Earth Mass Increasing? Photons and Photosynthesis making more matter on earth?

Click For Summary

Discussion Overview

The discussion centers on whether the Earth's mass is increasing due to processes involving sunlight, photosynthesis, and the transformation of energy into matter. Participants explore the implications of these processes within the context of thermodynamics and the closed system concept, while also considering the contributions of cosmic debris and the re-radiation of energy.

Discussion Character

  • Debate/contested
  • Exploratory
  • Technical explanation

Main Points Raised

  • Some participants propose that the Earth could be gaining mass through the process of photosynthesis, where plants convert sunlight into chemical energy, potentially leading to an increase in mass.
  • Others argue that plants do not transform sunlight into matter but rather into chemical bonds, and that the Earth is not a closed system, as it exchanges matter with its environment.
  • One participant mentions that the Earth gains mass from cosmic debris, estimating an increase of about 35 million kg per year, while another requests a source for this figure.
  • Several participants discuss the concept of re-radiation of energy, noting that almost all incoming energy from the Sun is re-radiated, with some suggesting that a very small fraction may not be re-radiated during photosynthesis.
  • There is a contention regarding the implications of energy absorption and re-radiation, with some asserting that the energy difference could contribute to mass gain, while others challenge this reasoning.
  • Participants reference historical experiments, such as those by Jan Baptist van Helmont, to illustrate the relationship between soil mass and plant growth.

Areas of Agreement / Disagreement

Participants do not reach a consensus on whether the Earth is gaining mass through photosynthesis or other processes. Multiple competing views remain regarding the nature of mass gain and the implications of energy transformations.

Contextual Notes

Limitations include unresolved assumptions about the definitions of mass gain, the closed system concept, and the specifics of energy re-radiation. The discussion also reflects varying interpretations of historical experiments and their relevance to current claims.

  • #31
thanks for that DH

this isn't my particular field of physics so always willing to learn :)

so, I assume, we aren't even talking about rest mass of a photon, its purely the heating effect caused by the transfer of energy by the absorption of the photon ?

Dave
 
Science news on Phys.org
  • #32
davenn said:
thanks for that DH

this isn't my particular field of physics so always willing to learn :)

so, I assume, we aren't even talking about rest mass of a photon, its purely the heating effect caused by the transfer of energy by the absorption of the photon ?

Dave

Exactly.
 
  • #33
davenn said:
so, I assume, we aren't even talking about rest mass of a photon
Correct.

its purely the heating effect caused by the transfer of energy by the absorption of the photon ?
Incorrect. There's also chemistry. Photosynthesis is an endothermic reaction. The sugars created by photosynthesis are more massive than the masses of the compounds that went into forming those sugars; it's a consequence of an endothermic reaction.
 
  • #34
davenn said:
and further to that ... aren't photons supposed to be massless ?
so isn't it irrelevant to discuss their coming to and going from the Earth causing an addition or loss of mass of the Earth ?
The statement that a photon is massless means that its energy equals its momentum in units where c=1. I.e. The formula for mass in such units is m^2=E^2-p^2. So, if you have an object with m=1 at rest (p=0 and E=1) and it absorbs a photon with E=1 (m=0 and p=1) then by conservation of momentum and energy after the absorption it has E=2 and p=1, which gives m=1.7 So even though a photon is massless another object can still gain mass when it absorbs one.
 

Similar threads

  • · Replies 41 ·
2
Replies
41
Views
4K
Replies
5
Views
8K
  • · Replies 17 ·
Replies
17
Views
2K
  • · Replies 7 ·
Replies
7
Views
2K
Replies
1
Views
3K
  • · Replies 13 ·
Replies
13
Views
3K
  • · Replies 7 ·
Replies
7
Views
3K
  • · Replies 8 ·
Replies
8
Views
7K
  • · Replies 1 ·
Replies
1
Views
4K
  • · Replies 14 ·
Replies
14
Views
2K