EM Drive
A proposed spacecraft thruster that claimed to produce thrust without propellant, violating conservation of momentum, tested by NASA but ultimately attributed to measurement error.
OVERVIEW
The EM Drive (Electromagnetic Drive) was a proposed thruster design by British inventor Roger Shawyer in 2001 that claimed to produce thrust by bouncing microwaves in a closed cavity, requiring no propellant. This would violate the conservation of momentum, a fundamental law of physics. NASA's Eagleworks laboratory tested the EM Drive and reported anomalous thrust in 2014–2016, generating enormous media interest. However, subsequent testing by multiple laboratories (including a 2021 Dresden University study) concluded the thrust was an artifact of thermal expansion and electromagnetic interference. The EM Drive is now widely considered a dead end, though it remains a subject of interest in fringe physics communities.
KNOWN FACTS
NASA Eagleworks reported thrust in multiple test configurations
Chinese researchers reported similar anomalous thrust measurements
The thrust was measured in vacuum conditions, ruling out air convection
The effect was small but appeared consistent across different test setups
The drive generated significant interest from DARPA and NASA
CLAIMS
The EM Drive produces thrust without propellant, violating known physics
NASA's Eagleworks tests confirmed anomalous thrust
The drive could revolutionize space travel if the effect is real
The thrust may be explained by new physics (quantum vacuum, pilot wave theory)
The effect was suppressed by mainstream physics establishment
EVIDENCE FOR
NASA Eagleworks reported thrust in multiple test configurations
Chinese researchers reported similar anomalous thrust measurements
The thrust was measured in vacuum conditions, ruling out air convection
The effect was small but appeared consistent across different test setups
The drive generated significant interest from DARPA and NASA
EVIDENCE AGAINST
The 2021 Dresden University study conclusively showed the thrust was thermal expansion artifact
The measured thrust was at the threshold of measurement sensitivity
No theoretical mechanism for propellantless thrust exists in known physics
The NASA results were never published in a peer-reviewed journal
The EM Drive violates conservation of momentum, which has never been violated
OPEN QUESTIONS
No open questions recorded.
SOURCES
TIMELINE
Shawyer proposes the EM Drive concept
NASA Eagleworks reports anomalous thrust
NASA publishes results in peer-reviewed journal
Dresden study attributes thrust to thermal effects