7 ms·

Bit flips from cosmic rays. Earth’s magnetic field helps to shield us, but is disrupted now. I work with a CCD camera in a sub basement lab. On a normal day we

by rrock 3y ago

Bit flips from cosmic rays. Earth’s magnetic field helps to shield us, but is disrupted now. I work with a CCD camera in a sub basement lab. On a normal day we see a stray cosmic ray every couple of minutes (as a hot pixel). On a day like today, might be every couple of seconds.

tudorw 3y ago
annoying, but kind of awesome :)
cshimmin 3y ago
True, but the hot pixels you see in the CCD isn't from bit flips. Rather the CCD is properly doing its job of collecting electrons. It's just that spurious electrons are being produced by the cosmic rays' ionization trail (as opposed to photoelectron in normal operation).
- anamexis 3y ago
  What's the difference? Aren't bit flips also just spurious electrons being produced by the cosmic rays' ionization trail?
  - akiselev 3y ago
    It’s an excitation of the sensor. It may be interpreted somewhat like a bit flip when converted to an image, but it’s normal for image sensors to experience a lot of noise, going back to the days of film. It may just be eliminated by the denoising algorithm like most spurious electrons/photons.
  - godelski 3y ago
    Bitflip is when a high energy particle changes the state of a memory address or signal in a wire. Hot pixels are when the CCD (camera sensor) achieves its max level and becomes bright. Pixel overloaded (should also result in spillover). Difference is really just what part of the system receives the energy. For example, you can overload a pixel with a laser, but you also should get spillover. Bit flips tend to be more localized, affecting only one part. In reality, the difference doesn't matter too much, as long as we're keeping our discussion to cosmic events. But also note that images experience a lot of (non-gaussian) noise and plenty of this is from cosmic excitation as well as from other natural and man made sources. Just the levels are a lot lower and unlikely to result in a bitflip (which is a pretty high energy event).
    - cshimmin 3y ago
      Pretty much this. But the point is that a bitflip would be like, your CCD was supposed to read out value 0b00000 = 0 but due to cosmic ray interference, it read out 0b10000 = 16 instead. Instead, what's happening in GGP's experiment is that actual electrons, created in the bulk of the active silicon region by a passing cosmic ray, are getting detected by the CCD, and it will (correctly) read out some value between 00000 and 11111, depending on how many electrons it saw. In principle you can actually make a histogram of these readout values and observe the Bethe-Bloch distribution of energy loss for ionizing particles through the (very thin) bulk of silicon! On the other hand, random bit flips (which are much rarer!) would just give you a random distribution of the numbers {00000, 00001, 00010, 00100, 01000, 10000}.
exitb 3y ago
That’s cool, is that some sort of specialized equipment, or could that observation be replicated by an amateur with a RAW-capable camera?
- csdvrx 3y ago
  Put a lid on. Continuously take pictures. Look for deltas in the pixel values
tivert 3y ago
>> I've always been hearing that solar flares and the resulting geomagnetic storms pose danger to hard drives and electronics. Is there any truth to it? > Bit flips from cosmic rays. I don't think that's it. IIRC, if a geomagnetic storm/coronal mass ejection is big enough, it can cause certain effects that are similar to an EMP. What the OP is talking about sounds like a distorted version of that danger: a nuclear EMP could directly fry microelectronics, a solar storm is a kind of EMP (solar EMP), but is missing most of the effects that could directly damage microelectronics, and many people conflate the two. https://en.wikipedia.org/wiki/Carrington_Event https://en.wikipedia.org/wiki/Carrington_Event https://en.wikipedia.org/wiki/Electromagnetic_pulse#Types https://en.wikipedia.org/wiki/Electromagnetic_pulse#Types
- cronix 3y ago
  Yes, but during the Carrington Event, electrical wires became overloaded and blowing out equipment attached to "the grid." I've had a computer blow out (sparks, smoke and everything) due to a power surge when the main power went out and then back on, rapidly. So while the "direct" causes might be different between EMP and CME, the end results are basically the same. I could only imagine what our current (very power sensitive) electronics would do in that scenario. From the wikipedia Carrington Event you posted: > Because of the geomagnetically induced current from the electromagnetic field, telegraph systems all over Europe and North America failed, in some cases giving their operators electric shocks.[22] Telegraph pylons threw sparks.
  - tivert 3y ago
    > I've had a computer blow out (sparks, smoke and everything) due to a power surge when the main power went out and then back on, rapidly. > So while the "direct" causes might be different between EMP and CME, the end results are basically the same. Not necessarily. My understanding is a CME solar EMP would take out grid-connected devices (via power surges over the grid), but leave most unconnected devices unharmed (e.g. laptops running on battery), but a nuclear EMP would take out both.
    - 3y ago
ortusdux 3y ago
I like to put "Cosmic ray flipped a bit" into bug reports.
- throwaway894345 3y ago
  I used to work as a contractor for John Deere and one of the engineers there would capriciously insist on adding runtime consistency checks in code review because "you never know if lightning might strike or a cosmic ray flips a bit in RAM". This was not for any life-or-death software, it was for the infotainment stuff which was already insanely buggy beginning with the Bosch radio we had sourced and carrying into the ambiguous protocol John Deere designed to speak with the radio and the application code the lowest-bidder contractors wrote before hiring me to fix it (lightning strikes and cosmic rays were the least of their worries). So the radio would fail to connect to many bluetooth devices at the time (because Bosch), the application had no way of telling what state the radio (that it was meant to speak to) was in (because of the faulty protocol), and the application was riddled with other bugs (because lowest-bidder contractors), but by god it was safe from lightning and cosmic rays (except not really because they could just as easily alter the program as the state the program was operating on).
  - MichaelZuo 3y ago
    I don't get the example, it sounds flat out better then doing nothing otherwise.
    - throwaway894345 3y ago
      Well, the alternative was to invest the time into the many glaring concrete bugs rather than hypothetical 'cosmic ray' bit flips. I don't have a fundamental problem with runtime consistency checks if there's some compelling concern and a clear up-front policy for when/where to add them (as opposed to dealing with the whims of a capricious code reviewer).
      - westmeal 3y ago
_joel 3y ago
Would make an interesting increase in RNG entropy ;)

by rrock 3y ago

tudorw 3y ago

annoying, but kind of awesome :)

cshimmin 3y ago

True, but the hot pixels you see in the CCD isn't from bit flips. Rather the CCD is properly doing its job of collecting electrons. It's just that spurious electrons are being produced by the cosmic rays' ionization trail (as opposed to photoelectron in normal operation).

anamexis 3y ago
What's the difference? Aren't bit flips also just spurious electrons being produced by the cosmic rays' ionization trail?
- akiselev 3y ago
  It’s an excitation of the sensor. It may be interpreted somewhat like a bit flip when converted to an image, but it’s normal for image sensors to experience a lot of noise, going back to the days of film. It may just be eliminated by the denoising algorithm like most spurious electrons/photons.
- godelski 3y ago
  Bitflip is when a high energy particle changes the state of a memory address or signal in a wire. Hot pixels are when the CCD (camera sensor) achieves its max level and becomes bright. Pixel overloaded (should also result in spillover). Difference is really just what part of the system receives the energy. For example, you can overload a pixel with a laser, but you also should get spillover. Bit flips tend to be more localized, affecting only one part. In reality, the difference doesn't matter too much, as long as we're keeping our discussion to cosmic events. But also note that images experience a lot of (non-gaussian) noise and plenty of this is from cosmic excitation as well as from other natural and man made sources. Just the levels are a lot lower and unlikely to result in a bitflip (which is a pretty high energy event).
  - cshimmin 3y ago
    Pretty much this. But the point is that a bitflip would be like, your CCD was supposed to read out value 0b00000 = 0 but due to cosmic ray interference, it read out 0b10000 = 16 instead. Instead, what's happening in GGP's experiment is that actual electrons, created in the bulk of the active silicon region by a passing cosmic ray, are getting detected by the CCD, and it will (correctly) read out some value between 00000 and 11111, depending on how many electrons it saw. In principle you can actually make a histogram of these readout values and observe the Bethe-Bloch distribution of energy loss for ionizing particles through the (very thin) bulk of silicon! On the other hand, random bit flips (which are much rarer!) would just give you a random distribution of the numbers {00000, 00001, 00010, 00100, 01000, 10000}.

exitb 3y ago

That’s cool, is that some sort of specialized equipment, or could that observation be replicated by an amateur with a RAW-capable camera?

csdvrx 3y ago
Put a lid on. Continuously take pictures. Look for deltas in the pixel values

tivert 3y ago

>> I've always been hearing that solar flares and the resulting geomagnetic storms pose danger to hard drives and electronics. Is there any truth to it? > Bit flips from cosmic rays. I don't think that's it. IIRC, if a geomagnetic storm/coronal mass ejection is big enough, it can cause certain effects that are similar to an EMP. What the OP is talking about sounds like a distorted version of that danger: a nuclear EMP could directly fry microelectronics, a solar storm is a kind of EMP (solar EMP), but is missing most of the effects that could directly damage microelectronics, and many people conflate the two. https://en.wikipedia.org/wiki/Carrington_Event https://en.wikipedia.org/wiki/Carrington_Event https://en.wikipedia.org/wiki/Electromagnetic_pulse#Types https://en.wikipedia.org/wiki/Electromagnetic_pulse#Types

cronix 3y ago
Yes, but during the Carrington Event, electrical wires became overloaded and blowing out equipment attached to "the grid." I've had a computer blow out (sparks, smoke and everything) due to a power surge when the main power went out and then back on, rapidly. So while the "direct" causes might be different between EMP and CME, the end results are basically the same. I could only imagine what our current (very power sensitive) electronics would do in that scenario. From the wikipedia Carrington Event you posted: > Because of the geomagnetically induced current from the electromagnetic field, telegraph systems all over Europe and North America failed, in some cases giving their operators electric shocks.[22] Telegraph pylons threw sparks.
- tivert 3y ago
  > I've had a computer blow out (sparks, smoke and everything) due to a power surge when the main power went out and then back on, rapidly. > So while the "direct" causes might be different between EMP and CME, the end results are basically the same. Not necessarily. My understanding is a CME solar EMP would take out grid-connected devices (via power surges over the grid), but leave most unconnected devices unharmed (e.g. laptops running on battery), but a nuclear EMP would take out both.
  - 3y ago

ortusdux 3y ago

I like to put "Cosmic ray flipped a bit" into bug reports.

throwaway894345 3y ago
I used to work as a contractor for John Deere and one of the engineers there would capriciously insist on adding runtime consistency checks in code review because "you never know if lightning might strike or a cosmic ray flips a bit in RAM". This was not for any life-or-death software, it was for the infotainment stuff which was already insanely buggy beginning with the Bosch radio we had sourced and carrying into the ambiguous protocol John Deere designed to speak with the radio and the application code the lowest-bidder contractors wrote before hiring me to fix it (lightning strikes and cosmic rays were the least of their worries). So the radio would fail to connect to many bluetooth devices at the time (because Bosch), the application had no way of telling what state the radio (that it was meant to speak to) was in (because of the faulty protocol), and the application was riddled with other bugs (because lowest-bidder contractors), but by god it was safe from lightning and cosmic rays (except not really because they could just as easily alter the program as the state the program was operating on).
- MichaelZuo 3y ago
  I don't get the example, it sounds flat out better then doing nothing otherwise.
  - throwaway894345 3y ago
    Well, the alternative was to invest the time into the many glaring concrete bugs rather than hypothetical 'cosmic ray' bit flips. I don't have a fundamental problem with runtime consistency checks if there's some compelling concern and a clear up-front policy for when/where to add them (as opposed to dealing with the whims of a capricious code reviewer).
    - westmeal 3y ago

_joel 3y ago

Would make an interesting increase in RNG entropy ;)