Final answer:
Volume in nuclear physics is context-dependent and varies when measuring dense plasma in the Sun's core versus a stable substance like lead on Earth.
Astrophysicists use solar models and sophisticated observations like helioseismology to estimate properties of the Sun's core, which is a high-pressure, high-temperature environment allowing nuclear fusion to occur.
Step-by-step explanation:
The concept of volume, space, and distance in nuclear physics, especially when discussing the Sun's core versus something like a piece of lead on Earth, encompasses different scales and requires different measurement techniques.
On the quantum level, the volume of a nucleus can be described considering the dense packing of protons and neutrons within it. In the context of the Sun's core, the measurement of volume involves estimating the space occupied by the extremely dense and hot plasma where nuclear fusion occurs.
At the scale of the Sun's core, which comprises about 20% of the solar interior, volume isn't defined or measured at the sub-millimetre level because standard measurement tools used on Earth are impractical in such extreme conditions.
Instead, astrophysicists use solar models to describe the structure of the Sun's interior and use observations such as helioseismology to estimate pressure, temperature, mass, and luminosity relative to distance from the Sun's center.
These scientific models and observations help describe the Sun's core as a densely packed, high-pressure environment where nuclear fusion of hydrogen into helium occurs at temperatures of approximately 15 million Kelvin.
This differs significantly from measuring volume in a piece of lead on Earth, where atomic scales are stable and measurable using conventional physics and laboratory instruments.