This Week in the Universe: October 26th – November 1st

Astrophysics and Gravitation:

Hubble Tries to See into the Future

Illustration Credit: NASA, ESA, and G. Bacon (STScI), Science Credit: NASA, ESA, and J. Anderson and R. van der Marel (STScI)

From NASA, ESA, and J. Anderson and R. van der Marel (STScI):

The multicolor snapshot, at top, taken with Wide Field Camera 3 aboard NASA’s Hubble Space Telescope, captures the central region of the giant globular cluster Omega Centauri. All the stars in the image are moving in random directions, like a swarm of bees. Astronomers used Hubble’s exquisite resolving power to measure positions for stars in 2002 and 2006.

From these measurements, they can predict the stars’ future movement. The bottom illustration charts the future positions of the stars highlighted by the white box in the top image. Each streak represents the motion of the star over the next 600 years. The motion between dots corresponds to 30 years.

By precisely observing the stars in Omega Centauri, a 10 million star globular cluster within our galaxy, the NASA/ESA team has been able to predict the stars’ movements over the next 10,000 years.  Considering how many variables are in this system, this is an awfully impressive achievement.

For more, see Hubble Data Used to Look 10,000 Years into the Future.

High Energy Physics and Particles:

ANITA Balloon sees Cosmic Rays by Accident

Hoover, S., & et al. (2010). Observation of Ultrahigh-Energy Cosmic Rays with the ANITA Balloon-Borne Radio Interferometer Physical Review Letters, 105 (15) DOI: 10.1103/PhysRevLett.105.151101

Credit: Physical Review Letters » Covers » Vol. 105, Iss. 15- Locations of direct (black) and reflected (red) detection of ultrahigh energy cosmic ray events by the ANITA balloon experiment over Antarctica. The field of view is delineated by the dashed blue line.

From the abstract:

We report the observation of 16 cosmic ray events with a mean energy of 1.5×1019 eV via radio pulses originating from the interaction of the cosmic ray air shower with the Antarctic geomagnetic field, a process known as geosynchrotron emission. We present measurements in the 300–900 MHz range, which are the first self-triggered, first ultrawide band, first far-field, and the highest energy sample of cosmic ray events collected with the radio technique. Their properties are inconsistent with current ground-based geosynchrotron models.

The ANITA Experiment, while on the hunt for cosmic neutrinos, ended up seeing 16 exceptionally high energy cosmic ray events (particles with energy several orders of magnitude greater than those made in the LHC).  Accidental observations are always fun, especially when they suggest a new technique for observing known phenomena.  Perhaps radio interferometer equipped balloons will now be used to detect these rare cosmic ray events.

For more, see Antarctic balloon sees particles with a million times more energy than the Large Hadron Collider.

Confirmed Top Quark Observation in the LHC

CMS Collaboration (2010). First Measurement of the Cross Section for Top-Quark Pair Production in Proton-Proton Collisions at sqrt(s)=7 TeV arXiv arXiv: 1010.5994v1

Exciting news! The CMS Collaboration has published their first confirmed observations of top quark production at the LHC this week.  This is especially exciting because it means that we’ll be able to study top quarks in multi-TeV proton-proton collisions for the first time.  At the Tevatron, top quark pairs are mainly produced via quark-antiquark annihilation, while at the LHC top quark pair production is expected to be dominated by a gluon fusion process.  Thus, observing top quark production is crucial to our understanding of this new mechanism. This is an important step in the early physics program at the LHC, since, “many signatures of new physics models accessible at the LHC either suffer from top-quark production as a significant background or contain top quarks themselves.”

The US at the Large Hadron Collider Photo of the Week

Credit: US/LHC - Candidate W-boson decay to tau and neutrino in ATLAS

The US/LHC has started an Event of the Week flickr account, showcasing an exciting and beautiful particle event from the current LHC runs every week.  This weeks was a candidate W-boson decaying into a tau and a neutrino within the ATLAS detector!

General Relativity, Quantum Gravity, et al.:

Want to Learn More about Gauge Gravity?

Andrew Randono (2010). Gauge Gravity: a forward-looking introduction arXiv arXiv: 1010.5822v1

Andrew Randono has a lengthy, but kind, introduction to the exciting world of gauge gravity.  If you’ve always wanted to know what gravity has to do with (A)dS-gauge theories, then this is worthwhile read.

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One Response to This Week in the Universe: October 26th – November 1st

  1. Rob says:

    Your old posts about the thermodynamics of gravity (aka, Verlinde and Padmanabhan) are now somewhere else, so I will post this question here. I would like to ask you what do think of this brave attempt to link Gravity and QFT through Rindler observers?

    Physics from information
    Jae-Weon Lee
    http://arxiv.org/abs/1011.1657

    This is an ongoing review on my conjecture that information processing at causal horizons is the key ingredient of all physics. Assuming that information is fundamental and the information propagates with finite velocity, one can find that main physical laws such as Newton’s second law and Einstein equation simply describe the energy-information relation (dE=TdS) for matter or space time crossing a causal horizon with temperature T for observers. Quantum mechanics arises from ignorance of the observers about matter crossing the horizon, which explains why superluminal communication is impossible even with quantum entanglement. This approach also explains the origin of Jacobson’s thermodynamic formalism of Einstein gravity and Verlinde’s entropic gravity. When applied to a cosmic causal horizon, the conjecture reproduces the observed dark energy and demands the zero cosmological constant.