How Can Gravitational Lensing Help Detect Dark Energy?

In summary, this paper addresses a potential means to measure dark energy over cosmological distances. It appears that the author has made a basic error in their assumptions, and other cosmologists are likely to provide a more in-depth critique of the paper in the near future.
  • #1
Chronos
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This paper; https://arxiv.org/abs/1701.03418, Direct Probe of Dark Energy through Gravitational Lensing Effect, addresses a potential means to measure dark energy over cosmological distances. Perhaps I am a bit slow, but, I found the basic idea sufficiently simple and obvious that I am surprised it hasn't been suggested before. Perhaps it was, and it merely eluded my attention. I feel flooded with questions I cannot yet even fully articulate. A couple which have surfaced include - 1] How might reverse lensing due to DE impact the apparent angular size of remote structures in the universe? 2] How might this affect the Friedmann equations?
 
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  • #2
Chronos said:
This paper; https://arxiv.org/abs/1701.03418, Direct Probe of Dark Energy through Gravitational Lensing Effect, addresses a potential means to measure dark energy over cosmological distances. Perhaps I am a bit slow, but, I found the basic idea sufficiently simple and obvious that I am surprised it hasn't been suggested before. Perhaps it was, and it merely eluded my attention. I feel flooded with questions I cannot yet even fully articulate. A couple which have surfaced include - 1] How might reverse lensing due to DE impact the apparent angular size of remote structures in the universe? 2] How might this affect the Friedmann equations?
I could be wrong, but at first blush it sounds to me like they're making a very basic error. The thing that ultimately curves light paths in the universe is the geometry of space-time. Since Dark Energy doesn't cluster (it can't to have the properties it has), its impact is going to be just the impact of curvature that appears in the Friedmann equations, where the only effect that looks like lensing stems from the spatial curvature parameter.

Maybe I'm wrong. I'm sure other cosmologists will weigh in on the paper within the next few weeks. But it really does not seem right to me.
 
  • #3
I agree they are not factoring out other contributors to the curvature. This paper is under the assumption of removal of matter/radiation fields.

I don't see any thing new here Everything on the would be true in a Lamba only toy universe. Unless I too am mistaken. So thanks for sharing Chronos

Though for scalar field modelling its got a good collection of relevant formulas P.

edit I have to double check but quintessence seems off as well. I need to dig out the correct textbooks I have on it. Yeah there is something off with what they have for quintessence. The tracker field w_q is time varying according to both wiki and Matt Roose. However to be completely honest I'm not really sure. So I dug up a review on it just in case anyone is interested.

https://arxiv.org/abs/1304.1961

Probably not important enough to go through a lot of effort lol
 
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  • #4
That dark energy is evenly distributed across the cosmos appears to explain why the lensing effect is only detectable across cosmological distances.
 

FAQ: How Can Gravitational Lensing Help Detect Dark Energy?

1. What is dark energy and how is it detected?

Dark energy is a theoretical form of energy that is thought to make up about 70% of the total energy in the universe. It is responsible for the acceleration of the expansion of the universe. Dark energy is detected through its effects on the movement of galaxies and the large-scale structure of the universe.

2. What methods are currently being used to detect dark energy?

Currently, there are three main methods being used to detect dark energy: Supernova surveys, baryon acoustic oscillations, and weak gravitational lensing. These methods involve observing the brightness and distribution of galaxies and measuring the effects of dark energy on their movement and structure.

3. How do scientists differentiate between dark energy and other forms of energy?

Dark energy is differentiated from other forms of energy through its unique properties and effects on the universe. It is thought to have a repulsive force, unlike other forms of energy, which have attractive forces. Additionally, dark energy is believed to be evenly distributed throughout the universe, while other forms of energy are not.

4. Why is detecting dark energy important?

Detecting dark energy is important because it can provide insight into the composition and fate of the universe. It can also help to explain the observed acceleration of the expansion of the universe and potentially lead to new theories and discoveries in the field of cosmology.

5. What challenges do scientists face in detecting dark energy?

One of the main challenges in detecting dark energy is its elusive nature. It cannot be directly observed and its effects are subtle, making it difficult to detect and measure. Additionally, the methods used to detect dark energy require large-scale surveys and precise measurements, which can be time-consuming and expensive.

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