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Scientists shine a laser through a human head

spectrum.ieee.org

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Re: Scientists shine a laser through a human head

#41

Post by cma »

shadowgovt wrote: post #28
HelloUsername wrote: post #4

The title made me think of Anatoli Bugorski, a Soviet scientist who in 1978 survived a high-energy proton beam from a particle accelerator passing through his head. https://en.wikipedia.org/wiki/Anatoli_Bugorski

There's a lot of pieces of the physics of that story I don't quite understand. The main one is that (IIUC) one of the reasons the damage wasn't as bad as it could have been is that at the relativistic speeds the protons were travelling at, his head was extremely space-dilated, so they were basically blasting through tissue paper. But I would expect that tissue paper to have all the mass of a human head dilated into a…

Thinner makes it get through faster if it doesn't collide. If it is a charged particle dwell time is important as it usually doesn't collide unless its charge interacts with other charged particles enough to slow itself down giving it more time to interact with charged particles. This is how I understand ion beam deposition in silicon to work at least, it goes to a predictable depth and if the silicon is thinner than that it goes on through most of the time.

Thinner and denser then makes it interact more per unit time but any induced charge imbalances have closer neighboring material to rebalance charge shifts with, maybe you have a better chance of getting through the same number of particles over a shorter distance than at higher distance.

You definitely have a better chance faster than slower. its when it slows to a critical speed its non-collision charge based interactions build.

Re: Scientists shine a laser through a human head

#42

Post by pier25 »

ben_w wrote: post #13
hollerith wrote: post #11

>The group measured the times that millions of photons took to travel from a 1.2-watt laser emitting 800-nanometer wavelength light into one side of the head to a detector on the other side. Sunlight contains copious amounts of 800-nm light, so this is probably completely non-hazardous.

While it's almost certainly safe or it wouldn't have passed the ethics committee, what you say is an insufficiently detailed description of setup to determine if it's fine or not. 1.2 watts over your entire head is fine. 1.2 watts in a 800nm-diameter cylindrical path is "for some reason we decided to make the outer few millimetres of your skin explode, but we had to be in contact with your skin to manage that because…

Yeah but to be pedantic 800nm is the wavelength of the light of the laser :)

Re: Scientists shine a laser through a human head

#44

Post by ben_w »

pier25 wrote: post #42
ben_w wrote: post #13

Earlier quoted context omitted.

While it's almost certainly safe or it wouldn't have passed the ethics committee, what you say is an insufficiently detailed description of setup to determine if it's fine or not. 1.2 watts over your entire head is fine. 1.2 watts in a 800nm-diameter cylindrical path is "for some reason we decided to make the outer few millimetres of your skin explode, but we had to be in contact with your skin to manage that because…

Yeah but to be pedantic 800nm is the wavelength of the light of the laser :)

Which is why I chose that spot size :P

Technically it is possible to focus on things a bit smaller than a wavelength, but not by much and some of the options don't even work far from the lens itself.

https://en.wikipedia.org/wiki/Diffraction-limited_system#The...

Re: Scientists shine a laser through a human head

#45

Post by codedokode »

cogman10 wrote: post #29
astrobe_ wrote: post #24

Earlier quoted context omitted.

What can one actually do with a 1 Watt laser? That's a good question to ask to an AI: "A 1-watt laser can be used for various applications, such as cutting materials, engraving, and even lighting cigarettes. However, it poses significant risks, including the potential to cause instant and permanent eye injuries, so safety precautions are essential". So it looks like it packs some... Power. But I guess the frequency o…

Energy is what your looking for. Static electricity discharges at around 400 to 600W. Yet it's for an extremely brief amount of time. Sub millisecond usually) so the actual energy transferred is minimal. It takes around 1Wh to heat a liter of water 1 degree just to put things in perspective.

The laser concentrates the power in a small spot that's why it is more dangerous. Consider what 1W would do to 1 mm³ of water.

Re: Scientists shine a laser through a human head

#46

Post by astrobe_ »

addaon wrote: post #31
astrobe_ wrote: post #24

Earlier quoted context omitted.

What can one actually do with a 1 Watt laser? That's a good question to ask to an AI: "A 1-watt laser can be used for various applications, such as cutting materials, engraving, and even lighting cigarettes. However, it poses significant risks, including the potential to cause instant and permanent eye injuries, so safety precautions are essential". So it looks like it packs some... Power. But I guess the frequency o…

> That's a good question to ask to an AI What makes you say that? By what metric?

I think at least it is good at answering questions that have been asked before, in some way or another. But the real question is, why didn't I also ask my follow up question to it, instead of trying to talk with humans? I think I prefer to learn from real people with hands-on experience, and maybe hear amazing or amusing stories in the process.

Re: Scientists shine a laser through a human head

#47

Post by genocidicbunny »

FirmwareBurner wrote: post #25
brenainn wrote: post #10

Earlier quoted context omitted.

Me too! Amazing that he's still alive.

Yes but ... "In 1996, Bugorski applied unsuccessfully for disability status to receive free epilepsy medication. Bugorski showed interest in making himself available for study to Western researchers but could not afford to leave Protvino." This is just sad all around through and through.

Not to excuse it, but Protvino in the 90's was...kind of a shitshow. The early 90's were a little like post-war UK - think food stamps, standing in line all morning just to buy your measly weekly meat allotment, most city services on the brink of failure. Many of the chronically sick or disabled, or injured veterans, ended up basically being kicked to the curb when they no longer had the social safety net that (however low or high quality) they had in the USSR.

It took heroic efforts to leave to the west in those times. The best most people could swing was finding work in Moscow or Serpuhov and commuting there on the daily. And this is all considering that it was a 'science town'; Many of those who lived there in some way worked at or adjacent to the accelerator institute and were fairly well educated individuals.

Re: Scientists shine a laser through a human head

#48

Post by grues-dinner »

Onavo wrote: post #17

Did they figure out the dark hair issue? It's been a major problem for fNIR systems.

It's interesting to me that hair or skin colour make such a difference when it's only a mm or two out of a far thicker solid lump of brain, bone and so on.

Re: Scientists shine a laser through a human head

#49

Post by echelon »

throwaway173738 wrote: post #35
short_sells_poo wrote: post #19

Earlier quoted context omitted.

This would likely require completely new forms of physics and interacting with matter I'm afraid. It simultaneously requires extremely high resolution and high penetration (we need to see deep into the brain). You'll need to be able to measure the state of neurons and connections - probably down to the quantum level - and do this real time, and then record the data that you collected. I suppose you could flood the br…

At least there’s a theoretical path forward to super-luminal travel beyond hand-waving. Just find some exotic negative energy density matter.

We have more people thinking about super-luminal travel than people thinking about BCI, brain scanning, brain uploads, and digital immortality.

We've kind of got this whole thing backwards.

Re: Scientists shine a laser through a human head

#50

Post by Onavo »

stronglikedan wrote: post #34
Onavo wrote: post #17

Did they figure out the dark hair issue? It's been a major problem for fNIR systems.

Could they just shave an area, like they do for procedures? (and whenever I have to get an EKG because my chest hair is apparently adhesive resistant)

You can but it makes it useless for general purpose BCI. Your average consumer complains when they have to put electro gel on for normal EEGs.
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