What Would Happen if High Light Density Hit Water?

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Discussion Overview

The discussion explores the effects of directing a high photon density light package at a volume of water for a brief period, specifically considering scenarios involving concentrated sunlight. Participants examine the potential physical interactions, such as evaporation or atomic excitation, and the relevant timescales involved in these processes.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions what would happen if a high photon density light package, akin to concentrated sunlight, were directed at water for a millisecond, speculating about possible evaporation or explosive gas formation.
  • Another participant asserts that concentrated sunlight would easily vaporize everything it touches, suggesting that the effects would be more pronounced than typical light interactions.
  • Discussion includes the timescale of electromagnetic interactions, with one participant noting that the time scale is on the order of 10-23 seconds, while milliseconds are considered relatively long.
  • Another participant challenges the notion of a fixed interaction timescale, arguing that it depends on the size of the interacting entities, and emphasizes the need to consider the specific context of the interaction.
  • One participant introduces the concept of "ultrafast" or "femtosecond" lasers, indicating that shorter timescales could lead to significant physical phenomena, contrasting with the millisecond timescale discussed by the original poster.

Areas of Agreement / Disagreement

Participants express differing views on the implications of the photon density and the relevant timescales for interactions with water. There is no consensus on the outcomes of such interactions, and the discussion remains unresolved regarding the specific effects of high photon density on water.

Contextual Notes

Participants note that the timescale for interactions is dependent on the size of the entities involved and that the original poster's assumption of a lower threshold time for noticeable effects may not be accurate. The discussion highlights the complexity of photon interactions with matter and the variability of outcomes based on different conditions.

1832vin
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what happens if a high photon density light package was directed to a volume of water for a fraction of a second? what would happen?
i mean what if the whole sun's light is to be shined from the concave lens (pretend the sun only shines on 1 side) i mean, the frequency isn't much higher, so PHOTOelectric effect wouldn really happen... but all those photons onto a volume of water (let's presume all photons makes contact) for a millisecond, would the water evaporate and turn into gas exploding?
is it even possible to energies ATOMS in a small time frame?
 
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what happens if a high photon density light package was directed to a volume of water for a fraction of a second? what would happen?
Same as any light - but more so. Details depend on the type of light.

i mean what if the whole sun's light is to be shined from the concave lens (pretend the sun only shines on 1 side)
Oh that would easily vaporize everything it touches.

is it even possible to energies ATOMS in a small time frame?
The time scale of the electromagnetic dipole interaction is of order 10-23s ... milliseconds is more like 10-3s.
 
Last edited:
Simon Bridge said:
The time scale of the electromagnetic dipole interaction is of order 10-23s ... milliseconds is more like 10-3s.
There is no such thing. The time scale of the interaction is not a property of electromagnetism, but rather the size of the thing it is interacting with. The oft-quoted 10-23 sec is the time it takes light to travel 1 fermi, and is therefore the minimum time it takes for anything to interact with a nucleon.
 
Thanks for the clarification. Timescale does indeed depend on the thing under consideration.
10-18s to cross an atom for eg. we can also talk about the mean-time to ionize a sample given the flux etc etc etc.
Properly the "size" should be the crossection - which does depend on the interaction.

... but OP was talking about the total output from the Sun here so I figured the nuclear interaction oom figure was appropriate here.

The question before us is whether there is sufficient time for the entire photon flux from the Sun, concentrated on "some water" to "excite the atoms". The point I'm trying to make is that the sort of time thought of as "small" (milliseconds) is actually very large.

We could ask what would constitute a time period so small that there would be no noticeable effect I suppose.
I think OP is under the impression that there is a lower threshold time in which nothing would happen.
 
On a millisecond timescale, you probably would not get much happening.

On shorter timescales though... look up "ultrafast" or "femtosecond" lasers to see a huge, diverse amount of physics on light propagation through solids/fluids.

Claude.
 

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