What Physics Teachers Get Wrong About Tides! | Space Time | PBS Digital Studios

Recent questions

• Why do lakes not experience tides?

  Lakes lack tides due to insufficient area for pressure build-up, unlike oceans. Tides are caused by cumulative sideways traction, not lifting or stretching of the oceans. The absence of significant pressure build-up in lakes prevents the formation of tides, as the forces required for tides to occur are not present in bodies of water with limited surface area like lakes. While mini tides can occasionally occur in large lakes, they are often overshadowed by other factors and do not exhibit the same magnitude or regularity as ocean tides.

• How are tides different from gravitational forces?

  Tides are not caused by the oceans being stretched by gravitational differentials, as commonly believed. Instead, tidal forces act like anti-gravity along the Earth/Moon line due to Earth's non-inertial frame. While gravity affects all objects identically, tides are a result of the complex interactions between gravitational forces, the Earth's rotation, and the Moon's position. Unlike the uniform gravitational pull experienced by objects, tides involve unique forces that create variations in water levels along coastlines.

• What causes tides in oceans?

  Tides in oceans are caused by cumulative sideways traction, not lifting or stretching of the oceans. The traditional explanation of tides involving the Moon's gravity differential is flawed, as tides are not a result of the oceans being physically pulled by the Moon. Instead, the gravitational forces between the Earth, Moon, and Sun create a complex system of tidal forces that lead to the rise and fall of water levels in oceans. These forces act in a sideways manner, generating the characteristic ebb and flow of tides.

• Do tides have a consistent pattern globally?

  Tides are more akin to pimples than taffy, with complex variations based on location and geography. While tides exhibit a general pattern of rising and falling water levels, the specific characteristics of tides can vary significantly depending on the geographical location. Factors such as coastline shape, underwater topography, and proximity to the Moon and Sun influence the amplitude and timing of tides in different regions. This variability results in a diverse range of tidal patterns across the globe.

• Can classical theories be quantized in macroscopic regimes?

  Quantizing classical theories is feasible in macroscopic regimes, yielding close agreement with general relativity. While challenges arise at very small scales due to unresolved infinities in the quantum version of gravity, the process of quantizing classical theories has shown promise in macroscopic contexts. By applying quantum principles to classical theories like general relativity, researchers have been able to achieve close agreement with established models. However, the transition to very small scales presents difficulties due to unresolved issues related to infinities in the quantum description of gravity.