Conservation of Energy: Where Did Energy Originate?

Click For Summary

Discussion Overview

The discussion revolves around the origins of energy in the context of the conservation of energy principle, exploring theoretical implications and interpretations related to cosmology and the Big Bang. Participants engage in clarifying concepts of energy and its application in physical systems.

Discussion Character

  • Exploratory
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants question the understanding of energy before discussing its origins, suggesting that clarity on the definition of energy is crucial for the conversation.
  • One participant proposes that the universe only existed after t=0, implying that discussing energy before the Big Bang may be nonsensical, although they acknowledge the possibility of discussing conditions approaching that moment.
  • Another participant defines energy as the capacity of a physical system to perform work, emphasizing that the amount of energy is dependent on the state of the system, including factors like particle placement and velocity.
  • It is suggested that energy could have been created at the birth of the universe or that it may have always existed, leaving open the question of energy's origins.
  • One participant argues that conservation of energy does not apply on a cosmological scale, citing the redshift of light from distant galaxies as evidence that energy can be lost in the universe as a whole.
  • A later reply questions whether the implications of energy conservation on a cosmological scale could allow for the creation of energy in terms of galaxies as a whole.

Areas of Agreement / Disagreement

Participants express differing views on the origins of energy and the applicability of conservation laws on cosmological scales. No consensus is reached regarding the implications of these discussions.

Contextual Notes

Participants acknowledge the complexity of discussing energy in relation to the universe's origins and the limitations of applying conservation principles universally. The discussion remains open-ended regarding definitions and implications.

PFCalvin
Messages
9
Reaction score
0
Hey guys. I was wondering, if energy cannot be created or destroyed as stated in the conversation of energy, then where did energy come from in the first place?
 
Physics news on Phys.org
Before we get into a discussion on where the energy was created, do you know what energy is? I only ask because this is going to go nowhere if you don't know what energy is.
 
Drakkith said:
Before we get into a discussion on where the energy was created, do you know what energy is? I only ask because this is going to go nowhere if you don't know what energy is.

This. Also, no one knows completely for sure, but my view is that the Universe only existed after t=0, and so it's absurd to talk about at the instant of the Big Bang or before (though we can talk about approaching the instant of the BB, in which case all the energy was around.)
 
Well. We know that energy is the observed quantity that one physical system is able to do work on another physical system. Correct me if I'm wrong.
 
PFCalvin said:
Well. We know that energy is the observed quantity that one physical system is able to do work on another physical system. Correct me if I'm wrong.

Pretty much correct. So given that energy is the ability to perform work, this suggests that the amount of energy something has is dependent on the state of each system, as in the placement of the particles and their respective velocities, charges, etc. For example a falling rock of 0.1 kg will do far less work (and thus have less energy) than a rock of 10 kg that falls at the same speed. However, falling rocks are either lifted up there, requiring work and energy, or they already existed previously.

The ultimate answer to your question is twofold. First, the creation or birth or whatever you want to call it of the universe is one possible way to create energy (maybe). Unless it has always existed of course, in which case energy has always existed as well. The second thing is that conservation of energy does NOT apply on the cosmological scale, which is where we get into talking about the universe as a whole. Consider this. Galaxies not bound to us are moving away from us. This causes a redshift in their light that reaches us. Now, unlike a moving light bulb here on Earth, these galaxies are NOT moving towards anything else, from their frame of reference all other galaxies are moving away from them as well, thus their light is completely redshifted in all directions. This means that all of the light that is sent out is losing energy from redshift. So conservation of energy does not apply to the universe as a whole, but only to local areas.
 
Drakkith said:
Pretty much correct. So given that energy is the ability to perform work, this suggests that the amount of energy something has is dependent on the state of each system, as in the placement of the particles and their respective velocities, charges, etc. For example a falling rock of 0.1 kg will do far less work (and thus have less energy) than a rock of 10 kg that falls at the same speed. However, falling rocks are either lifted up there, requiring work and energy, or they already existed previously.

The ultimate answer to your question is twofold. First, the creation or birth or whatever you want to call it of the universe is one possible way to create energy (maybe). Unless it has always existed of course, in which case energy has always existed as well. The second thing is that conservation of energy does NOT apply on the cosmological scale, which is where we get into talking about the universe as a whole. Consider this. Galaxies not bound to us are moving away from us. This causes a redshift in their light that reaches us. Now, unlike a moving light bulb here on Earth, these galaxies are NOT moving towards anything else, from their frame of reference all other galaxies are moving away from them as well, thus their light is completely redshifted in all directions. This means that all of the light that is sent out is losing energy from redshift. So conservation of energy does not apply to the universe as a whole, but only to local areas.

If what you are saying is true, does this mean that in terms of galaxies as a whole, I can create energy?
 

Similar threads

High School Ignoring the motion of the Earth for energy vs. momentum conservation
  • · Replies 21 ·
Replies
21
Views
2K
High School Why Do Objects Bounce? Exploring Momentum and Energy Conservation
  • · Replies 6 ·
Replies
6
Views
2K
High School Can conservation laws take time to obey?
  • · Replies 1 ·
Replies
1
Views
1K
High School Conservation of Energy: Ball on a U-Shaped Ramp
  • · Replies 2 ·
Replies
2
Views
941
High School Energy needed to raise an object to a certain altitude
  • · Replies 7 ·
Replies
7
Views
2K
Undergrad What Explains the Paradox of Mechanical Energy Conservation?
  • · Replies 9 ·
Replies
9
Views
2K
Undergrad Seemingly a contradiction of conservation of energy?
  • · Replies 51 ·
2
Replies
51
Views
5K
High School Work Done By Conservative Forces
  • · Replies 1 ·
Replies
1
Views
2K
Undergrad Conservation of Energy and a billiard ball
  • · Replies 20 ·
Replies
20
Views
18K
High School Conservation of momentum and conservation of energy details
  • · Replies 30 ·
2
Replies
30
Views
3K