What Happens to Mass as it Approaches the Speed of Light?

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Discussion Overview

The discussion revolves around the concept of mass as an object approaches the speed of light, exploring whether mass increases, remains constant, or becomes zero at light speed. It touches on theoretical implications and misunderstandings related to mass in the context of special relativity.

Discussion Character

  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant believes that as an object accelerates, its mass increases and would become infinite at the speed of light, while others argue that this is a misconception.
  • Another participant clarifies that "mass" typically refers to rest mass, which does not change, and asserts that an object with mass cannot reach the speed of light, making the original question nonsensical.
  • Some participants suggest that both the original poster and their friends are mistaken regarding the nature of mass and its behavior at relativistic speeds.
  • A different perspective is introduced, where the observer's motion does not affect the mass of an object, reinforcing the idea that mass remains unchanged regardless of the observer's frame of reference.
  • Questions arise regarding the relationship between energy and mass, with some participants indicating that this topic is off-topic for the original question.

Areas of Agreement / Disagreement

Participants express differing views on the nature of mass at relativistic speeds, with no consensus reached on the original poster's understanding versus their friends' claims. The discussion remains unresolved regarding the implications of mass as speed approaches that of light.

Contextual Notes

There are limitations in the discussion regarding the definitions of mass, the assumptions about relativistic effects, and the implications of energy-mass equivalence that remain unresolved.

teetar
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Pretty straight-forward, I'm just curious. My current level and understanding of physics has lead me to believe that as an object accelerates it's mass becomes higher and if it were to be able to reach the speed of light it would get infinite mass. I believe this currently, however, two of my friends have denied this statement saying that, rather, an object's mass will become zero when it reaches the speed of light. I'm just wondering if I'm correct or if they are. If they're correct, is it just a simple misunderstanding, or mistake on my part, or is it that I don't understand physics to the correct level to attempt to understand this yet?

Thanks for anyone who can respond to this, and please have a nice day!
 
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It is a very common misconception that an object's mass changes at its speed increases. The term "mass" refers to "rest mass", which is the mass the object has in its own inertial frame. This never changes. That, along with the fact that an object with mass cannot reach the speed of light, means that your question is a nonsensical one. Any object with mass cannot reach the speed of light so we cannot say what will happen "if" it did.
 
teetar said:
Pretty straight-forward, I'm just curious. My current level and understanding of physics has lead me to believe that as an object accelerates it's mass becomes higher and if it were to be able to reach the speed of light it would get infinite mass. I believe this currently, however, two of my friends have denied this statement saying that, rather, an object's mass will become zero when it reaches the speed of light. I'm just wondering if I'm correct or if they are. If they're correct, is it just a simple misunderstanding, or mistake on my part, or is it that I don't understand physics to the correct level to attempt to understand this yet?

Thanks for anyone who can respond to this, and please have a nice day!

In addition to what Drakkith has stated:

1. The "mass" that you know is what we term as the rest or invariant mass. This mass doesn't change. So both you and your friends are mistaken. Do I get to win the bet, if any?

2. If you are invoking this thing called "relativistic mass" then read this first

https://www.physicsforums.com/showthread.php?t=642188#post4106101

Zz.
 
Thanks guys! I'm sorry I posted this here, I should've looked into it more to find an answer, I obviously need to learn more :P
 
Here's an answer from another perspective. Suppose that instead of you being "stationary" and the object zooming past you at a speed approaching warp 1, it is the object that is "stationary," and it is you who are zooming past the object at a speed approaching warp 1 (in the opposite direction). I think you will agree that your motion as a passive observer cannot affect the mass of the object in any way (after all, you are not even coming close to contacting it). Yet from your perspective, it is the object that is zooming past you. So, either way, its mass can't change.
 
Drakkith said:
Any object with mass cannot reach the speed of light so we cannot say what will happen "if" it did.

Please explain. Light as a wave carries energy, and energy is equivalent to mass, right?
 
vanceEE said:
Please explain. Light as a wave carries energy, and energy is equivalent to mass, right?

No it is not. Read the Relativity FAQ!

That question is also off topic to what the OP is asking. Either ask this elsewhere, or better yet, read the numerous other threads and our FAQ that have addressed this.

Zz.
 
ZapperZ said:
Read the Relativity FAQ!

Please send link. Thank you
 
vanceEE said:
Please send link. Thank you

ko5t.jpg


Zz.
 
  • #10
teetar said:
Thanks guys! I'm sorry I posted this here, I should've looked into it more to find an answer, I obviously need to learn more :P

Nonsense, it's a perfectly valid question to ask. Why else would this forum exist if not to help people?
 

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