1 trillion frames per second

  • #1
65
8

Main Question or Discussion Point

First I am not sure if this is the correct place to post this thread, but the thread will be about optics, quantum physics and special relativity, so it is a mixed subject.

Please watch this video first:

This technology allows capturing videos at mind blowing 1 trillion fps, which allows us to see how light propagates in slow motion!

It is a fascinating video, my mind was blown away when I watched it, and it left me puzzled over 2 things:

1- Laser beam captured frozen in space:
If you watch the video at 1:40 you can clearly see a photo for a bullet of light captured frozen in space. But according to special relativity we are not supposed to be able to see light (moving at c) frozen in all cases, what am I missing here?!

2- Order of events:
At 9:24 it seems the order of events is reversed! the presenter said:
"it turns out, because we are recording nearly at speed of light, we have strange effects, and Einstein would have loved to see this picture. The order at which events take place in this world appear in the camera with sometimes revered order"
Can someone explain what is going on here? Is causality reversed here?!

Thanks,
 

Answers and Replies

  • #2
Demystifier
Science Advisor
Insights Author
Gold Member
10,910
3,601
If you watch the video at 1:40 you can clearly see a photo for a bullet of light captured frozen in space.
This one is not a photo of real light, it is just a picture generated by computer.
 
Last edited:
  • #3
Vanadium 50
Staff Emeritus
Science Advisor
Education Advisor
2019 Award
24,813
7,820
Please watch this video first:
Translation: Please waste 11 minutes of your time so I don't have to provide a summary.
 
  • #4
65
8
Translation: Please waste 11 minutes of your time so I don't have to provide a summary.
Why wasting your time by reading a summary :wink: 1 video worth a million words.
 
  • Like
Likes Demystifier
  • #5
Nugatory
Mentor
12,857
5,505
Why wasting your time by reading a summary :wink: 1 video worth a million words.
There is a reason why real scientific papers have abstracts.
 
  • Like
Likes bhobba and dextercioby
  • #7
65
8
So no body has an explanation/speculation for the reversed order of events? I though I would find an answer here or at least some ideas.
 
Last edited:
  • #8
3,379
943
This one is not a photo of real light, it is just a picture generated by computer.
That definitely would explain it
'Artistic license'
 
Last edited:
  • #9
It's a matter of phase or relative phase between the light wave and the speed of photography; it can make things look like they are going backward.
 
  • #10
65
8
This one is not a photo of real light, it is just a picture generated by computer.
That definitely would explain it
'Artistic license'
I am sure he didn't mean that it is fake or CGI when he said computer generated. The image is reconstructed from thousands of real images, they basically repeat the even thousands of time and each time they record a photo for very short time, and so very little light will be collected and the images will be very dark, but then they combine all the images and process them in a computer to reconstruct a clear image.
 
Last edited:
  • Like
Likes edguy99
  • #11
272
20
I am sure he didn't mean that it is fake or CGI when he said computer generated. The image is reconstructed from thousands of real images, they basically repeat the even thousands of time and each time they record a photo for very short time, and so very little light will be collected and the images will be very dark, but then they combine all the images and process them in a computer to reconstruct a clear image.
They superpositioned the photographs.

In physics and systems theory, the superposition principle, also known as superposition property, states that, for all linear systems, the net response at a given place and time caused by two or more stimuli is the sum of the responses that would have been caused by each stimulus individually.
 
  • #12
Demystifier
Science Advisor
Insights Author
Gold Member
10,910
3,601
I am sure he didn't mean that it is fake or CGI when he said computer generated. The image is reconstructed from thousands of real images,
No, I think this one isn't reconstructed from real images.
 
  • #13
65
8
So no body has an explanation/speculation for the reversed order of events? I though I would find an answer here or at least some ideas.
I searched about this but I didn't find a definitive answer, however I found 2 Possible explanations in similar question in http://physics.stackexchange.com, I will put them here for info:

"After thinking about the effect, it seems to me that the observed reversal of ripple direction might be due to the tapered neck of the coke bottle. This taper could make for a lesser to-camera travel time for photons headed toward the tapered neck, then the to-camera travel time of photons that are headed for a wider point along the neck. As a result, if two neighboring photons are initially headed forward toward the bottle's cap and then both are scattered, the photon with the shortest in-bottle path length (perhaps the photon that advances further toward the bottle cap) could reach the camera first. This hypothesis would attribute the overall effect to the shape of the bottle, and the differing speeds of light inside and outside the bottle."
curiousStudent

"Stroboscopes are the ideal method for showing aliasing, which occurs in signal processing whenever the frequencies exceed half the acquisition frame rate.
I don't see how the effect shown in the TED Talk is relatavistic. It looks like an aliasing problem to me, though with the data being reconstructed it is hard to say.
"
Peter Diehr
Source: http://physics.stackexchange.com/questions/247022/femtosecond-photography/247051
 

Related Threads on 1 trillion frames per second

Replies
14
Views
653
Replies
3
Views
416
  • Last Post
Replies
9
Views
3K
Replies
0
Views
188
Replies
6
Views
719
Replies
70
Views
4K
Replies
9
Views
883
  • Last Post
Replies
4
Views
691
  • Last Post
Replies
10
Views
782
Top