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  • I think it's safe to say that Einstein was a pretty smart guy.

  • His theory of general relativity states that matter and energy, then the very fabric of space time and that revelation gave us such a useful description of how gravity works.

  • That has been the go to for astronomers for more than a century.

  • Still as good as it is, general relativity isn't perfect.

  • And there are situations where Einstein's equations break down, like at the center of a black hole or the singularity before the Big Bang.

  • However, a new paper suggests the key to filling in those gaps may be discovered by searching for, and this is a highly technical term here.

  • The quantum fuzziness of space time Gravity is somewhat of the odd one out when it comes to the four fundamental forces of nature, according to Einstein.

  • It works by curving space time affecting how objects like planets and apples travel through it.

  • The other three forces, the electromagnetic force and the strong and weak nuclear forces can be described using the standard model of particle physics.

  • These three forces are carried by subatomic particles called bosons.

  • The strong force is carried by the gluon electromagnetism is carried by a Boesen.

  • You've probably heard of the photon, and the weak force is carried by the W and Z bosons.

  • We've seen these bosons experimentally, but we've never observed a particle that carries the force of gravity.

  • And that's irksome because a hypothetical Boesen called a graviton could solve some major issues in physics.

  • Firstly, it would fit neatly into the pattern the other three forces have set to have gravity off, doing its own thing and playing by its own rules.

  • It just doesn't sit right, at least not with a lot of theorists.

  • More importantly, it could finally bridge the divide between general relativity and quantum mechanics.

  • Right now, General relativity is great and describing how gravity works at scales ranging from submillimeter to cosmological.

  • But it doesn't work at quantum levels.

  • A full theory of quantum gravity could finally expand Einstein's ideas to fill in these gaps in our understanding.

  • But gravitons, if they exist, would be difficult to detect by their nature.

  • Despite another force literally being called the weak force, gravity is by far the weakest of the quartet.

  • The renowned physicist Freeman Dyson suggested that a hypothetical detector sensitive enough to observe a single graviton would be so massive that the detector itself would collapse into a black hole.

  • But what if we're going about this the wrong way?

  • What if?

  • Instead of trying to find just one graviton, we search for a telltale sign that only a group of them can create.

  • That's what three researchers proposed in a paper from October of 2020.

  • The physicists were inspired by Brownie in Motion, which describes how particles in a fluid bounce around randomly.

  • If gravity really is carried by bosons, then maybe they move around randomly to creating a sort of noise or fuzziness that existing gravitational wave detectors like LIGO can suss out.

  • Of course, the noise has to be pronounced enough for Lego to notice.

  • It's a bit beyond the scope of this episode, but just know that waves like light can come in different quantum states.

  • In fact, LIGO uses light in a squeezed state to enhance sensitivity, the researchers calculated that gravitational waves in different quantum states would produce different amounts of noise.

  • Waves in a coherent state are like ripples in a pond there produced during black hole mergers, and LIGO is tuned to search for them.

  • Unfortunately, in this state, gravitas would hardly make any noise.

  • However, according to the researchers calculations, gravitational waves in the so called squeezed state should produce much more noise, and that noise should increase exponentially the more the gravitas are squeezed.

  • So let's just start looking for some squeezed gravitational waves, right?

  • Uh, not so fast.

  • It's not clear if they even exist.

  • The researchers suggest that they could be squeezed into existence during the late stages of black hole mergers or during an early period in the universe.

  • If that's true, or if there's some other source of squeezed gravitational waves out there.

  • And if we can make instruments sensitive enough to hear the noise of gravitons, then maybe we can finally find a way to bring quantum mechanics and general relativity together.

  • If you want to know more about gravitational wave detectors like Lego, check out my video on these awesome machines here and make sure to subscribe a secret for more videos like this one.

I think it's safe to say that Einstein was a pretty smart guy.

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B2 quantum gravity squeezed general relativity gravitational relativity

How Scientists Are Using Fuzziness To Solve the Mystery of Quantum Gravity

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    林宜悉 posted on 2021/03/17
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