**Compute moving from electrical signals to light:** This refers to the transition from using electrical signals for data processing and transmission in computers to using light, or photons. This shift is driven by the need for higher speeds and more efficient data transmission. **Photons travel faster than electrons and can carry more information with less energy loss and interference.** Technologies like optical fibers and photonic integrated circuits are examples of this transition, where light is used for **communication and computing tasks.** **Interconnect barriers - sending data between chips limits us:** As microprocessors become faster and more powerful, the ability to move data quickly and efficiently between different parts of a computer system becomes a critical bottleneck. The interconnects, or pathways, that transfer data between chips can't keep up with the processing speed, leading to delays and reduced performance. This is a significant challenge in computer architecture, as improving interconnect technology is essential for the continued scaling of computer performance. **Heat Death of Chips, Dennard's Law:** Dennard's Law states that as transistors get smaller, their power density stays constant, so the power usage remains in proportion with the area. However, as we've continued to shrink transistors, this scaling has broken down, leading to increased power density. This results in excessive heat, termed "heat death," which can reduce reliability and performance of chips. Managing this heat has become a critical aspect of modern chip design. **Today, computer chips have the same energy density as a nuclear reactor:** Modern computer chips generate a significant amount of heat due to their high performance and energy density. The energy density (the amount of energy stored or used in a given system per unit volume) of some chips can be comparable to that of a nuclear reactor core. This comparison highlights the challenges in dissipating heat and maintaining the operational integrity of the chips. **Silicon thermal resistivity is non-linear with temperature:** As the temperature of silicon, the primary material in most computer chips, increases, its ability to conduct heat changes non-linearly. This means that as chips get hotter, their ability to dissipate heat efficiently decreases, compounding the thermal management challenge. Understanding and managing this relationship is crucial for chip design, especially as processors continue to become faster and more densely packed with transistors. **Water Cooling is standard for computer chips today, water run over the chip:** Water cooling is a common method for managing heat in high-performance computing systems. It involves circulating water or another coolant over or near the surface of the chip to absorb and carry away heat. This method is more efficient than air cooling and is used in everything from personal computers to large data centers to prevent overheating and maintain performance. **Immersion Cooling - chips put in a liquid that boils, when it does the heat capacity increases:** Immersion cooling is an advanced cooling technique where the entire chip or system is submerged in a thermally conductive, but electrically insulating, liquid. As the chip heats up, the liquid absorbs the heat and begins to boil. The phase change from liquid to gas significantly increases the heat capacity, allowing for efficient heat removal. This method is particularly useful for very high-density setups like data centers. **For chips to work in space, you need to radiate the heat, shine the heat/photons away:** In the vacuum of space, traditional cooling methods like air convection are ineffective since there's no air to carry away heat. Space-bound systems must rely on radiation to dissipate heat. This involves emitting the heat as infrared radiation, a process that requires carefully designed surfaces that can radiate heat efficiently into the coldness of space. Managing thermal conditions is critical for the reliability and performance of space technology.