## DLS 2 years ago Example of any 2 particles which do not exert Gravitational force on each other?

1. DLS

@experimentX @Mashy

2. Mashy

photons? :P

3. DLS

I thought of photon but its not exactly massless..it has SOME mass so negligible..but no 0

4. DLS

timing:D

5. Mashy

ermm.. is it?.. i thought it had no mass :D

6. DLS

$\LARGE M_{p}=1.8 \times 10^{-42}g$

7. Mashy

omg.. :O.. where did you get that from? :O.. anwyays.. there are no particles then without gravity as far as i know :O

8. DLS

if photons dont have mass how do they have momentum?

9. Mashy

that is really more subtle than you think.. when light can act like both particle and wave... which itself is mind boggling.. you think it not having mass but having momentum is a big deal? :P

10. DLS

lol

11. Iamgmg90

You measure gravitational force on particles that's at a quantum level, which involves photons. In QM photons are considered to have a rest mass of 0, so I guess the only answer is photon. Higgs to come?

12. DLS

Higgs is massless?

13. Iamgmg90

DLS look into photoelectric effect derivation and compton scattering

14. Mashy

but you know what?? think of this .. if two photons of light are moving parallel to each other(in vacuum)... if they put force of gravity on each other, then their velocities WOULD CHANGE right.. i don't care how small that change is.. but it would change.. ?? but remember relativity?? light cannot have ANY OTHER speed than C.. in vacuum.. regardless of what crap you do!!.. so they cannot put gravitational force on each other :O hmm.. how is that argument? :O

15. Iamgmg90

for why it has momentum, no higgs would give more knowledge, it gives mass.

16. DLS

i know photoelectric effect

17. Mashy

or maybe not.. you can use general relativity to explain that.. so never mind :D

18. DLS

The Standard Model's explanation of why some fundamental particles have mass when 'naive' theory says Higgs boson should be massless

19. DLS

so can we say photon photon and boson boson :O

20. DLS

@Mashy dude stop showing off relativity in every question of mine when u know i dont understand it :P

21. Iamgmg90

Photoelectric determines relationship between energy and frequency ... E proportional to (a + bw) where w = angular omentum so E = Hbar(w-w_a) = h(v - v_a) photon rest mass is zero for general relation of energy, so it can be written as E^2 = (m_0*c^2)^2 + p^2c^2 = Hbar^2w^2 and can cancel to momentum p = Hbar * k, where k = w/c (wave number) therefore the momentum of a photo can be given as p = Hbar * k bear in mind wave particle duality, how a wave can have momentum is a toughy, yet quite beautiful

22. Mashy

wait for @Iamgmg90 something bombastic is on its way.. either that or his computer is stuck :D

23. Mashy

ok sorry DLS :P.. didn't mean to!

24. Iamgmg90

Bombastic haha, its just my understanding I hope it shed light on the matter, excuse the pun :P

25. DLS

guys im a sweet little cute innocent student :3

26. DLS

simple answers should be awesome :P

27. Iamgmg90

Trying to word equations in english and failing, I don't think quantum mechanics could be simple hehe, are you a student of physics?

28. DLS

29. Iamgmg90

11th grade? I have no idea what that is, I'm English

30. Iamgmg90

is that high school?

31. DLS

kinda

32. Iamgmg90

I think the main part of understand that is knowing planck's constant well

33. Iamgmg90

& the difference between h and hbar

34. DLS

35. DLS

not hbar

36. Iamgmg90

its just h / 2pi

37. Iamgmg90

but not just, very important for its relationship with angular frequency

38. Iamgmg90

omg sorry in those equations w = angular frequency, not momentum

39. DLS

$mvr=\frac{nh}{2\pi}$

40. DLS

:o

41. Iamgmg90

Bohr is far from QM, but orbital win

42. DLS

anyway,thanks guys! ill go with photon for meanwhile :P and/or bosson

43. Mashy

from where Bosson came?? bossons have mass :O !!!

44. DLS
45. DLS

naive theory \m/

46. Mashy

so? it still says higg's particle gives mass!

47. DLS

okay photon :P

48. Mashy

higg's particle has been discovered hello!??

49. DLS

oops I cant give medal to myself D:

50. Mashy

super large hardron collider??

51. DLS

oout off my syllabus :P

52. Mashy

geneva switzerland?? .. 7.7TEV??? hello?!?!

53. DLS

:| thanks everyone