system
Given the following post, respond as if you're commenting on Reddit:
human
Has a gravitational force been observed between massless particles?

Light is attracted to mass by gravity (black holes, gravitational lensing). Due to Newton's 3rd law (For every action, there is an equal and opposite reaction) the light will assert a force on the mass via gravity. Extending this, is a gravitational force between photons? And is it large enough to be observed?


I understand at high energies, pair production will be a factor, but I was thinking about lower energies than this. 



Additional question: If you shine two lasers of wavelength X metres in parallel, Y metres apart, how long will it before the beams converge due to gravity.


I'm not sure about my logic here. Please correct me if I'm wrong.
gpt
> Extending this, is a gravitational force between photons? 

Yes, if they are not perfectly parallel (that also answers your last question).

> And is it large enough to be observed?

Not with today's technology, and not with any planned or even proposed experiment.