RECENT ARTICLES

A devilish new framework of thermodynamics that focuses on how we observe information could help illuminate our understanding of probability and rewrite quantum theory.

An unusual approach to unifying the laws of physics could solve Hawking's black-hole information paradox—and its predicted gravitational "memory effect" could be picked up by LIGO.

Objective reality, and the laws of physics themselves, emerge from our observations, according to a new framework that turns what we think of as fundamental on its head.

The impossibility of building a perfect clock could help explain away microscale weirdness.

An all-encompassing framework of physics could help to explain the evolution of consciousness, intelligence, and free will.

FQXI ARTICLE

March 22, 2019

The Black Hole Universe

Is our universe housed in a black hole? Or did it exist before the Big Bang? If so, we could solve the mystery of dark energy—surprisingly, it’s all down to the humble neutrino.

FQXi Awardees: Stephon Alexander

May 28, 2010

STEPHON ALEXANDER

Haverford College

Let’s start with a little bit more about your assumed identity as a neutrino. Your mother was a proton who met up with three other protons deep inside a star. There was some nuclear fusion, she transformed herself into a neutron, and you popped out. You didn’t stick around very long, though. You have no charge and almost no mass, so you barely interact with the other particles, zipping through space, stars, and planets almost as if they aren’t even there.

So far, that’s the standard life story of a neutrino. But Stephon Alexander, a physicist at Haverford College, Pennsylvania, is shaking up that formulaic plot. What if, he ponders, time and our universe existed before the Big Bang? What if this prior version of the cosmos contracted down to a finite size, bounced, and started to expand outwards again? In that case, neutrinos, usually dismissed as being a ghostly particles with little tangible influence, could have had an extremely profound effect on the cosmos.

Subatomic Sardines

Picture yourself as a neutrino in such a contracting universe, wedged against other neutrinos like so many subatomic sardines, one hundred of you crowding every cubic centimeter of space. Under such circumstances, you and your comrades could form a new state of matter called a

Two types of physics—

neutrinos and dark energy

—appear to be built

from the same bedrock.

neutrinos and dark energy

—appear to be built

from the same bedrock.

- Stephon Alexander

A bouncing universe is only one possibility for how a neutrino condensate might form. Another is based on the notion that a collapsing star could squeeze neutrinos into a condensate, on its way to becoming a black hole. In that case, our universe might actually have formed in the neutrino soup housed inside a black hole.

A universe in a black hole may seem like an outlandish idea, but if correct, we still live within a neutrino condensate, which could be causing the expansion of the universe to accelerate. Astronomers have observed such an acceleration, and usually attribute it to some mysterious “dark energy.”

A strange parallel between neutrinos and dark energy gives Alexander a hint that he’s on the right trail. Neutrinos come in three

NEUTRINOS—DARK ENERGY’S

SECRET INGREDIENT?

The Sudbury Neutrino Observatory

(pictured) found that neutrinos

oscillate between three flavors.

Credit: NASA

Philip Phillips at the University of Illinois at Urbana-Champaign, an expert on what happens when exotic materials are squeezed down into new states of matter, finds the idea "truly novel." "Alexander has combined ideas from my field of condensed matter and put them to use in his own," he says.

While condensed matter physicists have produced examples of superfluids and condensates of other types of exotic matter, Alexander’s neutrino condensate cannot be cooked up in the lab because neutrinos are too slippery to capture and bundle together. But Alexander hopes to make testable predictions based on his theory that link the characteristics of neutrinos to the observed properties of dark energy. "We can use the universe as a laboratory to test particle physics," he says.

Lee Smolin, a theoretical physicist at the Perimeter Institute in Ontario, is a fan of Alexander’s original thinking. "He has a very fertile creativity combined with an independence of mind," he says.

So will neutrino condensation turn out to be the right answer to these cosmic riddles? Perhaps. As Smolin puts it, "We don’t know if it is true, but it is something that, so far as we know, might be true."

Comment on this Article

Please read the important Introduction that governs your participation in this community. Inappropriate language will not be tolerated and posts containing such language will be deleted. Otherwise, this is a free speech Forum and all are welcome!

function ValidatePostText_main () {
form = document.addPostForm_main;
var recaptcha = $("#g-recaptcha-response").val();
if (recaptcha === "") {
event.preventDefault();
alert("The reCaptcha Box below must be checked before you submit the form");
}
else if (form.postText_main.value == '') {
alert ("The post contains no text");
return false;
}
else {
return true;
}
}

**Your name:**
(optional)

Recent Comments

read all article comments

Please read the important Introduction that governs your participation in this community. Inappropriate language will not be tolerated and posts containing such language will be deleted. Otherwise, this is a free speech Forum and all are welcome!

Please enter the text of your post, then click the "Submit New Post" button below. You may also optionally add file attachments below before submitting your edits.

HTML tags are not permitted in posts, and will automatically be stripped out. Links to other web sites are permitted. For instructions on how to add links, please read the link help page.

You may use superscript (10

^{100}) and subscript (A_{2}) using [sup]...[/sup] and [sub]...[/sub] tags.You may use bold (

**important**) and italics (*emphasize*) using [b]...[/b] and [i]...[/i] tags.You may also include LateX equations into your post.

Insert LaTeX Equation
[hide]

LaTeX equations may be displayed in FQXi Forum posts by including them within [equation]...[/equation] tags. You may type your equation directly into your post, or use the LaTeX Equation Preview feature below to see how your equation will render (this is recommended).

For more help on LaTeX, please see the LaTeX Project Home Page.

LaTeX Equation Preview

preview equation

clear equation

insert equation into post at cursor

LaTeX equations may be displayed in FQXi Forum posts by including them within [equation]...[/equation] tags. You may type your equation directly into your post, or use the LaTeX Equation Preview feature below to see how your equation will render (this is recommended).

For more help on LaTeX, please see the LaTeX Project Home Page.

LaTeX Equation Preview

preview equation

clear equation

insert equation into post at cursor

Attachments
[hide]

You may optionally attach up to two documents to your post. To add an attachment, use the following feature to browse your computer and select the file to attach. The maximum file size for attachments is 1MB.

Once you're done adding file attachments, click the "Submit New Post" button to add your post.

You may optionally attach up to two documents to your post. To add an attachment, use the following feature to browse your computer and select the file to attach. The maximum file size for attachments is 1MB.

Once you're done adding file attachments, click the "Submit New Post" button to add your post.

BILLIONSNBILLIONS wrote on October 8, 2017

A black hole, according to Juan Maldacena, can be described by the 2-D event horizon surrounding it, every bit of information, spin, charge, etc, is mapped onto the horizon with one bit corresponding to one planck area of the event horizon. What this means is as a black hole consumes matter or energy, that information is added to the area of the event horizon, and because the event horizon is 2-d, and because the interior of a black hole is volume, as the size of a black hole grows, the density...

A black hole, according to Juan Maldacena, can be described by the 2-D event horizon surrounding it, every bit of information, spin, charge, etc, is mapped onto the horizon with one bit corresponding to one planck area of the event horizon. What this means is as a black hole consumes matter or energy, that information is added to the area of the event horizon, and because the event horizon is 2-d, and because the interior of a black hole is volume, as the size of a black hole grows, the density...

DURGADAS DATTA. wrote on June 27, 2016

The balloon inside balloon theory of matter and antimatter universes on opposite entropy path published in year 2003 has actually predicted that the outer antimatter universe is turning into a black hole gradually due to opposite entropy path. As such our universe is inside a black hole which is turning into a black hole. See the attached paper.

The balloon inside balloon theory of matter and antimatter universes on opposite entropy path published in year 2003 has actually predicted that the outer antimatter universe is turning into a black hole gradually due to opposite entropy path. As such our universe is inside a black hole which is turning into a black hole. See the attached paper.

BASIL ALTAIE wrote on April 21, 2011

As for the Black Hole Universe it might be useful to see the following article

[record/827653]

As for the Black Hole Universe it might be useful to see the following article

[record/827653]

read all article comments