# Creation of Matter

1. Jun 4, 2015

### ArmanCham

Lets suppose we have a photon and it will gonna create a particle particle mass is $16.10^-29$ kg.I used $E=mc^2$ to find the solution and I found 90 MeV but the answer is 180 where did I made wrong.

Thanks

Last edited: Jun 4, 2015
2. Jun 4, 2015

### Sagar Singh

particle mass not clear

3. Jun 4, 2015

Staff Emeritus
If you don't show us the calculation, it will be very difficult to tell you where you went wrong.

4. Jun 4, 2015

### ArmanCham

16.10^-29 kgxc^2 is equal 16x9x10^-13 joule=144x10^-13 joule I convert this MeV and I found 90 MeV but the answer is 180MeV

5. Jun 4, 2015

### ChrisVer

I guess because you need 2 particles at the end?

6. Jun 4, 2015

### Sagar Singh

you forget momentum conservation

7. Jun 4, 2015

### ArmanCham

I thought we need two photons to create a particle but I am not sure

8. Jun 4, 2015

Me ?

9. Jun 4, 2015

### Sagar Singh

yaa momentum conservation is must,

10. Jun 4, 2015

### ArmanCham

So final Answer is we need two photon ??

11. Jun 4, 2015

### Sagar Singh

ye
yes

12. Jun 4, 2015

### ChrisVer

I wasn't thinking about 2 photons...rather about 2 particles at the end...
$\gamma \rightarrow 1+2$

13. Jun 4, 2015

### ArmanCham

But theres one particle

14. Jun 4, 2015

### ChrisVer

you can't get 1 massive particle from 1 photon....
Simply because that would violate energy/momentum conservation. For the massive particle you can go to a frame where its momentum vanishes (rest frame)...at that frame, the photon's momentum can't be zero (because momentum=energy for photons, so you would get nothing), and you get a violation of energy/momentum...

15. Jun 4, 2015

Staff Emeritus
We are 15 messages into this, and we don't even have a clear idea on what the question is - people are still trying to guess.

16. Jun 4, 2015

### ArmanCham

The question is we have one photon and it creates a particle we know particle mass but intersting thing is answer says photon energy is twice a particle energy why theres extra energy ?

17. Jun 4, 2015

### ArmanCham

Thats make sense I thought feymann diagram we need one boson and two fermion to make a correct "feymann diagram" there cant be two boson and one fermion.So you are saying 180Mev will create two 90Mev particle or 180 Mev will create 90 Mev particle 90 Mev photon

18. Jun 4, 2015

### ArmanCham

I found the answer I am so so sorry.

19. Jun 4, 2015

Staff Emeritus
Since that never happens on its own, that's clearly not the question.

20. Jun 4, 2015

### ArmanCham

Yeah,the solution is photon makes matter and antimatter but for that we need two photon and two matter.Wait !! Can one photon create two particles ? Or we need at least two photon If we need at least two photon then the answer will be 90 MeV

21. Jun 4, 2015

### ArmanCham

You are right.

22. Jun 4, 2015

### ChrisVer

You need either 2 real photons, or (if you have 1) it will be virtual...

23. Jun 4, 2015

### ArmanCham

γ→e-+e+ my book says this but I know that there must be 2γ

24. Jun 4, 2015

### ChrisVer

I think my previous post answers this...
As an intermediate virtual photon this process is possible or if there are other particles around which can take some energy as well...
For real photons this is not and you need 2γ

25. Jun 4, 2015

### ArmanCham

There where one photon and it cant be virtual photon
Book has false info

thank you.