), however the magic is in the high temperature, because temperatures exceed 100 million Kelvin in these reactions (compared to the puny 15 million Kelvin that our Sun does) if another helium fuses with the beryllium before the process can decay it will form carbon which has less mass than 3 helium ions, and a net energy gain is made by sequence.

And much like one of my classese that I teach this in, I can imagine quiet bored looks staring at the screen with the occasional blink.
 
Medical imaging is pretty sci-fi already.

PET- The radionuclide injected releases positrons inside your body, which are the antimatter of electrons. These antimatter particles fly off in a random direction, then very soon hit one of your electrons, causing both to annihilate. This sends off the equivalent energy of both particles in opposite directions as high-energy photons, which is what we see outside the body to form a picture.

MRI- Very strong magnetic fields cause the protons (H+) in all the water molecules of your body to line up in one direction rather than aligning randomly like they normally do. As they move back to their preferred alignment, and in response to other manipulations, they let off radio waves, which is what we see outside the body to form a picture. Also, was originally called Nuclear Magnetic Resonance Imaging, but when people saw the word Nuclear they started protesting in SF, so the pioneers of the field just dropped the Nuclear part of the name and the demonstrators went away.
 
JVU said:
Medical imaging is pretty sci-fi already.

PET- The radionuclide injected releases positrons inside your body, which are the antimatter of electrons. These antimatter particles fly off in a random direction, then very soon hit one of your electrons, causing both to annihilate. This sends off the equivalent energy of both particles in opposite directions as high-energy photons, which is what we see outside the body to form a picture.

MRI- Very strong magnetic fields cause the protons (H+) in all the water molecules of your body to line up in one direction rather than aligning randomly like they normally do. As they move back to their preferred alignment, and in response to other manipulations, they let off radio waves, which is what we see outside the body to form a picture. Also, was originally called Nuclear Magnetic Resonance Imaging, but when people saw the word Nuclear they started protesting in SF, so the pioneers of the field just dropped the Nuclear part of the name and the demonstrators went away.
Click to expand...
Yes, I was in grad school doing NMR work and actually remember the NMR MRI squabble.
 
Wlachnit said:
Yes, I was in grad school doing NMR work and actually remember the NMR MRI squabble.
Click to expand...
Yup, one of my first classes teaching was basically "physics for medical personnel" which primarily were nurses since there was a program at that school for nursing. Telling them always got a chuckle, and inside I died because I'm thinking "no really... people who didn't know anything about the subject were almost responsible for a very important medical tool to never happen that had nothing to do with what they were protesting"
 
I’ve always been fascinated by renewable energy and how far its progressed over the years. California has made great strides towards a low-carbon grid, mostly though solar and wind generation, however, the rapid rise in solar and wind resources coming into the power grid has created a new operating paradigm. The energy system has too much renewable energy but does not have the adequate capabilities to utilize the energy effectively. There is more renewable energy supplied than what is being demanded (but only for a few minutes of the day around noon). What’s interesting is, at that point in the day, traditional energy producers (i.e. PG&E) are running their systems at minimal output. Just enough to keep the system on. However, the traditional energy producers need to be ready to ramp up when energy demand supersedes renewable supply. Shutting down and restarting their system would take hours and because their systems can only operate at such a minimal level, we are essentially wasting the surplus of renewable energy. It’s a new/good problem to have, but I’m interested to see how these big utility companies respond. Elon wants to make a big battery! Hope that sparked an interest!
 
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