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Summoned objects aren’t near light speeddon’t travel that fast.

Objects summoned by Accio don’t move anywhere near light speed, despite JKR’s statement. They visibly move towards whoever Summoned them. Objects traveling at light speed wouldn’t be visible to the human eye, so therefore, objects summoned by Accio cannot be moving near light speed.

“Mrs Weasley pointed her wand at George’s pocket and said, ‘Accio!’‘Accio!’

Several small, brightly coloured objects zoomed out of George’s pocket; he made a grab for them but missed, and they sped right into Mrs Weasley’s outstretched hand.”
- Harry Potter and the Goblet of Fire, Chapter 6 (The Portkey)

They also don’t arrive instantly, which they would if they truly traveled at anything close to light speed. When Harry Summons his Firebolt, it gets to him quickly, but still takes enough time to arrive for him to wonder if he successfully Summoned it.

“Accio Firebolt!’ he shouted.

He waited, every fibre of him hoping, praying … if it hadn’t worked … if it wasn’t coming … he seemed to be looking at everything around him through some sort of shimmering, transparent barrier, like a heat haze, which made the enclosure and the hundreds of faces around him swim strangely …

And then he heard it, speeding through the air behind him; he turned and saw his Firebolt hurtling towards him around the edge of the woods, soaring into the enclosure, and stopping dead in mid-air beside him, waiting for him to mount.”
- Harry Potter and the Goblet of Fire, Chapter 20 (The First Task)

Therefore, objects summoned by Accio don’t truly move anywhere near light speed, so it’s a relatively safe spell to use.

Summoned objects aren’t near light speed.

Objects summoned by Accio don’t move anywhere near light speed, despite JKR’s statement. They visibly move towards whoever Summoned them. Objects traveling at light speed wouldn’t be visible to the human eye, so therefore, objects summoned by Accio cannot be moving near light speed.

“Mrs Weasley pointed her wand at George’s pocket and said, ‘Accio!’

Several small, brightly coloured objects zoomed out of George’s pocket; he made a grab for them but missed, and they sped right into Mrs Weasley’s outstretched hand.”
- Harry Potter and the Goblet of Fire, Chapter 6 (The Portkey)

They also don’t arrive instantly, which they would if they truly traveled at anything close to light speed. When Harry Summons his Firebolt, it gets to him quickly, but still takes enough time to arrive for him to wonder if he successfully Summoned it.

“Accio Firebolt!’ he shouted.

He waited, every fibre of him hoping, praying … if it hadn’t worked … if it wasn’t coming … he seemed to be looking at everything around him through some sort of shimmering, transparent barrier, like a heat haze, which made the enclosure and the hundreds of faces around him swim strangely …

And then he heard it, speeding through the air behind him; he turned and saw his Firebolt hurtling towards him around the edge of the woods, soaring into the enclosure, and stopping dead in mid-air beside him, waiting for him to mount.”
- Harry Potter and the Goblet of Fire, Chapter 20 (The First Task)

Therefore, objects summoned by Accio don’t truly move anywhere near light speed, so it’s a relatively safe spell to use.

Summoned objects don’t travel that fast.

Objects summoned by Accio don’t move anywhere near light speed, despite JKR’s statement. They visibly move towards whoever Summoned them. Objects traveling at light speed wouldn’t be visible to the human eye, so therefore, objects summoned by Accio cannot be moving near light speed.

“Mrs Weasley pointed her wand at George’s pocket and said, ‘Accio!’

Several small, brightly coloured objects zoomed out of George’s pocket; he made a grab for them but missed, and they sped right into Mrs Weasley’s outstretched hand.”
- Harry Potter and the Goblet of Fire, Chapter 6 (The Portkey)

They also don’t arrive instantly, which they would if they truly traveled at anything close to light speed. When Harry Summons his Firebolt, it gets to him quickly, but still takes enough time to arrive for him to wonder if he successfully Summoned it.

“Accio Firebolt!’ he shouted.

He waited, every fibre of him hoping, praying … if it hadn’t worked … if it wasn’t coming … he seemed to be looking at everything around him through some sort of shimmering, transparent barrier, like a heat haze, which made the enclosure and the hundreds of faces around him swim strangely …

And then he heard it, speeding through the air behind him; he turned and saw his Firebolt hurtling towards him around the edge of the woods, soaring into the enclosure, and stopping dead in mid-air beside him, waiting for him to mount.”
- Harry Potter and the Goblet of Fire, Chapter 20 (The First Task)

Therefore, objects summoned by Accio don’t truly move anywhere near light speed, so it’s a relatively safe spell to use.

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Summoned objects aren’t near light speed.

Objects summoned by Accio don’t move anywhere near light speed, despite JKR’s statement. They visibly move towards whoever Summoned them. Objects traveling at light speed wouldn’t be visible to the human eye, so therefore, objects summoned by Accio cannot be moving near light speed.

“Mrs Weasley pointed her wand at George’s pocket and said, ‘Accio!’

Several small, brightly coloured objects zoomed out of George’s pocket; he made a grab for them but missed, and they sped right into Mrs Weasley’s outstretched hand.”
- Harry Potter and the Goblet of Fire, Chapter 6 (The Portkey)

They also don’t arrive instantly, which they would if they truly traveled at anything close to light speed. When Harry Summons his Firebolt, it gets to him quickly, but still takes enough time to arrive for him to wonder if he successfully Summoned it.

“Accio Firebolt!’ he shouted.

He waited, every fibre of him hoping, praying … if it hadn’t worked … if it wasn’t coming … he seemed to be looking at everything around him through some sort of shimmering, transparent barrier, like a heat haze, which made the enclosure and the hundreds of faces around him swim strangely …

And then he heard it, speeding through the air behind him; he turned and saw his Firebolt hurtling towards him around the edge of the woods, soaring into the enclosure, and stopping dead in mid-air beside him, waiting for him to mount.”
- Harry Potter and the Goblet of Fire, Chapter 20 (The First Task)

Therefore, objects summoned by Accio don’t truly move anywhere near light speed, so it’s a relatively safe spell to use.