Lorentz Contraction: Gaining Mass & Shrinking

In summary, the Lorentz contraction occurs at all non-zero speeds and does not result in an object gaining mass. The concept of "relativistic mass" is no longer used by physicists. Length and mass are frame-dependent quantities, meaning they can be measured differently depending on the reference frame. This forum is a good resource for finding information on this topic.
  • #1
Swankie
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Hi all, modern physics student here. If the Lorentz contraction occurs at relativistic speeds, how does it gain mass yet get shorter?

The best I can think of is that it has to depend in which reference frame one is in at the time. Does anyone know any useful links where I can read about this?
 
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  • #2
You're right about the dependence on a reference frame. This forum is a good place to find information on this subject. Do a search for "mass" in the title and pick the threads that address your question. Click on this link to see the result of this search:

https://www.physicsforums.com/search.php?searchid=3078794
 
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  • #3
Swankie said:
If the Lorentz contraction occurs at relativistic speeds,

Length contraction occurs at ALL non-zero speeds.

Swankie said:
how does it gain mass

An object does NOT gain mass due to velocity. It gains "relativistic mass," but relativistic mass is a virtually useless quantity which physicists (for that reason) don't use anymore.

Swankie said:
yet get shorter?

Why does this seem paradoxical to you? Why do you think that the measured length of an object would have any effect on its mass?

Swankie said:
The best I can think of is that it has to depend in which reference frame one is in at the time.

Well yes, length and relativistic mass are certainly frame-dependent quantities. You could, for example, measure an object from a reference frame in which it is at rest. You could also measure the same object from a reference frame in which it has a velocity of 99.999% the speed of light. Obviously the two measurements will differ.
 
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1. What is Lorentz Contraction?

Lorentz Contraction is a principle in physics that describes the apparent shortening of an object in the direction of its motion as it approaches the speed of light. This phenomenon was first proposed by Dutch physicist Hendrik Lorentz in 1892.

2. How does Lorentz Contraction affect an object's mass?

According to Einstein's theory of relativity, as an object approaches the speed of light, its mass increases. This increase in mass is known as relativistic mass or Lorentz factor and is a result of the energy required to accelerate the object. Therefore, an object appears to gain mass as it approaches the speed of light.

3. What causes an object to shrink in Lorentz Contraction?

As an object moves at high speeds, it experiences a contraction in the direction of its motion. This is due to the time dilation effect, where time appears to slow down for the moving object, causing it to appear shorter in the direction of its motion.

4. Is Lorentz Contraction observable in everyday life?

No, Lorentz Contraction is only noticeable at extremely high speeds close to the speed of light. In everyday life, the effects of Lorentz Contraction are negligible and cannot be observed without advanced equipment.

5. How does Lorentz Contraction impact the concept of simultaneity?

Lorentz Contraction is closely related to the concept of simultaneity, which is the idea that two events that occur at the same time for one observer may occur at different times for another observer. As an object approaches the speed of light, its length contracts, and the concept of simultaneity becomes more complex. This is because the speed of light is constant for all observers, and time and space are relative to the observer's frame of reference.

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