The following is an unedited transcript from a technical deep-dive session between "Alex," an aspiring competitive gamer and networking enthusiast, and "Dr. K," a veteran network infrastructure architect specializing in trans-oceanic cable deployments.
Alex: I’ve been trying to figure out a specific issue that’s been driving me crazy. I live in Seoul, and I frequently play on servers in Los Angeles. I have a 1 Gigabit optical fiber connection running straight into my apartment. My router is enterprise-grade, and my PC is state-of-the-art. Yet, my ping flatlines around 130 to 140 milliseconds. It never goes lower. With all this modern technology, why can't we just get 10ms ping globally?
Dr. K: It's a fantastic question, Alex, and it’s one that brings us face-to-face with the absolute limits of our universe. The short answer? Albert Einstein. The long answer involves refractive indices, the curvature of the Earth, and millions of dollars of underwater infrastructure.
Let's break down the journey of your exact signal. When you press a key in Seoul to perform an action on a server in Los Angeles, the data doesn't just magically teleport. It travels as pulses of light through a physical cable.
Alex: So, light is fast. The speed of light is roughly 300,000 kilometers per second, right? The distance between Seoul and LA is about 9,600 kilometers. At the speed of light, that trip should take about 32 milliseconds. So a round trip—my computer sending the signal and receiving the response—should logically be 64 milliseconds. Why am I seeing 140ms?
Dr. K: Your math is perfect for light traveling through a vacuum. But your data isn't traveling through empty space. It's traveling through glass—specifically, silica glass fibers. And that changes the equation entirely.
In a vacuum, light travels at exactly 299,792 kilometers per second ($c$). But when light enters a medium like glass, it slows down. This property is defined by the Refractive Index ($n$). The speed of light in a medium ($v$) is calculated as $v = c / n$.
The core of a standard single-mode optical fiber used in submarine telecommunications has a refractive index of about 1.46.
Alex: Let me do the math. So 300,000 divided by 1.46... that’s roughly 205,000 kilometers per second?
Dr. K: Precisely. Inside the fiberoptic cable at the bottom of the Pacific Ocean, light is traveling at roughly 200,000 kilometers per second, which translates to about 5 microseconds per kilometer ($5 \mu s/km$).
Now, let's look at the physical geography. A submarine cable doesn't go in a perfectly straight line through the Earth's crust. It is laid across the uneven topology of the ocean floor, navigating around trenches, avoiding tectonic fault lines, and linking up to specific landing stations. The actual cable distance between a landing station in South Korea (like Geoje or Taean) and the US West Coast (like Oregon or California) is often around 10,500 to 11,000 kilometers depending on the specific cable system.
Alex: Okay, so applying the 5 microseconds per kilometer rule to an 11,000-kilometer cable... that’s 55 milliseconds for a one-way trip. Round trip is 110 milliseconds. We're getting closer to my 130ms ping! Where does the remaining 20ms come from?
Dr. K: That’s where active network infrastructure and the "last mile" routing add up. Your signal doesn't just bounce back cleanly from the edge of the US coast.
First, let's talk about the underwater journey. A signal of light naturally attenuates (loses strength) over distance due to scattering and absorption within the glass. To ensure the signal survives an 11,000-kilometer trip, submarine cables have optical amplifiers—specifically Erbium-Doped Fiber Amplifiers (EDFAs)—spliced into the cable every 50 to 100 kilometers. While these amplifiers are purely optical and add very little delay, the cumulative effect of hundreds of them, plus the dispersion compensation modules, adds a fraction of a millisecond.
However, the major delay occurs on dry land. Once the light pulse hits the landing station in California, it must be converted from an optical signal into an electrical signal (O-E-O conversion) if it needs to be routed through standard routers, though much of modern long-haul transit keeps it optical.
Your signal is handed off from the trans-Pacific carrier to a domestic ISP. It passes through multiple routers in data centers. Each router has to look at the packet header, determine the next hop, and forward it. This routing and switching processing adds microseconds per device, but large queues or non-direct peering arrangements can force your packet to take a sub-optimal path zig-zagging across the state before it actually reaches the game server in Los Angeles.
Alex: And then the same thing happens in reverse when the server sends the packet back to me. Plus, my own local ISP in Korea has its own routing overhead between my apartment and the submarine landing station.
Dr. K: Exactly. The 130ms to 140ms you are experiencing is actually an engineering marvel. You are essentially brushing up against the physical limits of the universe.
The baseline theoretical minimum—the absolute "speed limit" over the physical ocean floor—is around 110ms. The remaining 20ms to 30ms is entirely consumed by the literal routing logic of the domestic ISPs on both ends and the game server processing time.
Alex: That's fascinating, but also slightly depressing for competitive gaming. Does this mean no technological advancement can ever bring my ping from Seoul to LA down to 10ms?
Dr. K: Unless we discover a way to tunnel signals through other dimensions or bypass the refractive index of glass entirely, conventional fiber optics won't get you there.
There is one alternative technology trying to bypass the "glass penalty." Hollow-core optical fibers are currently in development and early deployment. Instead of a solid silica core, the light travels through a hollow center filled with air or specific gases. Since the refractive index of air is incredibly close to 1.0 (virtually a vacuum), light travels through a hollow-core fiber at nearly $c$, or roughly 300,000 km/s.
If we could lay an 11,000-kilometer hollow-core cable across the Pacific, the raw latency one-way would drop from 55ms down to about 36ms. The round trip physical floor would drop from 110ms to 72ms. With optimal routing, you might see pings in the 80ms to 90ms range.
Alex: Wow. 80ms would be a massive improvement. What about satellite internet, like Starlink? They operate in the vacuum of space, don't they?
Dr. K: They do! Low Earth Orbit (LEO) satellites transit data through the vacuum of space using lasers for inter-satellite links. Because light travels at $c$ in space, the transit time between satellites is 30% faster than in undersea cables.
However, you must account for the vertical trip—up to the satellite (500km) and back down. But over massive intercontinental distances, if the signal bounces through a pure laser mesh in space from a ground station in Korea to a ground station in California, the theoretical latency can indeed beat fiber optics. High-frequency traders have been heavily investing in microwave and LEO satellite communications purely to shave off 5 to 10 milliseconds between financial capitals like New York and London or Chicago and Tokyo.
Alex: So, for now, when I look at that 130ms ping... I shouldn't be angry at my ISP.
Dr. K: No. You should look at that 130ms and realize that your keystroke just traversed an ocean, triggered a logic gate on another continent, and returned to your monitor—all within the blink of an eye, governed strictly by the immutable laws of physics.
Alex: That completely changes my perspective. Thanks, Dr. K. I’ll stop rebooting my router now.