# CMB Anisotropy: Measuring Our Motion Through Space

• bwana
In summary, Smoot et. al. have measured a dipole and higher order anisotropies in the cosmic microwave background, which has been interpreted as our motion through the universe. However, to determine if the dipole is due to our motion or anisotropic expansion of space, measurements would need to be taken from two distant locations. This raises the question of whether we are moving through space or stationary in an expanding universe. Both scenarios could potentially explain the observed dipole.
bwana
Smoot et. al. have measure a dipole (as well as higher order anisotropies) in the cosmic microwave background. This has been interpreted as our motion through the universe.

so how do we know that the dipole is due to our motion through space and not the anisotropic expansion of space? the only way to know this would be to make measurements from two places that are far apart (one measurement taken within our galaxy and another from outside).

So either we're moving through space in 1 direction, or we're stationary and space is expanding faster on one side of us than the other... ?

It sounds to me like the same thing, just two different frames of reference.

right, either we are moving through a spherically expanding space or we are motionless in an expanding weiner. if we were moving through space, shouldn't there be a blueshift in the direction opposite to the redshift behind us?

## 1. What is CMB Anisotropy?

In simple terms, CMB Anisotropy refers to the small variations or fluctuations in the temperature of the cosmic microwave background (CMB) radiation. This radiation is the leftover heat from the Big Bang and is present everywhere in the universe. These fluctuations in temperature can help us understand the structure and evolution of the universe.

## 2. How is CMB Anisotropy measured?

CMB Anisotropy is measured using specialized instruments called telescopes that are designed to detect microwave radiation. These telescopes scan different parts of the sky and measure the temperature fluctuations in the CMB. The data collected from these measurements is then analyzed to create a map of the CMB temperature variations.

## 3. What causes CMB Anisotropy?

The most widely accepted explanation for CMB Anisotropy is the inflationary model of the universe. According to this model, the universe underwent a rapid expansion in its early stages, leaving behind tiny ripples in the fabric of space-time. These ripples eventually grew into the large-scale structures we see in the universe today, including the temperature variations in the CMB.

## 4. What can CMB Anisotropy tell us about our motion through space?

CMB Anisotropy can provide valuable information about our motion through space by measuring the dipole anisotropy in the CMB. This refers to the slight difference in temperature in opposite directions of the sky, which is caused by our motion through the universe. By analyzing this data, scientists can calculate our velocity and direction of motion relative to the rest of the universe.

## 5. What are the implications of studying CMB Anisotropy?

Studying CMB Anisotropy can help us better understand the origins, evolution, and structure of the universe. It can also provide insights into the fundamental laws of physics and the nature of dark matter and dark energy. Additionally, studying CMB Anisotropy can help us confirm or refine existing cosmological models and theories, leading to a deeper understanding of our place in the universe.

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