Question: What serves as a tool to gauge the properties of large scale structures?
About the article "Astrophysics", section "Theoretical astrophysics".

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Topics studied by theoretical astronomers include:  stellar dynamics and evolution;  galaxy formation;  large-scale structure of matter in the Universe;  origin of cosmic rays;  general relativity and physical cosmology, including string cosmology and astroparticle physics.
Astrophysical relativity serves as a tool to gauge the properties of large scale structures for which gravitation plays a significant role in physical phenomena investigated and as the basis for black hole ("astro")physics and the study of gravitational waves. 
Theoretical astronomers use several tools including analytical models (for example, polytropes to approximate the behaviors of a star) and computational numerical simulations.
Each has some advantages.
Analytical models of a process are generally better for giving insight into the heart of what is going on.
Numerical models reveal the existence of phenomena and effects otherwise unobserved.
Theorists in astronomy endeavor to create theoretical models and from the results predict observational consequences of those models.
The observation of a phenomena predicted by a model allows astronomers to select between several alternate or conflicting models.
Theorists also try to generate or modify models to take into account new data.
In the case of an inconsistency, the general tendency is to try to make minimal modifications to the model so that it produces results that fit the data.
In some cases, a large amount of inconsistent data over time may lead to total abandonment of a model.
Topics studied by theoretical astronomers include: stellar dynamics and evolution; galaxy formation; large-scale structure of matter in the Universe; origin of cosmic rays; general relativity and physical cosmology, including string cosmology and astroparticle physics.
Astrophysical relativity serves as a tool to gauge the properties of large scale structures for which gravitation plays a significant role in physical phenomena investigated and as the basis for black hole ("astro")physics and the study of gravitational waves.
Some widely accepted and studied theories and models in astronomy, now included in the Lambda-CDM model are the Big Bang, Cosmic inflation, dark matter, and fundamental theories of physics.
A few examples of this process:Dark matter and dark energy are the current leading topics in astronomy, as their discovery and controversy originated during the study of the galaxies. 
Theoretical astrophysicists use a wide variety of tools which include analytical models (for example, polytropes to approximate the behaviors of a star) and computational numerical simulations.
Each has some advantages.
Analytical models of a process are generally better for giving insight into the heart of what is going on.
Numerical models can reveal the existence of phenomena and effects that would otherwise not be seen.
Theorists in astrophysics endeavor to create theoretical models and figure out the observational consequences of those models.
This helps allow observers to look for data that can refute a model or help in choosing between several alternate or conflicting models.
Theorists also try to generate or modify models to take into account new data.
In the case of an inconsistency, the general tendency is to try to make minimal modifications to the model to fit the data.
In some cases, a large amount of inconsistent data over time may lead to total abandonment of a model.
Topics studied by theoretical astrophysicists include: stellar dynamics and evolution; galaxy formation and evolution; magnetohydrodynamics; large-scale structure of matter in the universe; origin of cosmic rays; general relativity and physical cosmology, including string cosmology and astroparticle physics.
Astrophysical relativity serves as a tool to gauge the properties of large scale structures for which gravitation plays a significant role in physical phenomena investigated and as the basis for black hole ("astro")physics and the study of gravitational waves.
Some widely accepted and studied theories and models in astrophysics, now included in the Lambda-CDM model are the Big Bang, Cosmic inflation, dark matter, dark energy and fundamental theories of physics.
Wormholes are examples of hypotheses which are yet to be proven (or disproven).
Net Promoter is a management tool that can be used to gauge the loyalty of a firm's customer relationships.
It serves as an alternative to traditional customer satisfaction research and claims to be correlated with revenue growth. 
As a consequence, of the track gauges, plus overscale track, finescale standards have been developed.
These include EM gauge (4mm scale, 18.2mm gauge), P4 gauge (4mm scale, 18.83mm gauge), 3mm finescale (3mm scale, 14.2mm gauge), 2mm finescale (2mm scale, 9.47mm gauge).
Others have adopted H0 gauge.