Understanding Critical Energy and Thresholds in High Energy Physics

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In summary, the distinction between high energies and low energies does not have a clear threshold and is not based solely on velocity. It is a convention and there can be overlap between research fields such as High Energy Physics and Condensed Matter Physics. The categorization of energies is not the most important aspect of science and should not be a focus.
  • #1
MathematicalPhysicist
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I believe that once I asked for what is the critical speed that above it it's considered ultra-relativistic speed and below it slow speeds.
I forgot to ask about the critical energy, what is the threshold energy that below it it's considered low energy physics and above it it's considered HEP, is there such an energy? in that case how to compute it?

I would assume one needs to use the equation ##E^2=p^2+m^2##, but which momentum and mass to insert?

Is this distinction between high energies and low energies really have a threshold?
 
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  • #2
MathematicalPhysicist said:
Is this distinction between high energies and low energies really have a threshold?
No. The reason is that detecting the effects of SR would depend more on the actual experiment that the velocity involved. Take a high quality Frequency Standard with you on a trip round the Earth in a fast jet and you will detect a relativistic shift. Check the pilot's watch against the watch of his brother, who remains at the airport, and you will see no (measurable) relativistic shift.
Any "threshold" energy would be totally arbitrary. But why would that matter at all?
 
  • #3
sophiecentaur said:
No. The reason is that detecting the effects of SR would depend more on the actual experiment that the velocity involved. Take a high quality Frequency Standard with you on a trip round the Earth in a fast jet and you will detect a relativistic shift. Check the pilot's watch against the watch of his brother, who remains at the airport, and you will see no (measurable) relativistic shift.
Any "threshold" energy would be totally arbitrary. But why would that matter at all?
Then why is there such a distinction between HEP and Condensed Matter Physics?
I mean HEP= High Energy Physics so there's also low energy physics I guess, so where's the critical energy at?
 
  • #4
MathematicalPhysicist said:
Then why is there such a distinction between HEP and Condensed Matter Physics?
Is there "such a distinction"? How slow is the slowest 'fast car' on the road and how low is the lowest mountain that gets climbed?
Research departments have names which give a clue about what is studied but the names are not exclusive. Knowledge about condensed matter is needed in a High Energy Physics lab and you can bet that there will be a high energy specialist working somewhere in a Condensed Matter Physics if measurements involve high energy radiation.
I'd advise not wasting time on categorising. It's the least interesting part of Science, imo.
 
  • #5
Where do you draw the line between the largest pond and the smallest lake?
 
  • #6
This is heading in the direction of Zen, I think.:wink:
 
  • #7
But what is the dividing line between Zen and other forms of Buddhism?

More helpfully for the OP, you can usally approximate relativistic formulae and recover Newtonian ones (e.g. relativistic K.E. is ##(\gamma-1)mc^2=mv^2/2+O(v^4/c^2)##). If the neglected parts are significant to whatever precision you are measuring, you shouldn't neglect them and should consider a full-fledged relativistic treatment.
 
  • #8
Vanadium 50 said:
Where do you draw the line between the largest pond and the smallest lake?
If you are an estate agent (realtor?) there can be a large overlap. The seller's lake could be a buyer's pond.
 
  • #9
Vanadium 50 said:
Where do you draw the line between the largest pond and the smallest lake?
So there's no difference between high and low energies? it's just a convention.
A condensed matter physicist can work in HEP and vice versa, since there's no difference.
I mean we have particles in both of them... :-)
 
  • #10
There is the old-fashioned term "elastic scattering" which meant not enough energy to break anything.
 
  • #11
MathematicalPhysicist said:
So there's no difference between high and low energies?

So there's no difference between ponds and lakes?
 
  • #12
MathematicalPhysicist said:
So there's no difference between high and low energies? it's just a convention.
A condensed matter physicist can work in HEP and vice versa, since there's no difference.
I mean we have particles in both of them... :-)
I'm really not sure what you want out of this thread. You are treating Physics a bit like Top Trumps.
 
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1. What is critical energy in high energy physics?

Critical energy is the minimum amount of energy required for a particle to undergo a particular process or reaction in high energy physics. It is a threshold energy that must be reached in order to observe certain phenomena or interactions.

2. How is critical energy determined in high energy physics experiments?

Critical energy is typically determined through mathematical calculations and theoretical models based on the properties of the particles involved in the process. It can also be measured experimentally by analyzing the energy levels of particles before and after a reaction or interaction.

3. What is the significance of critical energy in high energy physics?

Critical energy is important because it allows us to understand and study the fundamental particles and forces that make up the universe. It also helps us to determine the limits and boundaries of our current understanding of physics and can lead to new discoveries and advancements in the field.

4. How does critical energy relate to the concept of thresholds in high energy physics?

Thresholds in high energy physics refer to the minimum energy required for a specific reaction or process to occur. In many cases, this threshold energy is equivalent to the critical energy. However, there may be cases where the threshold energy is higher than the critical energy, indicating that the process is more complex and requires additional energy to occur.

5. Can critical energy change in different environments or conditions?

Yes, critical energy can vary depending on the environment or conditions in which the particles are interacting. For example, in extreme conditions such as high temperatures or pressures, the critical energy may be different than in normal conditions. Additionally, the presence of other particles or forces can also affect the critical energy of a reaction or process.

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