3 ms·

I'm curious if anyone knows whether its safe to put a strong EM field so close to your brain, so often — evidence one way or the other. I use a battery powered

I'm curious if anyone knows whether its safe to put a strong EM field so close to your brain, so often — evidence one way or the other. I use a battery powered clipper, in hopes it would have a weaker field than one powered by 120VAC.

steve19 8y ago
What makes you think it's not safe?
- Scoundreller 8y ago
  Probably the increasing evidence about Transcranial magnetic stimulation.
  - zwkrt 8y ago
    As a physics smell test, TMS seems to be performed using quickly releasing a capacitor to create a 1-10 (order of magnitude) Tesla magnetic field over a very short period of time. 10T is similar to the magnetic field generated by an MRI. For comparison, a toaster produces a 100 nano-Tesla field, about 7 orders of magnitude smaller. So supposing TMS causes real effect, the clippers are so weak in comparison that I would think they are harmless. In terms of electricity, which people have more intuition about, 7 orders of magnitude is the difference between a studio camera flash and a lightning strike .
    - ntenenz 8y ago
      Most MRI's are nowhere near 10T. Scanners in hospitals are typically either 1.5T or 3T. 7T exists, but is _extremely_ rare in clinical practice.
      - testvox 8y ago
        TMS is not done with a MRI machine.
      - gpm 8y ago
        This is a good comment, but I think it's worth emphasizing that this is the difference between "7 orders of magnitude" and "6 orders of magnitude". It doesn't in any way invalidate the point in the comment it is replying to.
        zwkrt 8y ago
        Yes I was doing that annoying thing physicists do where if we are off by 100x we consider ourselves to have succeeded greatly.
godot 8y ago
Consider learning to cut your own hair with scissors if your hair type allows it. I've done haircuts for myself for 15 years with only a pair of thinning scissors. I have never once used a clipper. I'm Asian with straight hair so this is possible. The sides and back are hard at first but thinning scissors make the cutting very mistake-tolerant. You can cut at any angle, roughly around the place that needs it, and it cuts some layers of hair off. You just repeat cutting and feeling the length with your hands and eventually it'll be at the right length. It takes me about 30-45 minutes including everything from cutting, showering after, vacuuming and clean up. I only recent stopped (and went back to a barber shop), only because I have a baby now and I really need every bit of energy and time I can get back in my life.

steve19 8y ago

What makes you think it's not safe?

Scoundreller 8y ago
Probably the increasing evidence about Transcranial magnetic stimulation.
- zwkrt 8y ago
  As a physics smell test, TMS seems to be performed using quickly releasing a capacitor to create a 1-10 (order of magnitude) Tesla magnetic field over a very short period of time. 10T is similar to the magnetic field generated by an MRI. For comparison, a toaster produces a 100 nano-Tesla field, about 7 orders of magnitude smaller. So supposing TMS causes real effect, the clippers are so weak in comparison that I would think they are harmless. In terms of electricity, which people have more intuition about, 7 orders of magnitude is the difference between a studio camera flash and a lightning strike .
  - ntenenz 8y ago
    Most MRI's are nowhere near 10T. Scanners in hospitals are typically either 1.5T or 3T. 7T exists, but is _extremely_ rare in clinical practice.
    - testvox 8y ago
      TMS is not done with a MRI machine.
    - gpm 8y ago
      This is a good comment, but I think it's worth emphasizing that this is the difference between "7 orders of magnitude" and "6 orders of magnitude". It doesn't in any way invalidate the point in the comment it is replying to.
      - zwkrt 8y ago
        Yes I was doing that annoying thing physicists do where if we are off by 100x we consider ourselves to have succeeded greatly.

godot 8y ago

Consider learning to cut your own hair with scissors if your hair type allows it. I've done haircuts for myself for 15 years with only a pair of thinning scissors. I have never once used a clipper. I'm Asian with straight hair so this is possible. The sides and back are hard at first but thinning scissors make the cutting very mistake-tolerant. You can cut at any angle, roughly around the place that needs it, and it cuts some layers of hair off. You just repeat cutting and feeling the length with your hands and eventually it'll be at the right length. It takes me about 30-45 minutes including everything from cutting, showering after, vacuuming and clean up. I only recent stopped (and went back to a barber shop), only because I have a baby now and I really need every bit of energy and time I can get back in my life.