超强激光或可撕裂真空：基于量子电动力学（QED）的技术探讨

Great question! Let’s unpack this using the quantum electrodynamics (QED) framework you referenced.

First, a quick recap of the QED vacuum: it’s not the empty void classical physics describes. Thanks to quantum uncertainty, virtual electron-positron pairs constantly pop into existence for tiny fractions of a second, then immediately annihilate each other. These are "virtual" because they don’t stick around long enough to be directly observed under normal conditions.

Now, to your core question: Yes, in theory, a sufficiently intense laser could "tear" the vacuum—but the required intensity is far beyond anything we can currently build. Here’s why:

• A laser’s strong electric field can interact with these virtual particle pairs. Normally, the pairs vanish too quickly for the field to have a meaningful effect. But when the field reaches the Schwinger limit (roughly $10^{18}\ \text{V/m}$), the energy density becomes high enough to separate the virtual electron and positron before they annihilate.
• Once separated, these particles stop being "virtual" and become real, detectable particles. This process—turning vacuum energy into observable matter—is what we’d call "tearing the vacuum," and it’s a direct prediction of QED (dubbed the Schwinger effect).

For context, the most powerful lasers we’ve built to date only reach around $10^{14}\ \text{V/m}$—that’s four orders of magnitude below the Schwinger limit. So while we can’t pull this off in the lab right now, the theoretical foundation is solid within QED.

内容的提问来源于stack exchange，提问作者Keith McClary