Related Experiment Video
Updated: May 14, 2026
07:44
Longitudinal Intravital Imaging Through Clear Silicone Windows
Published on: January 5, 2022
Antilensing: the bright side of voids
Krzysztof Bolejko1, Chris Clarkson, Roy Maartens
1Sydney Institute for Astronomy, The University of Sydney, Sydney, New South Wales 2006, Australia.
Physical Review Letters
|February 7, 2013
Summary
Cosmic voids, typically thought to dim distant objects, actually brighten them due to a neglected relativistic Doppler effect. This finding impacts weak lensing and supernova observations.
Area of Science:
- Cosmology
- Astrophysics
- General Relativity
Background:
- Cosmic voids constitute over half the universe's volume.
- Weak lensing by voids is conventionally assumed to cause dimming.
- This dimming is attributed to reduced photon counts from smaller apparent object sizes.
Purpose of the Study:
- To investigate the lensing magnification effect of cosmic voids.
- To re-evaluate the standard weak lensing integral predictions.
- To explore relativistic effects on void lensing.
Main Methods:
- Analysis of the relativistic Doppler term in lensing.
- Comparison of linear relativistic theory with exact solutions.
- Estimation of nonlinear corrections to lensing convergence.
Main Results:
- A relativistic Doppler term, typically neglected, dominates void lensing at low redshifts.
- Contrary to expectations, voids cause magnification (brightening) of distant objects.
- Nonlinear corrections significantly enhance the relativistic effect, exceeding linear predictions by over 20% for deep voids.
Conclusions:
- The standard weak lensing model is insufficient for accurately describing void effects.
- Relativistic effects, including nonlinear corrections, are crucial for understanding void lensing.
- This phenomenon poses a significant systematic error for cosmological measurements like weak lensing density reconstruction and supernova surveys.
Related Concept Videos
02:28Leaky Scanning
During most eukaryotic translation processes, the small 40S ribosome subunit scans an mRNA from its 5' end until it encounters the first start AUG codon. The large 60S ribosomal subunit then joins the smaller one to initiate protein synthesis. The location of the translation initiation is largely determined by the nucleotides near the start codon as there may be multiple translation initiation sites present on the mRNA. Marilyn Kozak discovered that the sequence RCCAUGG (where R stands for...
01:10Detection of Black Holes
Although black holes were theoretically postulated in the 1920s, they remained outside the domain of observational astronomy until the 1970s.
Their closest cousins are neutron stars, which are composed almost entirely of neutrons packed against each other, making them extremely dense. A neutron star has the same mass as the Sun but its diameter is only a few kilometers. Therefore, the escape velocity from their surface is close to the speed of light.
Not until the 1960s, when the first neutron...
Their closest cousins are neutron stars, which are composed almost entirely of neutrons packed against each other, making them extremely dense. A neutron star has the same mass as the Sun but its diameter is only a few kilometers. Therefore, the escape velocity from their surface is close to the speed of light.
Not until the 1960s, when the first neutron...
01:21Boundary Conditions: Lossless Lines
Consider a single-phase, two-wire, lossless transmission line terminated by an impedance at the receiving end and a source with Thevenin voltage and impedance at the sending end. The line, with length, has a surge impedance and wave velocity determined by the line's inductance and capacitance.
At the receiving end, the boundary condition states that the voltage equals the product of the receiving-end impedance and current. This relationship is expressed as a function of the incident and...
At the receiving end, the boundary condition states that the voltage equals the product of the receiving-end impedance and current. This relationship is expressed as a function of the incident and...
01:16Focusing of Light in the Eye
Light rays enter the eye through the cornea, a transparent dome-shaped tissue that is the eye's outermost layer. The cornea bends or refracts, light rays traveling to the pupil. The shape of the cornea determines how much of the light is bent and whether the image will be focused correctly on the retina at the back of the eye. Once the light has passed through both refraction layers, it converges into a single focal point onto a small area. This is where photoreceptors start transforming...
01:11Blinding
Blinding is a commonly used method of not telling participants which treatment a subject is receiving. Blinding is a critical part of a randomized control trial or RCT. It reduces the bias that affects the results. In an RCT, blinding is used in the form of a placebo. A placebo effect occurs when untreated subjects falsely believe they have received the treatment and report improved symptoms. A placebo or a dummy treatment is administered to subjects to negate the bias caused by such an effect.
01:12Total Voids in Concrete
Total voids in concrete encompass gel water volume, capillary pores, and entrapped air. Gel water (retained within the cement hydration products) and physically entrapped or adsorbed water are significant for the hydration process. For complete hydration, it's estimated that the space needed for the products of a cubic centimeter of cement doubles. Capillary pores constitute the unoccupied space within the hydrated cement paste, with their size largely influenced by the water-to-cement ratio...