Name: What Is Gravity Made Of?
Uploaded: undefined
Duration: undefined

Nova

Koch Foundation

NOVA Science Trust Logo

<div class="rich-text"><p>One of the most incredible physics discoveries of the century has revealed a "cosmic fingerprint" explaining the beginning of universe and gravity's microscopic secrets. Go back to the beginning of time to see how quantum particles in the infant universe gave rise to a phenomenon called "inflation." This new evidence tells not only why the universe exploded outward during its birth, but also that gravity is made of quantum particles, called gravitons.</p>
</div>

A "cosmic fingerprint" reveals the universe's beginning and gravity's microscopic secrets.

A "cosmic fingerprint" reveals the universe’s beginning and gravity's microscopic secrets.

What Is Gravity Made Of?

<div class="rich-text">A "cosmic fingerprint" reveals the universe's beginning and gravity's microscopic secrets.</div>

Physics & Math

<div class="rich-text"><h3>
 What Is Gravity Made Of?
</h3>
<p>
 May 8, 2014
</p>
<p>
 One of the most incredible and surprising physics discovery of this century was just made by a team of scientists based at the South Pole, operating a telescope, called BICEP2.
</p>
<p>
 They found a celestial fingerprint that not only explains the explosive beginning of time, but also reveals gravity's microscopic secrets. To understand what this fingerprint is, imagine turning back the cosmic clock to just after the big bang, when the universe was crowded into a hot, dense ball over a billion times smaller than an atom's nucleus.
</p>
<p>
 For decades, physicists have wondered what laws of nature would dominate here; the tiny size of the universe meant the seething, ethereal world of quantum particles should be at play, but the immense mass meant the space-bending world of gravity should also be at work.
</p>
<p>
 So the physicist merged these worlds, and came up with a strange idea. They proposed that gravity is actually made of quantum particles, which they called "gravitons." Anywhere there is gravity, there would be gravitons: on earth, in solar systems, and most importantly in the miniscule infant universe where quantum fluctuations of gravitons sprung up, bending pockets of this tiny space-time. But if gravitons are everywhere, why can't we see them?
</p>
<p>
 Unfortunately, a single graviton is too measly to detect, so we had no evidence of them. But scientists made another assumption about the moment after the big bang. They proposed that in this tiny cramped ball, instead of gravitational attraction between matter, there would have been a fierce gravitational repulsion, which would have caused everything to explode outward in a momentary event called "inflation." During inflation, the once tiny graviton fluctuations also inflated into large gravitational waves.
</p>
<p>
 In the following, infant, years of the universe, photon particles of light and charged particles were so crowded in space that they were constantly colliding, meanwhile the gravitational waves stretched and contracted parts of space, causing cold spots and hot spots to form.
</p>
<p>
 Where these spots met, photons ricocheting off charge particles became aligned and together all these photons produced distinct patterns in the cosmic glow. Around 380,000 years after the big bang, the universe becaÂ­me so large and all the particles were so spread out that the collisions stopped, and the final patterns of light streamed out through space, where we can see them today.
</p>
<p>
 The swirls in these twisting patterns of light are called "b-modes", and they are the fingerprint that the scientists found. They're the first direct evidence for the inflation or explosion that birthed our universe and the strongest evidence we've ever had that gravity is, in fact, made of tiny particles, called gravitons.
</p></div>

United States

Northern Mariana Islands

Puerto Rico

American Samoa

Guam

U.S. Virgin Islands

U.S. Minor Outlying Islands

US & Territories

<p>NOVA investigates the story of cannabis from the criminalization that has disproportionately harmed communities of color to the latest medical understanding of the plant. What risks does cannabis pose to the developing brain? How much do we know about its potential medical benefits? As cannabis becomes socially accepted, scientists are exploring its long-term health consequences. (Premiered September 29, 2021)</p><p>Check out a previously recorded panel discussion and audience Q&amp;A featuring experts and producers from "The Cannabis Question" <a href="https://youtu.be/nSTT5RZ_hxA">here</a>.</p>

<p>As state-legalized cannabis spreads, NOVA explores its little-known risks and benefits.</p>

The Cannabis Question

A 2006 composite image from NASA's Hubble Space Telescope and Spitzer Telescope shows the chaos of baby stars in the Orion nebula some 1,500 light-years away. Image Credit: NASA/JPL-Caltech/STScI

<p>With the upcoming launch of the James Webb Space Telescope, the Hubble era is gradually drawing to a close. Here are some highlights from the countless wonders Hubble has shown us during its 31 years in space.</p>

10 spectacular Hubble Space Telescope images

A statue of Zheng He at the Sam Poo Kong Temple in Java, Indonesia. Image Credit: Budianto Santosa, Shutterstock

<p>In the 1400s, Zheng He sailed thousands of miles around Asia and Africa in ships the size of soccer fields, spreading Chinese innovations like compasses and gunpowder in the process. </p>

Transcript

Credits

Support Provided By