how far do pulsar beams go lethal

Pulsar beams can be lethal only at very close range or if one were aimed directly at a nearby planet ; for Earth-like distances, they are not a practical threat because known pulsars are extremely far away and their beams are narrow.

What “lethal” means

A pulsar beam is a stream of intense radiation, often including radio, X-rays, and sometimes gamma rays, and that kind of exposure can be deadly because high-energy radiation can damage or strip atmospheres and kill surface life. The danger is less about a beam “going forever” and more about whether enough energy hits something nearby for long enough.

How far they go

Pulsar beams can travel across interstellar space; they are observed from hundreds or thousands of light-years away, and one reported particle beam associated with a pulsar was about 7 light-years long. That said, “how far” is not the same as “how harmful,” because the beam spreads, weakens, and usually misses most objects entirely.

Real-world risk

For Earth, the risk from known pulsars is considered very low because they are far away and their beams are narrow. A truly dangerous scenario would be an unusually nearby pulsar or a powerful high-energy beam pointed directly at a planet, which could be catastrophic.

Quick answer

So, in plain terms: pulsar beams can be lethal at astronomical close range, but not “across the galaxy” in any everyday sense. The beam can travel huge distances, yet lethal impact requires the right alignment, proximity, and energy.