Why is milk smoother and flatter than water?

  • Context: Undergrad 
  • Thread starter Thread starter Jorgen1224
  • Start date Start date
  • Tags Tags
    Laser Optics Water
Click For Summary

Discussion Overview

The discussion revolves around the optical properties of milk compared to water, particularly focusing on why milk appears smoother and flatter than water when subjected to laser projection experiments. Participants explore the implications of molecular structure and scattering effects, as well as the experimental setup and conditions.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested, Experimental/applied

Main Points Raised

  • One participant describes an experiment using a laser to observe speckles on milk and water, noting that speckles are less visible in milk, which they attribute to the optical properties of milk.
  • Another participant suggests that the complexity of milk's molecular structure, particularly the fat content, may contribute to its optical characteristics compared to water.
  • One participant expresses skepticism about the experimental design, questioning whether dyed water can be considered equivalent to dyed milk and suggesting that specific gravity differences could affect results.
  • A later reply challenges the clarity of the initial participant's observations regarding the speckles and their implications about "flatness."

Areas of Agreement / Disagreement

Participants do not reach consensus on the validity of the experimental setup or the conclusions drawn from it. There are competing views on the interpretation of the results and the factors influencing the observed phenomena.

Contextual Notes

Participants note potential confounding factors in the experiment, such as differences in specific gravity between milk and water, and the need for clearer definitions of terms like "flatness" and "speckles."

Who May Find This Useful

Individuals interested in optics, the physical properties of liquids, and experimental physics may find this discussion relevant.

Jorgen1224
Messages
36
Reaction score
0
I have conducted an experiment involving projecting a laser beam onto a surface and observing speckles that move relative to us. Those speckles become less visible (maybe smaller?) when the surface is smooth and that is especially the case with milk. I have dyed milk and water to see whether in both of these substances speckles appear and they do, but only in a sample with water. They are barely visible, but everyone in my group agrees that they are still apparent and we don't understand why.There is not a lot of information about these aspects of milk on the internet yet I found this "Skim milk appears slightly blue because casein micelles scatter the shorter wavelengths of visible light (blue) more than the red." [https://www.uoguelph.ca/foodscience/book-page/physical-properties-milk].

Milk was 3.2% fat
Laser: 532nm and about 100mW
I used black fabric dye and made sure that it mixed well. While it made water totally black, milk became dark blue.

I posted it here since I'm not sure whether it's more about optics or particle physics.
 
Physics news on Phys.org
The molecules in milk, mostly fat, are much more complicated than water molecules. They wrap together and link together much more than water molecules.
 
I'm not convinced this is a fair test.
I'm not convinced that dyed water is equivalent to dyed milk in terms of the conditions being tested.

Just one spurious example: I'll bet the specific gravity of the water is not the same as the milk.

You could repeat the experiment, and refine the conditions, eliminating confounding factors until you found one factor that is the crux. As HoI suggests, the proteins and fats are likely the cause.

I'm also not convinced that your conclusion about "flatness" makes sense. But maybe I don't understand your setup. Are the speckles you refer to reflections off the surface?
 
Jorgen1224 said:
I have dyed milk and water to see whether in both of these substances speckles appear and they do, but only in a sample with water.

That is not at all clear.
 

Similar threads

Undergrad Why is the observed local region of space flat?
  • · Replies 25 ·
Replies
25
Views
3K
Graduate Birefringence and Automotive Window Tinting
  • · Replies 9 ·
Replies
9
Views
9K