It's not 100% same effect, just idea you may want to dig deeper:
1. Create file with white background
2. Grab Gradient tool and set it like here:

3. now just experiment and drag in different directions


until you will get something like this:

4. Desaturate the image Image > Adjustments > Desaturate (Cmd(or Ctrl) + Shift + U )
5. Blur it

6. Add some motion with Filter > Displace > Wave

7. Add new Gradient Map in the layers panel and pick the gradient from attachment of this post:

8. For now it should look more ore less like this:

9. Duplicate bottom layer and put it at the top of layers stack with blend mode set to screen
10. Create levels adjustment layer below gradient map adjustment


11. Mask using brush tool with black color

12. Final result is something like this:
