Beijing time, June 29, according tomedia reports, there are many physical theories predict that there are many dimensions in the universe in addition to the four dimensions we know (three spatial dimensions and one time dimension). With these extra dimensions, some of the universe’s most complex mysteries are easy to explain. For example, some theories that explain dark matter and dark energy are premised on the existence of multiple “extra” dimensions in the universe, which are around us, but too small to observe.
And in 2017, the universe offers us a great opportunity to validate. More than 130 million light-years away, two neutron stars merge after colliding, creating gravitational waves that sweep across the universe like a tsunami. The gravitational wave was detected by the Laser Interference Gravitational Wave Observatory (LIGO) of the United States and the Virgo Observatory in Italy on August 17, 2017. In addition, the event also formed a thousand new stars, produced an extremely bright gamma ray storm, and left behind a gold and other heavy elements. The gravitational wave detectors in the United States and Italy recorded the formation of the space-time ripples, while NASA’s Neil Grylls Swift Observatory and others detected electromagnetic radiation.
The incident excited astrophysicists. For the first time in history, they observed electromagnetic and gravitational waves from the same event, and were able to compare two signals to make new discoveries related to the universe. The discovery not only won the Nobel Prize in Physics for scientists, but also ushered in a new era of “multi-messenger astronomy”.
Since then, researchers have used this historic event to further explore dimension levels beyond the four known spatial and temporal dimensions. It turns out that our universe may be much simpler than many physical theories predict.
Again, we mentioned the mystery of dark matter and dark energy. Scientists believe that most of the matter in the universe is made up of matter that we cannot see. We don’t know what these substances are, but we can feel their gravitational effects, so we know they’re there. And the dark energy is even more elusive. Like dark matter, dark energy has a “dark” word in its name, because we really don’t know what it is. But we also know that it must exist, and cosmologists believe that dark energy is the driving driver behind the accelerated expansion of the universe.
Scientists have come up with many theories about dark matter and dark energy, some of which require additional dimensions to be established. Interestingly, in exploring these unknown extra dimension areas, we may be able to exploit gravitational waves.
In short, scientists believe that if there were other dimensions, when gravitational waves travel at the speed of light in the air, some of the energy of gravitational waves “leaks” into these extra dimensions. Therefore, when monitored by the Gravitational Wave Observatory, the amplitude of the gravitational wave should be less than expected. General electromagnetic radiation, such as gamma-ray bursts of light, does not interact with these additional dimensions and therefore does not change. In theory, if there are other dimensions, there is a deviation between the gravitational wave signals detected in 2017 and the electromagnetic signals.
However, studies have shown that there is no difference between the two signals, suggesting that the propagation of both light signals and gravitational waves is limited to four-dimensional space-time. This is also in line with Einstein’s general theory of relativity. Not only that, but the theory predicted the existence of gravitational waves more than a century ago.
This does not mean that the extra dimensions must not exist, or that our theory of gravity needs to be modified, or that we need to measure more multi-messenger events. But this at least suggests that the discovery of gravitational waves has been fulfilling its “promises” just a few years after it has passed the region, and has really challenged some of the key cosmic theories.