What is mass in special relativity

What is mass in special relativity | Relativistic mass

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This video explores the fundamental role of mass in physical phenomena alongside space and time. It begins by explaining how mass influences gravity and inertia. Newton's law of universal gravitation states that every mass exerts a gravitational force on every other mass, proportional to their masses and inversely proportional to the square of their distance. Mass also relates to inertia, which resists changes in motion, requiring more force to alter the motion of objects with greater mass.
This video further discusses momentum, which depends on mass and velocity. For example, heavier or faster-moving cars need more force to change their speed. This principle extends to solar sails, which use sunlight's momentum to propel spacecraft, suggesting that light carries mass. This idea implies all forms of energy, when converted, possess mass, aligning with the concept that mass and energy are interchangeable.
Moving into special relativity, a thought experiment involving two trains illustrates how speed affects mass. Two twins on opposite trains at near-light speeds plan to punch each other. Due to time dilation, each perceives the other's punch as slower. However, when their fists collide, neither can overpower the other due to increased mass from relativistic speeds, illustrating that motion affects mass.
Finally, this video explains that mass is tied to energy, not just speed. A coiled spring inside a sealed box transferring energy to a spinning flywheel shows that potential energy contributes to mass. This demonstrates that added energy, not necessarily speed, increases mass, highlighting the intricate relationship between mass, energy, and motion.

Пікірлер: 11

@KaiVieira-jj7di 3 ай бұрын

Wrong, wrong, wrong. Mass is invariant, m^2=p^μp_μ, which is a Lorentz scalar. The increase in 3-momentum comes from time dilation.

@John-bq9jh 3 ай бұрын

What happens when we change their names. Bob becomes Jack and Jack becomes Bob. So whose clock ticks time slower? Bob or Jacks? Jacks or Bobs? Could both Jack and Bobs clock still tick at the same rate if Jack gives Bob 2 black eyes so he can’t observe Jack? What if they both gave each other black eyes so Jack couldn’t observe Bob and Bob couldn’t observe Jack? Maybe they can yell at each other instead. lol. What then? Once observations are at right angles of observations and motion something incredible happens. Keep in mind quantum effects. ie. length shrinks in direction of motion and hence angle of diffraction. But wait. Doesn’t that mean as Bob or Jack speeds up the angle of diffraction increases? Hm. Here’s one. Use a pendulum clock and calculate the time differential. Hm. The faster Bob moves the faster his time. Hm.

@Jaggerbush 3 ай бұрын

Snitch to @Dialect about it.

@geroellheimer 2 ай бұрын

6:20 why does a spinning object must have more mass? I mean an object in a straight trajectory relatively to the observer is one thing, but rotation undergoes a continuous process of changing the direction, like a continuous reset, while the wheel remains at the same location with the observer. why is it not sufficient to say, that at any given time, the spinning wheel contains momentum towards a given direction, and this momentum is continuously diverted to a different direction? I don't want to re-invent the definition of kinetic energy, but since a while I have the impression, that time is just another expression of energy and is always directed (while most people believe time exists in itself locally) maybe there is consistent math behind the wheel = more mass explanation, which can be proven through experiments(!), but intuitively this does not make sense to me.