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I love my Apple Watch ultra, because with cellular I can use it as a phone – a very lightweight phone without social media distractions. But I have to say I am

I love my Apple Watch ultra, because with cellular I can use it as a phone – a very lightweight phone without social media distractions. But I have to say I am a little bit uneasy about having a cellphone strapped to my arm. Someone with physics knowledge please calm me down?

ecmascript 3y ago
I have a Samsung watch without cellular but with bluetooth communications instead. Can someone eloborate what the difference is between celluar connections and other wireless tech like headless phones or watches? Is there any difference except strength etc. Never believed it before, but suddently the thought of wireless technologies being bad gave me a reality check and I realized I have never questioned it.
- mceachen 3y ago
  Bluetooth is also non-ionizing. The frequency is close frequency to WiFi: https://en.m.wikipedia.org/wiki/Bluetooth#Health_concerns https://en.m.wikipedia.org/wiki/Bluetooth#Health_concerns
- wkat4242 3y ago
  There's a difference mainly in "strength" (transmit power). The frequencies and modulations used are not all that different. In terms of radio energy, bluetooth is the lowest, then wifi and then cellular.
dotnet00 3y ago
Probably not the kind of physics knowledge you're expecting, but your regular phone probably also tends to be "tied" to your thigh in your pocket or to your hand when in use. If that's fine with you (weight and distraction concerns aside), a watch isn't that different.
cmsj 3y ago
EM radiation striking your body is essentially just going to impart energy into your atoms/molecules. All of the EM radiation emitted by a phone is very very far down in the non-ionising range. That means it can't directly damage the atoms/molecules in your body, it will just be heating those atoms/molecules a bit. Wifi is 2.4GHz, 5GHz or 6GHz Bluetooth is 2.4GHz 3G/4G/5G are in the same kinda range, with the exception of mmWave 5G which is up around 30GHz. Infrared starts around 300GHz, then there's the whole visible light spectrum, and it's only once you get into ultra-violet around 3PHz (yes, Petahertz) that you reach the ionising band, where the radiation imparts enough energy into your constituent atoms/molecules that electrons are broken free. These free electrons will then damage your cells/DNA. So far, there is no evidence that anything in the parts of the spectrum that are licensed for phones/wifi/bluetooth/etc are at all dangerous to humans.
xoa 3y ago
>Someone with physics knowledge please calm me down? All radio is non-ionizing EM, far lower frequency then visible light, thermal, etc. UV, Xrays, and gamma rays are in the opposite direction, higher frequency. Radio cannot do anything except minor amounts of heating, and at milliwatts of transmission power and inverse square law that's REALLY minor amounts of heating. There is no link to any sort of health effects from indirect distant exposure by far, far stronger things like radar or people working at AM/FM radio transmitters, nor any plausible theoretical one (though of course one should be careful with raw high power stuff that could create enough heat to cook, as well as the high voltage components that power it). Just in terms of natural exposure we face endless things that cause vastly stronger thermal effects. I don't know if that's enough to calm you down, or if the entire planet going to massive wireless usage in the span of a decade and over a decade later no discernible significant related physical health effects (mental/social effects aside here, which are real but software not hardware) makes you feel better, but if nothing else don't get scammed by people who lump all "RADIATION!!" together as if the photoelectric effect and quantum mechanics was never discovered. Nor get hyperfocused on some specific tiny but "new" seeming device while ignoring the ginormously bigger ones around you take for granted and never think about (rightly in most cases).
- garyfirestorm 3y ago
  Sun! It emits far more radiation than anything else and we don’t care about walking in sunlight.
  - h1fra 3y ago
    Well tbh sun is responsible for millions of skin cancer every year
  - lxgr 3y ago
    That argument is actually the same error that GP criticizes: Wavelength (i.e. quantized energy) matters a lot. Being irradiated by hundreds of watts of direct sunlight is fine for a short while (and causes skin cancer in the long term!), hundreds of watts of microwave radiation for the same duration is already pretty bad, and the only good thing about hundreds of watts of hard gamma radiation is that you don't have to worry about the long-term effects too much. With mobile devices, we're talking about dozens or at most hundreds of milliwatts of microwave radiation though; there might be some effect, but I personally doubt it would be significant enough to worry about – earlier cell phones used way higher power levels, and I'm not aware of any link to cancer there. And they've been around for a while! Last time I read up on it, the heating effect of holding any metal or plastic slab to the side of your head dominates any additional heat transfer from the EM radiation, even for fairly deep tissues.
mmiyer 3y ago
Worry far more about the sun: "Hence, a cell phone cannot transmit more than 0.125 Watts of energy to your head, while sunlight will transmit 43.8 W. This means that sunlight heats your head 350 times faster than a cell phone. In fact, since sunlight is a much higher frequency than cell phones, the sunlight energy is more dangerous (see Equation [1])." 1. https://www.antenna-theory.com/tutorial/cancer/cellphone.php#:~:text=Hence%2C%20a%20cell%20phone%20cannot,faster%20than%20a%20cell%20phone https://www.antenna-theory.com/tutorial/cancer/cellphone.php....
ngai_aku 3y ago
Nothing about the ultra has changed that fact that you still have to own an iPhone to pair it with, right? It can’t really be considered an independent device?
- mceachen 3y ago
  It has an esim and cellular connectivity, so you can leave your phone home on an outing, but there are things you can configure on your watch only when paired with an iPhone.
agmm 3y ago
At the present, we don't have enough evidence to be concerned about low-power EM radiation. However, this does not rule out the possibility that in the future, we might find a causal link between that kind of radiation and adverse health outcomes. What we do know at the moment is that this type of radiation can heat tissues. What are the long-term biological consequences of that? We don't really know. My advice: try to minimize your exposure out of caution, but don't get too worried about it.
- Schiendelman 3y ago
  If you want caution on something WITH a causal link - don’t eat cooked food!
  - agmm 3y ago
    Just to be clear, I don't think that low-power EM radiation poses a health risk. I am just saying that if you are worried about it (like OP is) you can simply reduce your exposure to it. Doing so is relatively easy and has a minimal quality of life impact. As others have mentioned, low-power EM radiation in the frequency range used by cellphones is non-ionizing, so it can't cause cancer or severe health issues in the same way that ionizing radiation can.
    - Schiendelman 3y ago
      My point is that if OP cares about those risks, they'd prioritize other higher risks first, and they'd run out of quality of life long before they got to this one.
6510 3y ago
As a chain smoker I'd say: don't worry about it.
dpedu 3y ago
> The World Health Organization states on its website that following a large number of studies that "no adverse health effects have been established as being caused by mobile phone use". https://www.france24.com/en/europe/20230912-france-orders-apple-to-halt-iphone-12-sales-due-to-high-radiation-levels https://www.france24.com/en/europe/20230912-france-orders-ap... https://www.who.int/news-room/fact-sheets/detail/electromagnetic-fields-and-public-health-mobile-phones#:~:text=A%20large%20number%20of%20studies,caused%20by%20mobile%20phone%20use https://www.who.int/news-room/fact-sheets/detail/electromagn....

ecmascript 3y ago

I have a Samsung watch without cellular but with bluetooth communications instead. Can someone eloborate what the difference is between celluar connections and other wireless tech like headless phones or watches? Is there any difference except strength etc. Never believed it before, but suddently the thought of wireless technologies being bad gave me a reality check and I realized I have never questioned it.

mceachen 3y ago
Bluetooth is also non-ionizing. The frequency is close frequency to WiFi: https://en.m.wikipedia.org/wiki/Bluetooth#Health_concerns https://en.m.wikipedia.org/wiki/Bluetooth#Health_concerns
wkat4242 3y ago
There's a difference mainly in "strength" (transmit power). The frequencies and modulations used are not all that different. In terms of radio energy, bluetooth is the lowest, then wifi and then cellular.

dotnet00 3y ago

Probably not the kind of physics knowledge you're expecting, but your regular phone probably also tends to be "tied" to your thigh in your pocket or to your hand when in use. If that's fine with you (weight and distraction concerns aside), a watch isn't that different.

cmsj 3y ago

EM radiation striking your body is essentially just going to impart energy into your atoms/molecules. All of the EM radiation emitted by a phone is very very far down in the non-ionising range. That means it can't directly damage the atoms/molecules in your body, it will just be heating those atoms/molecules a bit. Wifi is 2.4GHz, 5GHz or 6GHz Bluetooth is 2.4GHz 3G/4G/5G are in the same kinda range, with the exception of mmWave 5G which is up around 30GHz. Infrared starts around 300GHz, then there's the whole visible light spectrum, and it's only once you get into ultra-violet around 3PHz (yes, Petahertz) that you reach the ionising band, where the radiation imparts enough energy into your constituent atoms/molecules that electrons are broken free. These free electrons will then damage your cells/DNA. So far, there is no evidence that anything in the parts of the spectrum that are licensed for phones/wifi/bluetooth/etc are at all dangerous to humans.

xoa 3y ago

>Someone with physics knowledge please calm me down? All radio is non-ionizing EM, far lower frequency then visible light, thermal, etc. UV, Xrays, and gamma rays are in the opposite direction, higher frequency. Radio cannot do anything except minor amounts of heating, and at milliwatts of transmission power and inverse square law that's REALLY minor amounts of heating. There is no link to any sort of health effects from indirect distant exposure by far, far stronger things like radar or people working at AM/FM radio transmitters, nor any plausible theoretical one (though of course one should be careful with raw high power stuff that could create enough heat to cook, as well as the high voltage components that power it). Just in terms of natural exposure we face endless things that cause vastly stronger thermal effects. I don't know if that's enough to calm you down, or if the entire planet going to massive wireless usage in the span of a decade and over a decade later no discernible significant related physical health effects (mental/social effects aside here, which are real but software not hardware) makes you feel better, but if nothing else don't get scammed by people who lump all "RADIATION!!" together as if the photoelectric effect and quantum mechanics was never discovered. Nor get hyperfocused on some specific tiny but "new" seeming device while ignoring the ginormously bigger ones around you take for granted and never think about (rightly in most cases).

garyfirestorm 3y ago
Sun! It emits far more radiation than anything else and we don’t care about walking in sunlight.
- h1fra 3y ago
  Well tbh sun is responsible for millions of skin cancer every year
- lxgr 3y ago
  That argument is actually the same error that GP criticizes: Wavelength (i.e. quantized energy) matters a lot. Being irradiated by hundreds of watts of direct sunlight is fine for a short while (and causes skin cancer in the long term!), hundreds of watts of microwave radiation for the same duration is already pretty bad, and the only good thing about hundreds of watts of hard gamma radiation is that you don't have to worry about the long-term effects too much. With mobile devices, we're talking about dozens or at most hundreds of milliwatts of microwave radiation though; there might be some effect, but I personally doubt it would be significant enough to worry about – earlier cell phones used way higher power levels, and I'm not aware of any link to cancer there. And they've been around for a while! Last time I read up on it, the heating effect of holding any metal or plastic slab to the side of your head dominates any additional heat transfer from the EM radiation, even for fairly deep tissues.

mmiyer 3y ago

Worry far more about the sun: "Hence, a cell phone cannot transmit more than 0.125 Watts of energy to your head, while sunlight will transmit 43.8 W. This means that sunlight heats your head 350 times faster than a cell phone. In fact, since sunlight is a much higher frequency than cell phones, the sunlight energy is more dangerous (see Equation [1])." 1. https://www.antenna-theory.com/tutorial/cancer/cellphone.php#:~:text=Hence%2C%20a%20cell%20phone%20cannot,faster%20than%20a%20cell%20phone https://www.antenna-theory.com/tutorial/cancer/cellphone.php....

ngai_aku 3y ago

Nothing about the ultra has changed that fact that you still have to own an iPhone to pair it with, right? It can’t really be considered an independent device?

mceachen 3y ago
It has an esim and cellular connectivity, so you can leave your phone home on an outing, but there are things you can configure on your watch only when paired with an iPhone.

agmm 3y ago

At the present, we don't have enough evidence to be concerned about low-power EM radiation. However, this does not rule out the possibility that in the future, we might find a causal link between that kind of radiation and adverse health outcomes. What we do know at the moment is that this type of radiation can heat tissues. What are the long-term biological consequences of that? We don't really know. My advice: try to minimize your exposure out of caution, but don't get too worried about it.

Schiendelman 3y ago
If you want caution on something WITH a causal link - don’t eat cooked food!
- agmm 3y ago
  Just to be clear, I don't think that low-power EM radiation poses a health risk. I am just saying that if you are worried about it (like OP is) you can simply reduce your exposure to it. Doing so is relatively easy and has a minimal quality of life impact. As others have mentioned, low-power EM radiation in the frequency range used by cellphones is non-ionizing, so it can't cause cancer or severe health issues in the same way that ionizing radiation can.
  - Schiendelman 3y ago
    My point is that if OP cares about those risks, they'd prioritize other higher risks first, and they'd run out of quality of life long before they got to this one.

6510 3y ago

As a chain smoker I'd say: don't worry about it.

dpedu 3y ago

> The World Health Organization states on its website that following a large number of studies that "no adverse health effects have been established as being caused by mobile phone use". https://www.france24.com/en/europe/20230912-france-orders-apple-to-halt-iphone-12-sales-due-to-high-radiation-levels https://www.france24.com/en/europe/20230912-france-orders-ap... https://www.who.int/news-room/fact-sheets/detail/electromagnetic-fields-and-public-health-mobile-phones#:~:text=A%20large%20number%20of%20studies,caused%20by%20mobile%20phone%20use https://www.who.int/news-room/fact-sheets/detail/electromagn....