Search FQXi

If you are aware of an interesting new academic paper (that has been published in a peer-reviewed journal or has appeared on the arXiv), a conference talk (at an official professional scientific meeting), an external blog post (by a professional scientist) or a news item (in the mainstream news media), which you think might make an interesting topic for an FQXi blog post, then please contact us at with a link to the original source and a sentence about why you think that the work is worthy of discussion. Please note that we receive many such suggestions and while we endeavour to respond to them, we may not be able to reply to all suggestions.

Please also note that we do not accept unsolicited posts and we cannot review, or open new threads for, unsolicited articles or papers. Requests to review or post such materials will not be answered. If you have your own novel physics theory or model, which you would like to post for further discussion among then FQXi community, then please add them directly to the "Alternative Models of Reality" thread, or to the "Alternative Models of Cosmology" thread. Thank you.

Forum Home
Terms of Use

Order posts by:
 chronological order
 most recent first

Posts by the blogger are highlighted in orange; posts by FQXi Members are highlighted in blue.

By using the FQXi Forum, you acknowledge reading and agree to abide by the Terms of Use

 RSS feed | RSS help

Domenico Oricchio: on 6/29/12 at 8:33am UTC, wrote I am thinking to the possibility to measure the first light, near the Big...

Lawrence B. Crowell: on 6/29/12 at 3:23am UTC, wrote The preprint can be accessed at: A robust...

Matthew Johnson: on 6/28/12 at 16:08pm UTC, wrote What types of phases could the universe have inhabited in the distant past?...


Georgina Woodward: "Hi Markus, the Guinea pigs 'paradox' raises the question; What is I? Is the..." in The Room in the Elephant:...

Georgina Woodward: "Hi Markus, ​ In regard to "what is seen next?" David Eagleman has a..." in The Room in the Elephant:...

Stefan Weckbach: "Dear Lorraine, “If you will forgive me for saying so, the situation is..." in The Present State of...

Georgina Woodward: "Perhaps the idea of consciousness causing collapse is being overthought? ..." in Consciousness and the...

Lorraine Ford: "Stefan, I would say that we individual human beings, and the rest of the..." in The Present State of...

Georgina Woodward: "Thank you John. What did you think about the questioning whether altitude..." in The Nature of Time

John Cox: "Sorry, Georgina, I have had a busy summer and am racing the change of..." in The Nature of Time

Jim Snowdon: "If the Earth did not have it`s rotational motion, the apparent time of day..." in The Quantum Clock-Maker...

click titles to read articles

Reconstructing Physics
New photon experiment gives new meta-framework, 'constructor theory,' a boost.

The Quantum Engineer: Q&A with Alexia Auffèves
Experiments seek to use quantum observations as fuel to power mini motors.

The Quantum Clock-Maker Investigating COVID-19, Causality, and the Trouble with AI
Sally Shrapnel, a quantum physicist and medical practitioner, on her experiments into cause-and-effect that could help us understand time’s arrow—and build better healthcare algorithms.

Connect the Quantum Dots for a New Kind of Fuel
'Artificial atoms' allow physicists to manipulate individual electrons—and could help to reduce energy wastage in electronic devices.

Can Choices Curve Spacetime?
Two teams are developing ways to detect quantum-gravitational effects in the lab.

September 26, 2021

CATEGORY: Blog [back]
TOPIC: Searching for Cosmic Textures [refresh]
Bookmark and Share
Login or create account to post reply or comment.

Blogger Matthew Johnson wrote on Jun. 28, 2012 @ 16:08 GMT
What types of phases could the universe have inhabited in the distant past? We know that the universe was hot and dense in its youth, and has subsequently been cooling as it expands. Just like H2O can exist as liquid water, ice, and steam, it is possible that the constituents of our universe can exist in different phases, and that transitions between these phases could have occurred in our past. In many cases, such cosmological phase transitions give rise to imperfections known as topological defects, which can survive until today, and possibly be detected through cosmological observations. Recently my colleagues Stephen Feeney, Hiranya Peiris, and Daniel Mortlock and I performed a search for a particular type of topological defect known as cosmic textures in Cosmic Microwave Background data from the WMAP satellite.

Before I describe our results, here is a little more on the background. Topological defects arise in theories where symmetries are broken as the universe cools. Symmetries abound in theories of high energy physics. For example, the standard model of particle physics can be specified by its symmetries: this determines the types and number of particles and the interactions between them. Underlying symmetries give rise to the unification of forces, and are a pillar of modern physics. To illustrate the types of symmetries I am referring to, here is a simple example: consider a theory with three interacting particles that have rotational symmetry in field space (a space where the axes are labeled by these three types of particles). Just as one can have rotational symmetry in real three dimensional space, one can have rotational symmetry in field space. There are many combinations of the three particles and their interactions that look identical. Such a symmetry of the field space is known as a global symmetry.

In the early universe, there might have been a set of such fields which possess this rotational symmetry. At each point in space, there will be a different combination of the fields, since all combinations are equivalent. However, as the universe cools, this symmetry can be broken, making the different combinations of fields no longer equivalent. Knots in the field configuration form at locations in space where the field combinations change. These knots carry energy, and are known as cosmic textures.

Until as recently as the mid-nineties, cosmic textures (along with cosmic strings) were a leading candidate for producing the seeds of galaxy formation. The predictions for cosmic textures were explored in seminal papers by Turok and Spergel. The main competing theory was

cosmic inflation, where the density fluctuations are produced by quantum fluctuations. Density fluctuations induce temperature fluctuations in the Cosmic Microwave Background radiation (CMB), and these two theories are distinguished by their predictions for the statistical properties of these fluctuations. One of the most important results of the WMAP satellite was to definitively rule out topological defects as the main seeds of structure formation; the data came down strongly in support of the inflationary hypothesis.

However, there is still the very real possibility that textures or other topological defects might be lurking in the background, making up only a small component of the density fluctuations. This idea has strong theoretical support from particle physics, because of the importance of symmetry breaking. In this scenario, the name of the game is to look for individual textures as opposed to studying the overall statistical properties of the CMB: the main component of the fluctuations now acts as a ``noise" which must be removed in order to uncover the presence of individual textures.

So, are there any features in the CMB which look like they might be described by cosmic textures? A series of important papers by Cruz et. al. suggested that the answer might be yes. The temperature fluctuations in the CMB are characterized by their statistics. Given a theory of the statistics, it is therefore possible to ask just how unlikely it is to find a feature of a particular type. There is one particularly famous feature, the CMB Cold Spot, which seems very anomalous. In addition, the shape and size of the Cold Spot is well-described by the shape and size expected of a cosmic texture.

This lead Cruz et. al. to conjecture that there is evidence for cosmic textures in the CMB. This result was predicated on a very small portion of the available CMB data: the Cold Spot occupies roughly one percent of the observed area on the CMB sky. If the cold spot was a texture, the theory of how textures are formed predicts that there should be other textures visible in different directions on the sky. This was recognized by Cruz et. al. However, an analysis that tests the predictions of the theory on the full sky is extremely challenging due both to the volume of data and to the huge number of possible arrangements of textures on the sky.

Stephen, Hiranya, Daniel, and I were able to overcome these difficulties, and devise an algorithm that can test the theory of cosmic textures using all of the available CMB data. This work built on our previous search for the signatures of cosmic bubble collisions. Our strategy was to use a two-step method where we first identify promising candidate signatures (such as the Cold Spot) and then directly compare the probability for a theory with cosmic textures to a theory without, given the data. We concluded that when you take all the data into account, the data do not warrant augmenting the standard cosmological model with cosmic textures. However, there are some interesting hints that there could be a weak signal. We'll have to wait for better data to see for sure.

Fortunately, we won't have to wait long since we will be able to perform an improved analysis on data from the Planck satellite when it becomes public in early 2013. At worst, this will yield much stronger constraints on theories that predict cosmic textures. At best, we may find evidence for textures, which can then be corroborated with data on the polarization of the CMB from Planck when it becomes available in a few years. This is a very exciting time for cosmology, as the flood of new data is allowing us to test fundamental physics in ways that were never possible before. I look forward to seeing whether textures, or something else, may be lurking in the background!

Bookmark and Share
this post has been edited by the author since its original submission

report post as inappropriate

Lawrence B. Crowell wrote on Jun. 29, 2012 @ 03:23 GMT
The preprint can be accessed at:

A robust constraint on cosmic textures from the cosmic microwave background

Authors: Stephen M. Feeney, Matthew C. Johnson, Daniel J. Mortlock, Hiranya V. Peiris

(Submitted on 8 Mar 2012 (v1), last revised 28 May 2012 (this version, v2))

Abstract: Fluctuations in the cosmic microwave background (CMB) contain information which has been pivotal in establishing the current cosmological model. These data can also be used to test well-motivated additions to this model, such as cosmic textures. Textures are a type of topological defect that can be produced during a cosmological phase transition in the early universe, and which leave characteristic hot and cold spots in the CMB. We apply Bayesian methods to carry out a rigorous test of the texture hypothesis, using full-sky data from the Wilkinson Microwave Anisotropy Probe. We conclude that current data do not warrant augmenting the standard cosmological model with textures. We rule out at 95% confidence models that predict more than 6 detectable cosmic textures on the full sky.

Bookmark and Share
report post as inappropriate

Domenico Oricchio wrote on Jun. 29, 2012 @ 08:33 GMT
I am thinking to the possibility to measure the first light, near the Big Bang.

The high red-shift of first light move the light frequency in the infrared, so that a infrared spectrum analysis in the black zone in the visible space, can identify the original spectrum emission; I think that is possible to mathematically translate the infrared spectrum to a visible, and - usual - spectrum (measuring primordial chemical processes).

I think that the high energy x-ray spectrum remain optically visible after the red-shift translation, so that I think that can be possible to see extreme source near the Big Bang (if they existed) and the high energy massive particles: a source measured in infrared, x-ray and particles can have a measured red-shift (distance).

The measure of the red-shift translation can be useful to measure the emission in different shell, so that can be possible measure the energy distribution in a three-dimensional map of the Universe (it is possible to measure differences in the chemical processes with the age of the Universe).



Bookmark and Share
report post as inappropriate

Login or create account to post reply or comment.

Please enter your e-mail address:
Note: Joining the FQXi mailing list does not give you a login account or constitute membership in the organization.