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Apparently you have not had an MRI or studied MRI. 1) The people operating the MRI are outside the magnetic field. 2) The patient in the MRI is oriented such

Apparently you have not had an MRI or studied MRI. 1) The people operating the MRI are outside the magnetic field. 2) The patient in the MRI is oriented such that the magnetic field is directed from head to toe (where the effect on sensing apparatus in place which might detect earth's magnetic field while standing or sitting would be approximately zero, no matter the magnetic strength). 3) Instructions for the patient in the MRI are to remain as still as possible to reduce imaging noise. So, most patients do not move their head much at all. I'm sorry you seem to be unwilling to even consider the physics, and apparently didn't bother to look at the second reference. I am also sorry that I am having trouble explaining concepts that most biomedical engineers readily understand as the reasons why "but MRI!" is not a valid argument. Regardless, I hope you have a wonderful weekend.

Retric 2y ago
> The people operating the MRI are outside the magnetic field. That’s not how magnetic fields work. It’s not some sci-fi force field that cuts off instantly, the field drops off quickly but it doesn’t disappear. Which is why as mentioned in your second link workers noticed the effect. > unwilling to even consider the physics Again, you’re seemingly unaware of the actual physics involved. MRI’s operate via two different electromagnets which create magnetic fields. A really strong one which is on 24/7, and a separate field which is turned off and on in operation and thus doesn’t correlate with earths magnetic field. So when you walk up to the machine you’re “in” the same giant field just as when you’re inside the machine (or even sitting in some other room in the hospital if we want to be pedantic). This is why it’s relatively common for chairs etc to be yanked across the room and smack into the machines. And thus, if people could directly sense the orientation of earths magnetic field, being anywhere near an MRI would be a really obvious and novel experience.
- daveguy 2y ago
  Oh good, they noticed the effect too. It's almost as if many people experience the effect, but somehow to you it's impossible for any humans to be able to take advantage of the effect at lower field strengths. When you walk up to the machine it's not turned on. Then non-participants go to the small enclosed control room and then the magnet is activated. Every time you respond you reveal how little you know about MRI and weaken your case. You should stop while you are behind. Also, you should lookup faraday cage. They're like magic to someone who has never heard of them, and they're used in MRI control rooms. I feel sorry for your apparent inability to accept you might be ignorant about anything. I hope you grow out of it one day. Enjoy your weekend, I won't be responding again.
  - Retric 2y ago
    > When you walk up to the machine it's not turned on. False. MRI: https://mriquestions.com/is-field-ever-turned-off.html https://mriquestions.com/is-field-ever-turned-off.html Permanent magnet scanners are permanently "on" by definition. Resistive electromagnet scanners, in theory, can be turned on and off. However, it may take 30-60 minutes for their magnetic fields to stabilize after being off and hence they are generally left continuously on during daily operations. To save electricity, they are usually turned off or have their power levels reduced after hours. Superconducting scanners remain on at all times as long as superconducting temperatures are maintained. The main field may be ramped down for servicing in a controlled manner with minimal loss of cryogens in about 30 minutes and restored in a few hours, but this is performed only occasionally. In the event of an emergency, all superconducting scanners have a "quench" button that releases liquid helium into the atmosphere and turns their fields off within a few seconds. Dumping that helium is inherently expensive and only done in a serious emergency. “Faraday cages cannot block stable or slowly varying magnetic fields, such as the Earth's magnetic field (a compass will still work inside one).” https://en.wikipedia.org/wiki/Faraday_cage https://en.wikipedia.org/wiki/Faraday_cage > then the magnet is activated A magnet not THE primary one. Here’s a reasonable though simplified explanation of why there’s multiple magnets involved: https://www.youtube.com/watch?v=NlYXqRG7lus https://www.youtube.com/watch?v=NlYXqRG7lus Anyway, it’s clear you have many fundamental misunderstandings so I can see how you’d come to such wildly inaccurate conclusions. > it's impossible for any humans to be able to take advantage of the effect at lower field strengths. The actual literature investigating the effect describes why it doesn’t work on earths magnetic field.
    - daveguy 2y ago
      Someone who does not know that MRI has variable field strength is someone who truly does not know the basics of MRI. Maybe this source will clue you in as to why your understanding of MRI is fundamentally flawed: https://pmc.ncbi.nlm.nih.gov/articles/PMC4632105/ https://pmc.ncbi.nlm.nih.gov/articles/PMC4632105/ Good luck buddy.
      - Retric 2y ago

Retric 2y ago

> The people operating the MRI are outside the magnetic field. That’s not how magnetic fields work. It’s not some sci-fi force field that cuts off instantly, the field drops off quickly but it doesn’t disappear. Which is why as mentioned in your second link workers noticed the effect. > unwilling to even consider the physics Again, you’re seemingly unaware of the actual physics involved. MRI’s operate via two different electromagnets which create magnetic fields. A really strong one which is on 24/7, and a separate field which is turned off and on in operation and thus doesn’t correlate with earths magnetic field. So when you walk up to the machine you’re “in” the same giant field just as when you’re inside the machine (or even sitting in some other room in the hospital if we want to be pedantic). This is why it’s relatively common for chairs etc to be yanked across the room and smack into the machines. And thus, if people could directly sense the orientation of earths magnetic field, being anywhere near an MRI would be a really obvious and novel experience.

daveguy 2y ago
Oh good, they noticed the effect too. It's almost as if many people experience the effect, but somehow to you it's impossible for any humans to be able to take advantage of the effect at lower field strengths. When you walk up to the machine it's not turned on. Then non-participants go to the small enclosed control room and then the magnet is activated. Every time you respond you reveal how little you know about MRI and weaken your case. You should stop while you are behind. Also, you should lookup faraday cage. They're like magic to someone who has never heard of them, and they're used in MRI control rooms. I feel sorry for your apparent inability to accept you might be ignorant about anything. I hope you grow out of it one day. Enjoy your weekend, I won't be responding again.
- Retric 2y ago
  > When you walk up to the machine it's not turned on. False. MRI: https://mriquestions.com/is-field-ever-turned-off.html https://mriquestions.com/is-field-ever-turned-off.html Permanent magnet scanners are permanently "on" by definition. Resistive electromagnet scanners, in theory, can be turned on and off. However, it may take 30-60 minutes for their magnetic fields to stabilize after being off and hence they are generally left continuously on during daily operations. To save electricity, they are usually turned off or have their power levels reduced after hours. Superconducting scanners remain on at all times as long as superconducting temperatures are maintained. The main field may be ramped down for servicing in a controlled manner with minimal loss of cryogens in about 30 minutes and restored in a few hours, but this is performed only occasionally. In the event of an emergency, all superconducting scanners have a "quench" button that releases liquid helium into the atmosphere and turns their fields off within a few seconds. Dumping that helium is inherently expensive and only done in a serious emergency. “Faraday cages cannot block stable or slowly varying magnetic fields, such as the Earth's magnetic field (a compass will still work inside one).” https://en.wikipedia.org/wiki/Faraday_cage https://en.wikipedia.org/wiki/Faraday_cage > then the magnet is activated A magnet not THE primary one. Here’s a reasonable though simplified explanation of why there’s multiple magnets involved: https://www.youtube.com/watch?v=NlYXqRG7lus https://www.youtube.com/watch?v=NlYXqRG7lus Anyway, it’s clear you have many fundamental misunderstandings so I can see how you’d come to such wildly inaccurate conclusions. > it's impossible for any humans to be able to take advantage of the effect at lower field strengths. The actual literature investigating the effect describes why it doesn’t work on earths magnetic field.
  - daveguy 2y ago
    Someone who does not know that MRI has variable field strength is someone who truly does not know the basics of MRI. Maybe this source will clue you in as to why your understanding of MRI is fundamentally flawed: https://pmc.ncbi.nlm.nih.gov/articles/PMC4632105/ https://pmc.ncbi.nlm.nih.gov/articles/PMC4632105/ Good luck buddy.
    - Retric 2y ago