Featured Research

from universities, journals, and other organizations

Hubble bubble may explain different measurements of expansion rate of the universe

Date:
September 9, 2013
Source:
Heidelberg University
Summary:
The observable universe has been expanding since the Big Bang. It still is, causing galaxies beyond our Local Group to appear to be receding from us. The actual speed of this expansion is known as the Hubble constant. Due to its importance in calculating basic properties of the universe, such as its age, modern cosmology is tasked with determining the value of the constant. There are two conventional methods used, although their results are not congruent, according to researchers. Experts may now be able to explain the different measurements of the expansion of the universe.

Hubble Bubble simulation: Our home galaxy would lie in the centre of the marked empty bubble. The Hubble Bubble's very large size, however, makes the Milky Way unrecognizable. The matter at the edge of the bubble attracts our neighbouring galaxies, causing them to accelerate.
Credit: Wessel Valkenburg/Falcon

The existence of the "Hubble Bubble" may explain, at least in part, the differing measurements for the expansion and therefore the age of the universe. That is the assumption of a team of physicists headed by Prof. Dr. Luca Amendola from the Institute for Theoretical Physics at Heidelberg University. In collaboration with colleagues from the Netherlands, the Heidelberg physicists developed a theoretical model that places the Milky Way inside of this type of cosmic bubble. The researchers believe the bubble can explain some of the deviations between previous measurements and the latest ones from the Planck satellite of the European Space Agency (ESA).

The results of their research were published in the journal Physical Review Letters.

The observable universe has been expanding since the Big Bang. It still is, causing galaxies beyond our Local Group to appear to be receding from us. The actual speed of this expansion is known as the Hubble constant. Due to its importance in calculating basic properties of the universe, such as its age, modern cosmology is tasked with determining the value of the constant. There are two conventional methods used, although their results are not congruent, according to Dr. Valerio Marra from Heidelberg University's Institute for Theoretical Physics. "This has been the source of intense, long-standing debate in the scientific community."

One way to determine the Hubble constant, and hence the universe's rate of expansion, is based on measuring the cosmic microwave background radiation in space. It was released approximately 400,000 years after the Big Bang and pervades the entire universe. Several months ago the Planck satellite from the ESA delivered measurements of this ancient radiation. The Hubble constant, however, can also be derived from the movement of galaxies near the Milky Way, movement largely due to the expansion of the universe. "When you compare the results from the two methods, there is a deviation of about 9 percent," explains Dr. Marra.

In their search to explain the difference in data, the Heidelberg team thought that the reason was not some previously unrecognized error in measurement, but based on a physical effect. According to Dr. Marra, the existence of the Hubble Bubble could be the cause. The bubble describes regions of the universe where the density of matter falls below the cosmic average. "Until now knowledge of our cosmic neighbourhood has been too imprecise to determine whether or not we are in such a bubble," continues Dr. Marra. "But let's just assume for a moment that our Milky Way is located in a Hubble Bubble. Matter outside the bubble would then attract nearby galaxies so strongly that they would move more quickly than average. In this case we would measure a higher Hubble constant that would apply to our cosmic neighbourhood, but not to the universe as a whole."

Dr. Marra believes that this could partly explain the conflicting measurement results. The Hubble constant measured by the Planck satellite would represent a spatial average applicable to the entire universe. The Hubble constant determined through the movement of galaxies, however, would be valid only in the vicinity of the Milky Way. "Anyone expecting the measurements from our cosmic environs to match those of the microwave radiation implicitly assumes that we live in a typical region of the cosmos. But that isn't necessarily true," continues Prof. Amendola, whose working group has been studying the expansion of the universe for many years.

Using their research approach, the scientists have thus far been able to account for approximately one-fourth of the deviation between the two Hubble constants. Dr. Marra and his colleagues expect a detailed analysis will reduce the discrepancy even more. "Until now we have been working with a spherical Hubble Bubble. But it's far more likely that the bubble is asymmetrical, which would explain the deviating measurements even better," observes Dr. Ignacy Sawicki, also a researcher at the Institute for Theoretical Physics. "If the difference in data should manifest itself instead, this would be a major indicator that our former natural scientific view of the cosmos is still missing an ingredient," stresses Dr. Sawicki.

In addition to Valerio Marra and Ignacy Sawicki, Dr. Wessel Valkenburg from the Instituut-Lorentz of Leiden University was also member of Prof. Amendola's team. Their work was funded by the Collaborative Research Centre/Transregio "The Dark Universe."


Story Source:

The above story is based on materials provided by Heidelberg University. Note: Materials may be edited for content and length.


Journal Reference:

  1. Valerio Marra, Luca Amendola, Ignacy Sawicki, Wessel Valkenburg. Cosmic Variance and the Measurement of the Local Hubble Parameter. Physical Review Letters, 2013; 110 (24) DOI: 10.1103/PhysRevLett.110.241305

Cite This Page:

Heidelberg University. "Hubble bubble may explain different measurements of expansion rate of the universe." ScienceDaily. ScienceDaily, 9 September 2013. <www.sciencedaily.com/releases/2013/09/130909092520.htm>.
Heidelberg University. (2013, September 9). Hubble bubble may explain different measurements of expansion rate of the universe. ScienceDaily. Retrieved September 20, 2014 from www.sciencedaily.com/releases/2013/09/130909092520.htm
Heidelberg University. "Hubble bubble may explain different measurements of expansion rate of the universe." ScienceDaily. www.sciencedaily.com/releases/2013/09/130909092520.htm (accessed September 20, 2014).

Share This



More Space & Time News

Saturday, September 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

MIT BioSuit A New Take On Traditional Spacesuits

MIT BioSuit A New Take On Traditional Spacesuits

Newsy (Sep. 19, 2014) The MIT BioSuit could be an alternative to big, bulky traditional spacesuits, but the concept needs some work. Video provided by Newsy
Powered by NewsLook.com
Boeing, SpaceX to Send Astronauts to Space Station

Boeing, SpaceX to Send Astronauts to Space Station

AFP (Sep. 17, 2014) NASA selected Boeing and SpaceX on Tuesday to build America's next spacecraft to carry astronauts to the International Space Station (ISS) by 2017, opening the way to a new chapter in human spaceflight. Duration: 01:13 Video provided by AFP
Powered by NewsLook.com
East Coast Treated To Rare Meteor Sighting

East Coast Treated To Rare Meteor Sighting

Newsy (Sep. 16, 2014) Numerous residents along the East Coast reported seeing a bright meteor flash through the sky Sunday night. Video provided by Newsy
Powered by NewsLook.com
Space Race Pits Bezos Vs Musk

Space Race Pits Bezos Vs Musk

Reuters - Business Video Online (Sep. 16, 2014) Amazon CEO Jeff Bezos' startup will team up with Boeing and Lockheed to develop rocket engines as Elon Musk races to have his rockets certified. Fred Katayama reports. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins