Then the researchers came up with the idea of a light barrier.

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Some scientists have long thought there might be a way to surpass the light barrier, and if so, certain limited kinds of time travel might be possible.

FORBES: Light's Limit: There's No Getting Around It

The bill has proposed a definition of a high hedge at two metres, formed by a row or two of evergreens, such as the fast-growing leylandii, which forms a barrier to light.

BBC: High hedge bill is intended to reduce disputes

But in the 1990s Gilder became convinced that the speed of light would be the final unpassable barrier governing the pace of all digital technology.

FORBES: Digital Rules

Why hadn't the Texas Democratic Party broken this barrier years ago and elected a Latino Democrat to the Senate, especially in light of the decades of support it has enjoyed from Latino voters?

CNN: As two politicians ascend, new sway for Latinos?

The barrier to using the devices in vehicles is no one knows how to carry enough hydrogen, a light and flammable gas that is difficult to compress, to be useful.

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