The size scale comparison between a quark and the entire universe is vast, spanning many orders of magnitude. While it is difficult to pinpoint an exact mid-point between the two scales, we can consider some approximate sizes to give you a sense of the relative scales involved.
The size of a quark is extremely small. Quarks are considered point-like particles in the Standard Model of particle physics, meaning they have no known internal structure or size. They are typically treated as mathematical entities without any physical extent. Quarks are believed to be on the order of 10^(-19) to 10^(-18) meters in size, which is many orders of magnitude smaller than even the smallest known subatomic particles.
On the other hand, when we talk about the size of the universe, it is important to note that the observable universe, the portion of the universe that we can potentially observe, has a finite size. The current estimate for the observable universe's radius is approximately 46.5 billion light-years. Keep in mind that the universe itself might be much larger, potentially infinite or significantly larger than the observable universe, but its exact size is still a topic of scientific investigation.
So, in terms of a mid-point, we are looking at a scale somewhere between the extremely small size of a quark (around 10^(-19) to 10^(-18) meters) and the radius of the observable universe (approximately 46.5 billion light-years). This scale would be difficult to define precisely, but it would likely fall in the range of a few billion light-years or significantly smaller.
It's important to remember that these scales are estimates and subject to ongoing research and refinement as our understanding of the universe evolves.