# Which processes are posible and why?

• Ene Dene
In summary, the conversation discusses the interaction between a photon and a motionless electron, as well as the interaction between a fast positron and a motionless electron. It is determined that the first process is not possible because the energy of the electron would exceed its rest mass, while the second process is not possible because there is no center of mass system for a single photon.
Ene Dene
1. Photon runs into motionless electron and gives the electron all of its energy
2. Fast positron interacts with motionless electron producing one photon

1. I know that if that electron were in atom, photon of some energy could give its energy, and electron would jump into a higher energy state. But what about free electron, as in this case? And why not if it's not possible?

2. positron and electron should anihilate producing photon, but I'm not sure is it 1 or two photons, and I don't know the argument why.

If you calculate the momenta and energy using Conservation laws, you should be able to see whether they are possible or not.

1. Are p and E conserved?
2. Calculate E^2-p^2 for the initial and final state.

clem said:
1. Are p and E conserved?
p=(E(photon)+E(electron), p1+p2=0) before, after I should have E of electron that exceeds rest mass of electron, and no momentum, so the answer should be that process is not possible.

clem said:
2. Calculate E^2-p^2 for the initial and final state.
It should not be possible because photon should have some momentum (three component momentum) and since it doesn't have any mass, it can't be possible.

Are these correct explanations?

Ene Dene said:
p=(E(photon)+E(electron), p1+p2=0) before, after I should have E of electron that exceeds rest mass of electron, and no momentum, so the answer should be that process is not possible.

It should not be possible because photon should have some momentum (three component momentum) and since it doesn't have any mass, it can't be possible.

Are these correct explanations?
Neither is possible, but your reasoning is flawed.
For #1, look at the barycentric (or "center of mass") system where the total momentum is zero. The final state would have total energy mc^2, while the initial system would have a higher total energy.
For #2, one photon cannot be produced because there is no center of mass system for a single photon.

## 1. What is the scientific method and how does it relate to understanding possible processes?

The scientific method is a systematic approach to understanding and explaining natural phenomena. It involves making observations, forming a hypothesis, designing experiments to test the hypothesis, and analyzing the results. Understanding possible processes involves applying the scientific method to determine which processes are feasible and why.

## 2. How do scientists determine which processes are possible?

Scientists use a combination of observations, experiments, and mathematical models to determine which processes are possible. They also consider factors such as the laws of physics, chemistry, and biology to determine the feasibility of a process.

## 3. Are there limitations to what processes are possible?

Yes, there are limitations to what processes are possible. These limitations can include physical constraints, such as the laws of thermodynamics, or technological limitations. Additionally, some processes may be possible in theory, but not currently feasible due to lack of resources or understanding.

## 4. How do scientists determine the likelihood of a process occurring?

Scientists use statistical analysis and probability calculations to determine the likelihood of a process occurring. They also consider the available evidence and past observations to make informed predictions about the likelihood of a process happening in a given situation.

## 5. Can new processes be discovered or created?

Yes, new processes can be discovered or created through scientific research and experimentation. Scientists are constantly pushing the boundaries of knowledge and discovering new processes that were previously unknown or thought to be impossible. Additionally, advancements in technology and understanding can lead to the creation of new processes that were not possible before.

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