3 ms·
I've always been curious: I understand that h.nu from cell phone radiation isn't big enough to ionize (say) DNA, but since the molecules in our body are in ther
by donovanr 10y ago
I've always been curious: I understand that h.nu from cell phone radiation isn't big enough to ionize (say) DNA, but since the molecules in our body are in thermal equilibrium, can't h.nu + kT get it done every once in a while?
[edited because using an asterisk to denote multiplication was a bad idea]
- tiplus 10y agokT is very little energy compared to a chemical bond. Take for example [0], they give an excitation energy for water of about 8 electron Volts which is ~750 kJ/mol, whereas kT at room temp is about 2.5 kJ/mol. [0] http://scitation.aip.org/content/aip/journal/jcp/128/10/10.1063/1.2837827 http://scitation.aip.org/content/aip/journal/jcp/128/10/10.1...
- donovanr 10y agoRight, but it's the 'every once in a while" part that I wonder about, i.e. the variance of that distribution. Maybe you could argue that since the Maxwell-Boltzmann distribution is narrower the lower its mean, if kT is small then it's an exponentially tiny effect.
- tiplus 10y agoSo yes, kT is small on average (does fluctuate) and it is also 1 kT per degree of freedom. So yes, in principle a few hundreds of atoms could randomly fluctuate in energy to create this effect. However, this is hyper unlikely. I would be suprisd if it happened once in the life time of the universe. Also consider that you cannot create Maxwell demons[1]. [1] https://en.m.wikipedia.org/wiki/Maxwell%27s_demon https://en.m.wikipedia.org/wiki/Maxwell%27s_demon