Gravity, which baffled scientists, why is it weak and cannot be measured accurately?

Gravity is one of the four fundamental forces in the universe, along with electromagnetism and the strong and weak nuclear forces.

Despite being important enough to prevent our feet from flying off the ground, gravity remains largely a mystery to scientists.

Scientists tried in the past to provide their explanations for the fall of things to the earth. The Greek philosopher Aristotle interpreted them as having a natural tendency to move towards the center of the universe, which was believed at the time to be the middle of the earth.

Later the scientist Nicola Copernicus realized that the orbits of the planets in the sky would make more sense if the sun was the center of the solar system, and thus the Earth was excluded as the center of the universe.

Then Isaac Newton, the mathematician and physicist, extended Copernicus' insights and concluded that when the sun pulls on the planets, all bodies exert a force of attraction on one another.

In his famous thesis in 1687, Newton described what is now known as the law of universal gravitation, as stating that the forces of attraction between two physical bodies are directly proportional to the product of their masses, and inversely proportional to the square of the distance between their centers.

It is usually written as (F=G×(M1M2)/r2).

where F is the gravitational force, m1 and m2 are the masses of the two bodies, and r is the distance between them.

And G is the gravitational constant, a fundamental constant whose value must be discovered through experiment.

Is gravity as strong as we think?

Gravity is the weakest of the four fundamental forces, with evidence that a single magnetic bar is able to lift a metal paper clip up electromagnetically, overcoming the entire force of gravity, according to physicists, gravity is weaker than electromagnetism by 10^40 (this is the number 1 followed by 40 zeros) .

But why, among the fundamental forces, is gravity the weakest?

Explaining this is a profound challenge to physicists, and a major milestone on the path to a unified theory of all forces, as unifying the four fundamental forces into one theory is a long-standing scientific dream.

Scientists believe that while the effects of gravity can be clearly seen on the scale of things like planets, stars and galaxies, the force of gravity on everyday objects is extremely difficult to measure.

According to the scientific journal PNAS, in 1798, British physicist Henry Cavendish conducted one of the world's first high-resolution experiments to attempt to accurately determine the value of G, the gravitational constant.

Cavendish built what is known as a torsion balance, attaching two small balls of lead to the ends of a crossbar suspended horizontally with a thin wire.

Near each of the small balls, put a large ball weight of lead.

The small lead balls were gravitationally attracted to the heavier lead weights, causing the wire to twist only slightly, allowing him to calculate the value of G.

Remarkably, Cavendish's estimate of G's value differed only by 1% from its modern-day accepted value, which is 6.674 x 10^−11 m^3/ kg^1 * s^2, according to Live Science.

Most other cosmological constants are known to have much higher accuracy, but due to weak gravity, scientists must design highly sensitive equipment to try to measure their effects;

But - so far - the more accurate G value has eluded their tools.

A collision between two black holes approaching each other to form a giant vortex and releasing gravitational waves (Wikipedia)

Einstein revolutionized the understanding of gravity

The next revolution in our understanding of gravity was Albert Einstein, whose theory of general relativity showed that gravity arises from the curvature of space-time, meaning that even light rays, which must follow this curvature, are bent by extremely massive objects.

Einstein's theories were used to speculate about the existence of black holes, which are entities with so much mass that not even light can escape from their surfaces.

So, near a black hole, Newton's law of universal gravitation no longer accurately describes how objects move, but Einstein's equations take precedence.

Astronomers have since discovered real black holes in space, and have even been able to capture a detailed picture of the supermassive black hole at the center of our galaxy.

Other telescopes have seen the effects of black holes throughout the universe.

The application of Newton's law of gravitation to very light objects, such as humans, cells, and atoms, remains a kind of unexamined frontier;

The researchers hypothesize that such entities should attract each other using the same gravitational rules as planets and stars, but due to the weak gravitational pull, it's hard to know for sure.

Perhaps if scientists can accurately measure the forces of gravity, it will be possible to understand the hidden aspects of the universe.

While light carries a particle called a photon, physicists have no idea if there is a particle equivalent to gravity (Urik Alert)

An enduring force of mystery

Gravity baffles scientists in other ways as well. Standard modeling theory of particle physics, which describes the behavior of nearly all known particles and forces, ignores gravity.

While light carries a particle called a photon, physicists have no idea if there is an equivalent particle of gravity, which could be called a graviton.

Combining gravity in a theoretical framework with quantum mechanics remains an unfinished task.

Although the other three fundamental forces are consistent with quantum mechanics (the science of very small things), gravity is very different with it.

The equations of quantum mechanics collapse, if gravity is added to them, and how to reconcile these two accurate descriptions of the universe is one of the biggest physics problems today.

On the other hand, gravity is still used to make the most important discoveries.

In the 1960s and 1970s, astronomers Vera Rubin and Kent Ford showed that stars at the edges of galaxies were spinning faster than they should be, as if an invisible mass was gravitational pull on them, shining a light on a substance scientists now call "dark matter." ".

In recent years, scientists have also been able to capture another result of Einstein's relativity, which is the gravitational waves emitted by the rotation of massive objects such as neutron stars and black holes around each other.

Since 2017, the Laser Interferometer Gravitational-Wave Observatory (LIGO) has opened a new window into the universe by detecting the very faint signal of such events.

Scientists are trying to look for gravitational waves to understand them more.