Correcting units from this physics paper?

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In summary, the paper discusses the importance of ensuring correct units in physics calculations, highlighting common mistakes and providing guidelines for unit conversion and consistency. It emphasizes the need for clarity and precision in scientific communication to avoid misunderstandings and errors in experimental and theoretical work.
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halcyon_zomboid
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I cannot make units work in this 1973 paper by Hora and need a trustworthy answer.
Hi all,

I've struggled to resolve a units issue in this 1973 paper by Hora:
https://www.academia.edu/23774741/E...tihydrogen_by_lasers_of_very_high_intensities
From the paper:

"
The number [itex]N_p[/itex] of pairs produced in a plasma volume [itex]V[/itex] during a time [itex]\tau[/itex] and a density [itex]n_e[/itex] of electrons is
[tex]N_p=\frac{e^8n_e^2}{\pi\hbar^2m_0^2c^5}V\tau\ln^3\frac{\epsilon_{kin}}{m_0c^2}.[/tex]
"

However, the units do not seem to work out as the LHS is dimensionless.

For what it's worth, I found that Equation (25) is missing one factor of [itex]E_v[/itex]:
[tex]\gamma=\frac{e^2\hbar}{\omega m_0^3c^3}E_v\quad(\mathrm{Incorrect})\quad\Rightarrow\quad\gamma=\frac{e^2\hbar}{\omega m_0^3c^3}E_v^2\quad(\mathrm{Correct})[/tex]

However, I can't tell what factors are missing in this expression. Even in units where [itex]k=1/(4\pi\epsilon_0)=1[/itex], I end up with dimensions of [itex]\mathrm{length}^{-3}[/itex] where I'm expecting dimensionless units.

FWIW, going back to Equation (28):

[tex]\sigma=\frac{e^8}{\pi\hbar^2m_0^2c^6}\ln^3\frac{\epsilon_\mathrm{kin}}{m_0c^2}[/tex]

I get dimensions of [itex]\mathrm{length}^{-2}[/itex], not [itex]\mathrm{length}^2[/itex].

It looks like this is very close to working... please, can someone help me "debug" the units here?

Thanks in advance,
HZ
 
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  • #2
To fllow you what physical dimension e has in your estimation ?
 

FAQ: Correcting units from this physics paper?

How do I identify incorrect units in a physics paper?

To identify incorrect units in a physics paper, carefully check each equation and ensure that the units on both sides are consistent. Additionally, verify that the units used match the standard units for the physical quantities involved. Cross-referencing with reliable sources or unit conversion tools can also help identify discrepancies.

What are the common mistakes when using units in physics papers?

Common mistakes include using incorrect unit conversions, mixing up units (e.g., confusing meters with centimeters), not converting units to a consistent system (e.g., SI units), and neglecting to include units in calculations or results. These errors can lead to incorrect conclusions and should be carefully checked.

How can I correct unit errors in my calculations?

To correct unit errors, first identify where the error occurred by re-evaluating each step of your calculation. Ensure that you consistently use the correct conversion factors and that units cancel out appropriately in each step. If necessary, rewrite the calculations with the correct units and verify the final result.

What resources can I use to verify the correct units for physical quantities?

Reliable resources include physics textbooks, scientific journals, and online databases such as NIST (National Institute of Standards and Technology) or the International System of Units (SI). These sources provide standardized units and conversion factors for various physical quantities.

How important is it to use consistent units throughout a physics paper?

Using consistent units throughout a physics paper is crucial for accuracy and clarity. Inconsistent units can lead to incorrect results and misinterpretations. It is essential to adopt a standard unit system, such as the SI units, and stick to it throughout the paper to ensure that calculations and conclusions are valid.

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