My sister plays her PS4 all day and whenever her remote vibrates while it's sitting on the couch, I can feel the vibration from a different seat.

I don't understand how the vibration of a little remote can move throughout a whole, large couch.

The phenomenon you're experiencing is called "resonance". Resonance occurs when an object vibrates at its natural frequency or a multiple of it, causing nearby objects to respond in a similar manner. In this case, when the remote vibrates, it creates waves of energy that travel through the couch, and if the couch's natural frequency matches the frequency of the vibration, resonance occurs.

To understand why the vibration of a small remote can move throughout an entire couch, we need to consider a few factors:

1. Material composition: The material of the couch plays a significant role in transmitting vibrations. If the couch is made of a rigid material like wood, vibrations might not travel as easily compared to a couch made of a more flexible material like foam or springs.

2. Contact points: When the remote is placed on the couch, its vibrations are directly transmitted to the surface it rests on. If the remote is in constant contact with the couch, the energy from the vibration can transfer to the surrounding material.

3. Resonance frequency: Every object has a natural frequency at which it tends to vibrate more easily. If the frequency of the remote's vibration matches or is close to the couch's resonant frequency, the energy transfer becomes more efficient, resulting in the vibrations being felt in other parts of the couch.

4. Amplification: Depending on the construction and design of the couch, it is possible that certain parts of the couch, such as springs or cushions, act as amplifiers, further propagating the vibrations throughout the seat.

It's also worth noting that the perception of vibrations can vary depending on your sensitivity, the specific couch design, and where you are seated relative to the remote. Some people may be more attuned to feeling vibrations, while others may not notice them as easily.

Overall, the combination of the remote's vibrating energy, the material composition of the couch, resonance frequencies, and potential amplification factors contribute to the vibrations being felt throughout the large couch, even though they originate from a small remote.